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I am a clone. That is, I am a colony of cells that developed from a single fertilized egg cell. Most animals are clones like me. It is a slight oversimplification to say that all of an animal's cells are genetically identical to each other. Some cells have mutations. In mammals, some cells (red blood cells) lack a nucl... | 15024412 | PMC368156 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e43 |
Introduction
Spontaneous mutations in mice and rats have provided important information about mammalian iron homeostasis (reviewed in Andrews 2000). Interestingly, three independent, autosomal recessive mutants have been shown to have the same amino acid substitution in a key iron transport molecule. Two strains of mut... | 15024413 | PMC368157 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e50 |
Introduction
Gene duplication is the most important source of new genes and consequently a vital source of genetic novelty (Ohno 1970). Recently, the availability of completely sequenced genomes has sparked renewed attention in this subject at the genome scale. Most genomic studies of gene duplication have focused on t... | 15024414 | PMC368158 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e55 |
Introduction
Despite intense research efforts, no consensus has been reached about the genetic relationship between early modern humans and archaic human forms such as the Neandertals. While supporters of “multiregional evolution” argue for genetic exchange or even continuity between archaic and modern humans (Weidenre... | 15024415 | PMC368159 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e57 |
The ability to taste food is a life-and-death matter. Failure to recognise food with a high enough caloric content could mean a slow death from malnutrition. Failure to detect a poison could result in near-instant expiration. And now, as researchers begin to understand some of the nuts and bolts of taste perception, it... | 15024416 | PMC368160 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e64 |
Introduction
The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor found in a variety of vertebrate species. The AHR is a prototype member of the Per–Arnt–Sim (PAS) superfamily of signaling molecules. Members of this superfamily regulate cellular responses to a variety of environmental stimuli,... | 15024417 | PMC368161 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e65 |
As the year-long celebration of the 50th anniversary of the discovery of the structure of DNA came to an end, the engaging autobiography of one of the participants further enlivened the drama of this event. Maurice Wilkins, now 87, postpones the account of his involvement in the DNA affair until the second half of the ... | 0 | PMC368162 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e67 |
Symbiosis, an interdependent relationship between two species, is an important driver of evolutionary novelty and ecological diversity. Microbial symbionts in particular have been major evolutionary catalysts throughout the 4 billion years of life on earth and have largely shaped the evolution of complex organisms. End... | 15024418 | PMC368163 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Mar 16; 2(3):e68 |
Introduction
Wolbachia are intracellular gram-negative bacteria that are found in association with a variety of invertebrate species, including insects, mites, spiders, terrestrial crustaceans, and nematodes. Wolbachia are transovarialy transmitted from females to their offspring and are extremely widespread, having ... | 15024419 | PMC368164 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e69 |
Trace heavy metals are essential for a number of metabolic reactions in living systems, but cells walk a fine line between feast or famine. While iron, zinc, cobalt, and manganese, for example, contribute to the catabolic activity of enzymes involved in essential pathways from gene regulation to cell signaling, even a ... | 0 | PMC368165 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e70 |
Evolution is a complex phenomenon that requires a broad understanding of many areas of biology for us to appreciate it fully. Moreover, the field has expanded rapidly, especially since the development of molecular techniques in the past two to three decades. Futuyma's classic text on evolution (1998) contains 26 chapte... | 0 | PMC368166 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Mar 16; 2(3):e71 |
A substantial portion of research occurs in places where scholars congregate—in campus laboratories, in libraries, or in large specialized facilities, such as oceanographic ships, astronomical observatories, or accelerators. Under any of these circumstances, researchers can interact easily, exchanging ideas and informa... | 15024421 | PMC368167 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Mar 16; 2(3):e72 |
In 1959 Richard Feynman delivered what many consider the first lecture on nanotechnology. This lecture, presented to the American Physical Society at the California Institute of Technology, prompted intense discussion about the possibilities, or impossibilities, of manipulating materials at the molecular level. Althoug... | 15024422 | PMC368168 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e73 |
Introduction
During fetal development, the primary anatomical concentration of hematopoietic stem cells (HSCs) changes location several times. The migration of blood-borne progenitors is essential for the establishment of hematopoiesis in subsequent hematopoietic tissues (Moore and Metcalf 1970; Johnson and Moore 1975;... | 15024423 | PMC368169 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Mar 16; 2(3):e75 |
Wolbachia have a thing against males. A member of one of the most diverse groups of bacteria, called Proteobacteria, this parasitic “endosymbiont” lives inside the reproductive cells of a wide variety of the nearly 1 million species of arthropods, including insects, spiders, and crustaceans. It has also been found in w... | 0 | PMC368170 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 Mar 16; 2(3):e76 |
Introduction
Determining how information is “read out” of sensory maps in the cerebral cortex is of fundamental importance for understanding how neural activity gives rise to cognitive processes such as perception, planning for action, and working memory. A substantial portion of our knowledge about sensory read-out co... | 15024425 | PMC368171 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e77 |
Introduction
The dopamine transporter (DAT) plays a critical role in the synaptic clearance of dopamine (DA) by mediating the reuptake of DA released into the presynaptic terminal (Amara and Kuhar 1993; Giros and Caron 1993). It thereby regulates the strength and duration of the dopaminergic response. DAT is also the s... | 15024426 | PMC368172 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Mar 16; 2(3):e78 |
Introduction
The dynamic structure and physiology of a cell depend on coordinated synthesis, assembly, and localization of its macromolecular components (Orphanides and Reinberg 2002). The timing and level of expression of the genes that encode these components are controlled by transcription factors that regulate init... | 15024427 | PMC368173 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e79 |
Scientists searching for clues to our origins have long relied on studying fossils to piece together our evolutionary history. Now, with the tools of molecular genetics, they can reach beyond morphological evidence to retrieve traces of DNA preserved in the remnants of bone. And in these ancient DNA sequences, they're ... | 0 | PMC368174 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Mar 16; 2(3):e80 |
The single-celled Saccharomyces cerevisiae, commonly known as baker's yeast, measures just 2 microns—it takes about 4 billion to fill a teaspoon. But as a eukaryote (its cells have nuclei), its genes function in much the same way a human's do. For a gene to function, its DNA sequence must first be transcribed into RNA ... | 0 | PMC368175 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Mar 16; 2(3):e82 |
Of the 200-plus different types of cells that form the mammalian body, most have a finite life span. Like nearly everything in biology, there are exceptions—neurons and muscle cells, for example, can last a lifetime—but the vast majority of cells eventually wear out and must be replaced. Among the most short-lived cell... | 0 | PMC368176 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e83 |
Over the course of evolution, some organisms have gained many genes and become increasingly complex whereas other, simpler, organisms have survived with comparatively fewer genes. (Compare, for example, the 30,000 genes of humans to the 5,500 of brewer's yeast.) But where do these “new” genes come from? Evolutionary bi... | 0 | PMC368177 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Mar 16; 2(3):e84 |
To function properly, cells must keep constant tabs on the environmental conditions around them, such as the presence of growth hormones in the blood or the proximity of neighboring cells. These external cues are relayed into the cell through a cascade of chemical and physical reactions referred to as signal transducti... | 0 | PMC368178 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Mar 16; 2(3):e85 |
The notion of a neurally encoded “reward system” that reinforces pleasure-seeking behaviors first emerged fifty years ago. Psychologists James Olds and Peter Milner discovered this phenomenon when their “lack of aim” landed an electrode outside their target while studying the behavioral responses of rats given electric... | 0 | PMC368179 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Mar 16; 2(3):e87 |
The brain is an overwhelmingly complex organ packed with billions of nerve cells, performing a myriad of different functions. To decipher the roles of individual neurons in processing sensation or actions, scientists can measure the neural activity of animals that are shown particular objects or perform simple tasks. I... | 0 | PMC368180 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Mar 16; 2(3):e88 |
In PLoS Biology, volume 1, issue 1:
The Roles of APC and Axin Derived from Experimental and Theoretical Analysis of the Wnt Pathway
Ethan Lee, Adrian Salic, Roland Krüger, Reinhart Heinrich, Marc W. Kirschner
DOI: 10.1371/journal.pbio.0000010
Table 1: In the legend, the words fluxes and flux appeared without t... | 0 | PMC368181 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 Mar 16; 2(3):e89 |
Introduction
The aggregation of misfolded proteins underlies a diverse range of human diseases, including sporadic amyloidoses such as Alzheimer's disease and hereditary neuropathies such as Huntington's disease (Dobson 1999). Prions are a special class of protein aggregates that replicate their conformation and spread... | 15045026 | PMC374241 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Apr 23; 2(4):e86 |
For decades, scientists accepted that the nucleic acids, DNA and RNA, packed with thousands of protein-coding genes, were the sole purveyors of genetic information; all inherited traits, from eye color to shoe size, must be stored and expressed through nucleic acid mechanisms. But prions are an exception. These misshap... | 0 | PMC374242 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 23; 2(4):e93 |
Introduction
The human brain, particularly the cerebral cortex, has undergone a dramatic increase in its volume during the course of primate evolution, but the underlying molecular mechanisms that caused this expansion are not known. One approach shedding light on the molecular mechanisms of brain evolution is the anal... | 15045028 | PMC374243 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 May 23; 2(5):e126 |
Introduction
Histones are the major constituent of chromatin and exert a profound influence on most if not all aspects of chromosome behavior. The functional state of chromatin is regulated, in part, by histone modifying enzymes and ATP-dependent chromatin remodeling enzymes. Members of the latter enzyme class alter th... | 15045029 | PMC374244 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 23; 2(5):e131 |
Biologists have long known that the African great apes (including the chimpanzee, bonobo, and gorilla) are our closest relatives, evolutionarily speaking. The recent release of the chimp draft genome sequence confirms this relationship at the nucleotide level, showing that human and chimp DNA is roughly 99% identical. ... | 0 | PMC374245 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 23; 2(5):e134 |
When James Watson and Francis Crick reported the structure of DNA in 1953, the mechanism of inheritance was instantly apparent. The complementary pairing of the DNA bases in the double helix, the pair famously wrote, “immediately suggests a possible copying mechanism for the genetic material.” The structure helped expl... | 0 | PMC374246 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 May 23; 2(5):e136 |
Introduction
The number and type of genetic changes that control morphological and physiological changes during vertebrate evolution are not yet known. The evolutionary history of threespine sticklebacks (Gasterosteus aculeatus) provides an unusual opportunity to directly study the genetic architecture of adaptive dive... | 15069472 | PMC385219 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 May 30; 2(5):e109 |
The astounding diversity of life—different body shapes and sizes, physiologies, and behaviors—stems from the accumulation of genetic changes through the process we call evolution. But catching a glimpse into the process of evolution at the gene level is difficult, mostly because significant changes to the plant and ani... | 0 | PMC385220 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e143 |
Introduction
Microbes occupy almost every habitable niche in the biosphere, highlighting their enormous capability for adaptation and survival. This adaptive ability has been refined during millennia of evolution and has resulted in genes that evolve at very different rates. Some, such as housekeeping genes that code f... | 15094797 | PMC387263 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e81 |
Introduction
The identification of peptide epitopes associated with particular αβ T cell receptors (αβTCRs) is often still a bottleneck in studying T cells and their antigenic targets in, for example, autoimmunity, hypersensitivity, and cancer. A direct genetic or biochemical attack on this problem can be successful, e... | 15094798 | PMC387264 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e90 |
Introduction
The actin cytoskeleton determines the shape, mechanical properties, and motility of most eukaryotic cells. To change shape and to move, cells precisely control the location and timing of actin filament assembly by regulating the number of fast-growing (barbed) filament ends (Pollard et al. 2000). The actin... | 15094799 | PMC387265 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Apr 13; 2(4):e91 |
Microbes are arguably the most adaptable organisms on Earth, inhabiting nearly every crevice of nearly every corner of the globe. Some invade the cavities of a wide variety of insects and other invertebrates while others colonize the skin, blood, eyes, and internal organs of animals. Still others thrive in such inhospi... | 0 | PMC387266 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Apr 13; 2(4):e94 |
Introduction
Astrocytes are nonneuronal cells of the brain with some known and hypothesized functions (Kettenmann and Ransom 1995; Fields and Stevens-Graham 2002). Traditionally, astrocytes have been considered to mediate supportive and protective functions in the central nervous system because of their strategic place... | 15094801 | PMC387267 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e96 |
Introduction
According to legend, Archimedes shouted “Eureka!” (“I have found it!”) when he suddenly discovered that water displacement could be used to calculate density. Since then, “Eureka!,” or “Aha!,” has often been used to express the feeling one gets when solving a problem with insight. Insight is pervasive in h... | 15094802 | PMC387268 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e97 |
While we applaud PloS' use of Digital Object Identifiers (“The What and Whys of DOIs,” PLoS Biol 1: e57 doi: 10.1371/journal.pbio.0000057), we also note the lack of provisions in your instructions for authors for preserving access to electronic information residing at a cited Internet addresses via Uniform Resource Loc... | 15094803 | PMC387269 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Apr 13; 2(4):e99 |
As a student I always marvelled at the sight of single cells in culture moving over artificial surfaces and exhibiting membrane ruffles and protrusions. However, while I found cultured cells fascinating I always wondered how cells are able to move and regulate their shape in the context of a whole organism where so man... | 15094804 | PMC387270 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e100 |
Upon arrival from Europe, now more than two decades ago, I was taken aback by the level of violence in the American media. I do not just mean the daily news, even though it is hard getting used to multiple murders per day in any large city. No, I mean sitcoms, comedies, drama series, and movies. Staying away from Schwa... | 15094805 | PMC387271 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Apr 13; 2(4):e101 |
The capacity for self-generated movement is a defining characteristic of animal life. With the molecular components of cellular locomotion conserved in organisms from protozoa to vertebrates, directed cell motility appears to be an ancient cell process, likely dating back a billion years. Most directed motion relies on... | 0 | PMC387272 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 Apr 13; 2(4):e103 |
In the wake of declarations supporting open access to research literature from international bodies including the Organization for Economic Cooperation and Development (OECD) and the United Nations' World Summit on the Information Society (WSIS), advocates and critics of the movement appear to have agreed that the issu... | 15094807 | PMC387273 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e105 |
Introduction
A goal of primatology is to understand the enormous variability in primate social behavior. Early investigators examined interspecies differences, e.g., that pair-bonding is more common among arboreal than terrestrial primates (Crook and Gartlan 1966). Attention has also focused on geographical differences... | 15094808 | PMC387274 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Apr 13; 2(4):e106 |
Introduction
Predicting Patient Survival
When a patient is diagnosed with cancer, various clinical parameters are used to assess the patient's risk profile. However, patients with a similar prognosis frequently respond very differently to the same treatment. This may occur because two apparently similar tumors are actu... | 15094809 | PMC387275 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Apr 13; 2(4):e108 |
If you're one of those insufferable people who can finish the Saturday New York Times crossword puzzle, you probably have a gift for insight. The puzzles always have an underlying hint to solving them, but on Saturdays that clue is insanely obtuse. If you had all day, you could try a zillion different combinations and ... | 0 | PMC387276 | CC BY | 2021-01-05 08:21:08 | no | PLoS Biol. 2004 Apr 13; 2(4):e111 |
For the estimated 800 million people, living largely in developing countries, without enough food to eat, the main food risk is starvation. But if you ask, ‘When does food actually kill?’ in a country such as the United Kingdom, ‘Not that often’ is the short reply you would give after reading Hugh Pennington's book Whe... | 0 | PMC387277 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e112 |
It is becoming increasingly apparent that the vast blue expanse of ocean—the last frontier—is not as inexhaustible as it once seemed. While we have yet to fully explore the reaches of the sea, technology has granted humans the ability to harvest its wealth. We can now fish anywhere, at any depth, for any species. Like ... | 15094811 | PMC387278 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e113 |
Did you ever wish you could peek inside someone's brain and see what was going on in there? In research reported in this issue of PLoS Biology, Hajime Hirase and his colleagues at Rutgers University have done just that by focusing their microscope on the brains of living rats in order to examine how certain cells calle... | 0 | PMC387279 | CC BY | 2021-01-05 08:21:14 | no | PLoS Biol. 2004 Apr 13; 2(4):e115 |
Doctors and researchers often look for the rapid proliferation of T cell populations, key defensive players in the immune system, as a telltale sign that the body is working hard to fend off a foreign threat. Every one of these circulating white blood cells carries a T cell receptor (TCR) that binds to a specific prote... | 0 | PMC387280 | CC BY | 2021-01-05 08:21:14 | no | PLoS Biol. 2004 Apr 13; 2(4):e117 |
After the recent mad cow scare in the United States, 61% of Americans said they would start eating more fish, according to a Wall Street Journal Online poll. The respondents may not know that populations of large predatory fish, such as tuna, swordfish, and marlin, have declined 90% over the past 50 years or that less-... | 0 | PMC387282 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e119 |
Introduction
Marine organisms serve as hosts for a diversity of parasites and pathogens. Mortalities affect not only the host population, but can cascade through ecosystems. Loss of biologically engineered habitats such as seagrass beds (Lewis 1933; Taylor 1933) and cascading trophic effects due to removal of consumers... | 15094816 | PMC387283 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e120 |
In 1967, mule deer in a research facility near Fort Collins, Colorado, in the United States apparently began to react badly to their captivity. At least, that was the guess of researchers working on the natural history and nutrition of the deer, which became listless and showed signs of depressed mood, hanging their he... | 15094817 | PMC387284 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e121 |
The need for effective communication of research and the promotion of science is more important then ever. Public scepticism of research is high, and the number of students studying science continues to dwindle. In an attempt to combat this, the University of Edinburgh encourages its Ph.D. students to participate in a ... | 15094818 | PMC387285 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e122 |
Many damaged and mutant polypeptides, as well as some normal proteins, have a tendency to aggregate in cells. Some protein aggregates are capable of “dividing” and propagating in cells, leading to formation of similar aggregates in daughter cells or even in neighboring cells due to “infection.” These self-propagating p... | 15094820 | PMC387287 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e125 |
Cancer specialists often talk about cancer as an umbrella term for over 200 different diseases, each having unique characteristics. But even these categories are too broad, as the same type of cancer can take very different paths in different people. It's not uncommon, for example, for a tumor to grow aggressively in o... | 0 | PMC387822 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Apr 13; 2(4):e118 |
For most animal species, behavioral attributes are largely the product of interactions between genes and environment, with behavioral patterns preserved by natural selection. Birds, for example, know instinctively what type of nest to build for their offspring; salamanders don't need lessons to swim. But when it comes ... | 0 | PMC387823 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Apr 13; 2(4):e124 |
Introduction
The draft sequences of the human, mouse, and rat genomes are already available (Lander et al. 2001; Marshall 2001; Venter et al. 2001; Waterston et al. 2002). The next challenge comes in the understanding of basic human molecular biology through interpretation of the human genome. To display biological dat... | 15103394 | PMC393292 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Jun 20; 2(6):e162 |
The announcement of the human genome sequence three years ago was widely hailed as one of the great scientific achievements in modern history, and with good reason. Determining the structure and nature of the genetic code promises to provide valuable insights into human evolution and the molecular basis of disease. But... | 0 | PMC393293 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 Jun 20; 2(6):e166 |
Introduction
Stochasticity is a ubiquitous characteristic of life. Such apparent randomness, or “noise,” can be observed in a wide range of organisms, resulting in phenomena ranging from progressive loss of cell-cycle synchronization in an initially synchronized population of microbes to the pattern of hair coloration ... | 15124029 | PMC400249 | CC BY | 2021-01-05 08:26:25 | no | PLoS Biol. 2004 Jun 27; 2(6):e137 |
Introduction
Vertebrate development results from a series of cell–cell interactions in which groups of cells induce their neighbors to acquire new cell differentiation fates. This process, known as embryonic induction, was first reported for the induction of the lens in surface ectoderm by the optic vesicles originatin... | 15138495 | PMC406387 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e92 |
Introduction
Cellular response to DNA damage requires the coordinated activation of cell cycle checkpoints with DNA repair (Zhou and Elledge 2000). Failure to block S-phase entry in response to damaged DNA or to repair the DNA leads to genomic instability, the hallmark of cancer cells. DNA double-strand breaks (DSBs) a... | 15138496 | PMC406388 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e110 |
In what is usually referred to as the most famous experiment in embryology, Hans Spemann and Hilde Mangold (1924) showed that a specific region in early frog embryos called the blastopore lip can induce a second complete embryonic axis, including the head, when transplanted to a host embryo. Most of the axis, including... | 15138497 | PMC406389 | CC0 | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e127 |
Introduction
Complex intracellular networks inform a cell's developmental and growth decisions in response to external nutrients or signaling molecules. Defining the topology of such networks has generally relied on combinations of genetic epistasis and biochemical techniques to establish the linear order of components... | 15138498 | PMC406390 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e128 |
Introduction
The genetic programs and developmental processes that lead to organ formation are still poorly understood. We are currently witnessing an expansion in research that aims to identify the genes responsible for the structural development of organs and their later function. Among the organs of the body, the he... | 15138499 | PMC406391 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e129 |
Introduction
Skeletal muscle regeneration has long been considered to be mediated solely by monopotential skeletal muscle stem cells known as satellite cells (Bischoff 1994; Charge and Rudnicki 2004). However, recent studies have identified novel populations of adult stem cells in skeletal muscle. For example, “side-po... | 15138500 | PMC406392 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 May 11; 2(5):e130 |
Introduction
Advances in microarray technology have made the systematic study of expression levels of thousands of transcripts possible. This has been heralded as a major step forward in understanding the function of genomes, since transcript expression levels are expected to correlate with biological functions. Althou... | 15138501 | PMC406393 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e132 |
Although the word ‘revolution’ should not be used lightly in science, there is no other way to describe the recent explosion in our awareness and understanding of RNA-mediated gene silencing pathways. The central player in RNA-mediated gene silencing is a double-stranded RNA (dsRNA) that is chopped into tiny RNAs by th... | 15138502 | PMC406394 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e133 |
If the United States' Human Cloning Prohibition Act of 2003 (H.R. 534) becomes law, American researchers practicing any form of cloning could face up to ten years in prison and a minimum $1 million fine. The bill criminalizes a research procedure, called somatic cell nuclear transfer, that involves removing the DNA fro... | 0 | PMC406395 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e135 |
The heart starts beating and pumps blood through the body long before it has achieved its mature architecture. In theory, this provides a chance for cardiac function to sculpt cardiac structure, an intriguing possibility for developmental biologists, and one of potentially great clinical import for cardiologists seekin... | 0 | PMC406396 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e138 |
Introduction
The zebrafish (Danio rerio) has long been used as a model organism for the identification of genes required for early vertebrate development (Kimmel 1989). There is reason to believe that the zebrafish can also be used in genetic screens to identify cancer genes. Zebrafish can live for 4–5 y (Gerhard et al... | 15138505 | PMC406397 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 May 11; 2(5):e139 |
One of the hallmarks of human nature is our remarkably flexible behaviour, especially in the social domain, which is perhaps also a major reason for our relative evolutionary success. Our social skills are already being honed in childhood and early adolescence, when we quickly become very adept at forming and breaking ... | 15138506 | PMC406398 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e140 |
With billions of cells in the adult human body, all replicating and dividing in an environment laden with toxins, radiation, and free radicals, a certain amount of DNA damage is guaranteed to occur. Fortunately, all organisms have built-in checkpoints throughout the cell cycle that prevent such mistakes from propagatin... | 0 | PMC406399 | CC BY | 2021-01-05 08:21:15 | no | PLoS Biol. 2004 May 11; 2(5):e144 |
The next generation of life scientists are currently undergraduates—and the success of this generation depends upon the quality of the education they receive. It is clear the expectations for undergraduate education are changing (Collins et al. 2003). When the National Research Council published its recommendations for... | 15138508 | PMC406400 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e145 |
“… a complete, comprehensive understanding of odor … may not seem a profound enough problem to dominate all the life sciences, but it contains, piece by piece, all the mysteries.” — Lewis Thomas
One of the oldest beliefs about human perception is that we have a poor sense of smell. Not only is this a general belief a... | 15138509 | PMC406401 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 May 11; 2(5):e146 |
This book, the latest in the excellent Monographs in Population Biology series from Princeton University Press, is a work of advocacy in which the authors argue that evolutionary theory is incomplete and that, in consequence, we are failing fully to understand phenomena as disparate as ecosystem development and the int... | 0 | PMC406402 | CC BY | 2021-01-05 08:21:09 | no | PLoS Biol. 2004 May 11; 2(5):e147 |
Francis Hamilton, the Briton who first described zebrafish (Danio rerio) in 1822, would be astounded to see the scientific attention now afforded to this two-inch-long native of Indian rivers. A fish with no economic worth was how he described this little creature. Yet recently, the European Union awarded 12 million Eu... | 15138510 | PMC406403 | CC BY | 2021-01-05 08:21:15 | no | PLoS Biol. 2004 May 11; 2(5):e148 |
Formation of the central nervous system has long been thought to result from an induction process, whereby signals emanating from a portion of the dorsal endomesoderm (the inner middle layer of the developing embryo), known as the Spemann–Mangold organizer, instruct cells of the overlying dorsal ectoderm (outer layer) ... | 0 | PMC406404 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e149 |
An organism's survival depends on developing effective strategies for identifying and adapting to available sources of food. Even organisms as small as the budding yeast Saccharomyces cerevisiae can respond in a complex way to the presence of different energy sources. While yeast can metabolize many different sugars, g... | 0 | PMC406405 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e151 |
Are evolutionary changes in gene expression determined mostly by natural selection or by random forces? It's been some 150 years since Charles Darwin proposed that organisms adapt to their environment through the process of natural selection, yet the debate still rages, particularly at the molecular level. Darwinian se... | 0 | PMC406406 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e154 |
This is the second in a series of three editorials that aim to address recurring concerns about the benefits and risks associated with open-access publishing in medicine and the biological sciences.
Scientific societies serve their members, their broader scholarly communities, and the different components of their mi... | 15138514 | PMC406407 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e156 |
To investigate the genetic underpinnings of a particular biological process, geneticists screen large collections of mutant organisms to characterize their physical defects. By comparing the genetic makeup of nonmutant (called wild-type) organisms to mutants, it's possible to tease out the genes responsible for a defec... | 0 | PMC406408 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e159 |
Science looks set for a fundamentalist revival within the European Union. Its leading proponents are taking advantage of unprecedented political upheaval—as ten new Member States accede to the Union—to press their case for funding of basic research that is driven solely and independently by investigators themselves in ... | 15138516 | PMC406409 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e161 |
In PLoS Biology, volume 2, issue 3:
Table of Contents
Page iii
This photograph was used on the March 2004 Table of Contents, where Adam Lazarus, who generously supplied the image, should have been acknowledged. We apologize for this omission. | 0 | PMC406410 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 May 11; 2(5):e201 |
Background
The increasing density in the woody component of savannas has been widely reported [1-5] with special mention being made of Acacia karroo Hayne [6,7] and A. nilotica (L.) Willd. Ex Del. subsp. kraussiana (Benth.) Brenan, [8,9]. in some areas, as major contributors to the phenomenon. In Hluhluwe-iMfolozi Park... | 15068486 | PMC406512 | CC BY | 2021-01-04 16:29:14 | no | BMC Ecol. 2004 Apr 7; 4:3 |
All organisms have evolved complex mechanisms designed to exquisitely regulate the expression of appropriate genes at their correct levels. Natural random variation in the processes of regulation and expression, however, limits the precision with which protein production can be controlled. This subtle variation, or “no... | 0 | PMC406520 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 27; 2(6):e191 |
Introduction
The network responsible for segment polarity in the Drosophila melanogaster embryo has been extensively studied. The segment polarity pattern emerges from a sequence of developmental events that each refine the pattern produced by the previous event. During the early cell cycles of the embryo, cell divisio... | 15208707 | PMC423129 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e123 |
Introduction
Generally, the number of plant and animal species declines as one moves away from the equator (Pianka 1966; Stevens 1989, 1992; Rohde 1992; Brown 1995; Kaufman 1995; Rosenzweig 1995; Roy et al. 1998; Huston 1999; Chown and Gaston 2000; Hawkins and Porter 2001). This pattern, known as the latitudinal specie... | 15208708 | PMC423130 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e141 |
Introduction
Reproductive isolation is the most commonly used criterion to define species. Hybrid incompatibilities (HIs) such as hybrid sterility and lethality are widely observed examples of reproductive isolation. The Dobzhansky-Muller (D-M) model explains how the genes causing deleterious phenotypes in hybrids can ... | 15208709 | PMC423131 | CC BY | 2021-01-05 08:21:11 | no | PLoS Biol. 2004 Jun 15; 2(6):e142 |
Functional magnetic resonance imaging—fMRI—opens a window onto the brain at work. By tracking changes in cerebral blood flow as a subject performs a mental task, fMRI shows which brain regions “light up” when making a movement, thinking of a loved one, or telling a lie. Its ability to reveal function, not merely struct... | 15208710 | PMC423132 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 Jun 15; 2(6):e150 |
Introduction
Biochemical studies performed in higher eukaryotes have shown that DNA replication initiates at specific sites, or within initiation zones, suggesting the involvement of particular DNA sequences called replicators (reviewed by DePamphilis 1999). In contrast, functional studies, as well as studies of DNA re... | 15208711 | PMC423133 | CC BY | 2021-01-05 08:21:11 | no | PLoS Biol. 2004 Jun 15; 2(6):e152 |
Introduction
Integrins are major metazoan cell adhesion receptors that have the distinctive property of transducing signals across the plasma membrane in both directions. Intracellular binding of cytoskeletal components to integrin cytoplasmic domains activates the ligand binding competency of the extracellular domain ... | 15208712 | PMC423134 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e153 |
Introduction
Recombination is a fundamental biological feature about which we still know remarkably little, especially in mammals. Understanding recombination is also of practical importance for evolutionary inference and human genetics (Nachman 2002; Arnheim et al. 2003). Unfortunately, the process is difficult to stu... | 15208713 | PMC423135 | CC BY | 2021-01-05 08:26:26 | no | PLoS Biol. 2004 Jun 15; 2(6):e155 |
Because of the explosive growth in our scientific understanding, today's students are required to learn and maintain a rapidly expanding knowledge base. Students are also expected to understand and follow the crossover of information between different disciplines. As a result, they often have to understand the fundamen... | 15208714 | PMC423136 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e157 |
Introduction
About half of the expected mitochondrial proteins in humans are known to date, and already a fifth of these known proteins are associated with human Mendelian disorders (Online Mendelian Inheritance in Man [http://www.ncbi.nlm.nih.gov/Omim/]; DiMauro and Schon 1998; Andreoli et al. 2004). Mitochondrial cor... | 15208715 | PMC423137 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e160 |
Introduction
Central to the study of neuronal networks is the simultaneous measurement of activity at many locations. While important results have been obtained using multiple patch recordings (Stuart et al. 1993; Markram 1997; Markram et al. 1997) and microelectrode arrays (Meister et al. 1994), patch recordings are l... | 15208716 | PMC423138 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e163 |
Why is the sky blue? Any scientist will answer this question with a statement of mechanism: Atmospheric gas scatters some wavelengths of light more than others. To answer with a statement of purpose—e.g., to say the sky is blue in order to make people happy—would not cross the scientific mind. Yet in biology we often p... | 15208717 | PMC423139 | CC BY | 2021-01-05 08:21:11 | no | PLoS Biol. 2004 Jun 15; 2(6):e164 |
Nearly 150 years after Darwin published On the Origin of Species, biologists are still debating how new species emerge from old—and even the definition of species itself. Darwin demurred from offering a hard and fast definition, suggesting that such a thing was “undiscoverable.” One of the more enduring definitions cha... | 0 | PMC423140 | CC BY | 2021-01-05 08:21:10 | no | PLoS Biol. 2004 Jun 15; 2(6):e165 |
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