SNARE Proteins-Why So Many,Why So Few?

Abstract: Both trafficking and secretion critically depend on accurate and specific membrane recognition and fusion. A key step in these processes is the assembly of a complex consisting of a small number of proteins, i.e., the exocytic core complex. In nerve terminals, this set consists of VAMP and synaptotagmin, which reside at membranes of synaptic vesicles, and syntaxin and SNAP-25 at the plasma membrane. In this survey, different secretory systems that depend on the exocytic core proteins are considered. The possibility that specificity in membrane recognition and fusion is achieved by the numerous variants of proteins of the exocytic core is discussed. Variability of the core complex proteins is determined by the complexity of gene families, isoform-specific localization, and posttranslational modifications. Basic biochemical properties depend on specific isoforms, and the possible protein-protein interactions are determined, in turn, by the compatibility of different isoforms. A correlation between specific variants and distinct biochemical or cellular properties is shown. The outcome of this survey is that heterogeneity in secretion may be dictated by the large number of possible combinations of variants of only a few proteins.     

Why Are There So Many Waterfowl and So Few Northern Bobwhites? Rethinking Federal Coordination

In this paper we ask whether we should we re-examine the future of upland gamebird management and greater federal oversight and partnerships in the twenty-first century. Management for waterfowl in North America has been successful because of the 1918 Migratory Bird Treaty Act (MBTA) and the subsequent 1986 North American Waterfowl Management Plan (NAWMP). Although the MBTA included most migratory and non-migratory species, upland gamebirds, including the northern bobwhite (Colinus virginianus; bobwhite), were excluded and retained under state control. Although many waterfowl populations have been increasing, bobwhite populations have declined precipitously during much of the period. Excluding non-migratory gamebirds from the MBTA meant that the multistate coordinating efforts that made the MBTA successful for increasing the management of waterfowl have not been applied. The National Bobwhite Conservation Initiative (NBCI) has made a strong effort to unite states within the bobwhite range but does not have the federal anchoring and financial support that were given to states by the MBTA and NAWMP and currently integrate adaptive harvest, habitat management, and financial partnerships to acquire and manage wetlands that support waterfowl production. The NBCI Coordinated Implementation Program (CIP) is designed to serve the function of developing and monitoring habitat for bobwhites but is entirely voluntary and dependent entirely on state and non-governmental organization (NGO) funds, lacking federal grants and Federal Duck Stamp funds. To catch up with the successes of waterfowl, we discuss the implications of increasing coordination, partnerships, and funding mechanisms between the federal government, state governments, and NGOs to provide common landscape-level population monitoring and modeling, adaptive harvest regulations, habitat management goals, and a national upland gamebird stamp. © 2021 The Wildlife Society.     

So what if parasites vary?

The British Society for Parasitology Autumn Symposium was held on 14 September 2001 at the Linnean Society of London, UK, only a few yards from the room in which Darwin and Wallace presented their joint papers on organic variation. Fittingly, the symposium--Parasite variation: immunological and ecological significance--considered the consequences of parasite variation.     

So what do your sugars do?

Up to about fifteen years ago the above question was quite often asked of glycoconjugates enthusiasts. It was always a silly question, the answer being ‘How many doings do you want to hear about?’ Since then our understanding of the structures, biosynthesis and varied functions of the glycoconjugates has developed incredibly and come to have a major impact on much of present-day biological and medical research.     

So you think you can edit?

This article presents one scientist''s perspective on the transition from life at the bench to an editorial career.     

So,why is water biologically important?

Some brief impressionistic and necessarily subjectively based comments on the content of the Discussion Meeting are made. It is pointed out that the principal thrust of most of the presentations was directed towards structural aspects of proteins in various media. Comments are also made on the necessary interplay between the medium in which biomolecules occur and the interatomic forces between the atoms comprising the biomolecules. Some speculation is made on the possibility of life-forms existing in extreme environments.     

So do we understand how enzymes work?

Between 1930 and 1975 biochemical and structural analysis of enzymes led to a clear set of ideas that might form a basis for detailed understanding of enzyme action. Further development required energetic and thermodynamic analysis of enzymes in an aqueous medium, beyond the computational power then available. Structural enzymology advanced in other directions, but the fundamental questions of enzyme action must soon be re-opened.     

So, you want to work in industry?

Once upon a time ... Industry was seen as a poor second choice for those who could not find a niche in academia. That time has passed and an increasing amount of leading-edge research is done in the laboratories of Industry. So what is it like in the world of Industry--and what sort of biologists does Industry need?     

Why Are There So Many Diverse Replication Machineries?

The replicon model has initiated a major research line in molecular biology: the study of DNA replication mechanisms. Until now, the majority of studies have focused on a limited set of model organisms, mainly from Bacteria or Opisthokont eukaryotes (human, yeasts) and a few viral systems. However, molecular evolutionists have shown that the living world is more complex and diverse than believed when the operon model was proposed. Comparison of DNA replication proteins in the three domains, Archaea, Bacteria, and Eukarya, have surprisingly revealed the existence of two distinct sets of non-homologous cellular DNA replication proteins, one in Bacteria and the other in Archaea and Eukarya, suggesting that the last universal common ancestor possibly still had an RNA genome. A major puzzle is the presence in eukaryotes of the unfaithful DNA polymerase alpha (Pol α) to prime Okazaki fragments. Interestingly, Pol α is specifically involved in telomere biosynthesis, and its absence in Archaea correlates with the absence of telomeres. The recent discovery of telomere-like GC quartets in eukaryotic replication origins suggests a link between Pol α and the overall organization of the eukaryotic chromosome. As previously proposed by Takemura, Pol α might have originated from a mobile element of viral origin that played a critical role in the emergence of the complex eukaryotic genomes. Notably, most large DNA viruses encode DNA replication proteins very divergent from their cellular counterparts. The diversity of viral replication machineries compared to cellular ones suggests that DNA and DNA replication mechanisms first originated and diversified in the ancient virosphere, possibly explaining why they are so many different types of replication machinerie.     

Why Are Computational Neuroscience and Systems Biology So Separate?

Despite similar computational approaches, there is surprisingly little interaction between the computational neuroscience and the systems biology research communities. In this review I reconstruct the history of the two disciplines and show that this may explain why they grew up apart. The separation is a pity, as both fields can learn quite a bit from each other. Several examples are given, covering sociological, software technical, and methodological aspects. Systems biology is a better organized community which is very effective at sharing resources, while computational neuroscience has more experience in multiscale modeling and the analysis of information processing by biological systems. Finally, I speculate about how the relationship between the two fields may evolve in the near future.     

Replication Origins: Why Do We Need So Many?

During the G1 phase of the cell cycle, replication origins are prepared to fire, a process that is referred to as origin licensing. It was often pondered what a cell’s fate would be if not all of its replication origins were licensed and subsequently activated during S phase. One obvious prediction was that S phase would simply be prolonged. As it turns out, however, the consequences are much more complex. A short G1 phase enforced by premature entry into S phase, or other events that negatively affect origin licensing, will ultimately compromise the cell’s ability to complete DNA replication before entering mitosis. As a result, the cell becomes genomically unstable when it attempts to repair unreplicated DNA during anaphase. Thus, the density of active replication origins in the chromosomes of eukaryotic cells determines S phase dynamics and chromosome stability during mitosis.     

So what is a species anyway? A primatological perspective

Since Darwin's time, the question “what a species” has provoked fierce disputes and a tremendous number of publications, from short opinion papers to thick volumes. 1 The debates covered fundamental philosophical questions, such as: Do species exist at all independently of a human observer or are they just a construct of the human mind to categorize nature's organismic diversity and serve as a semantic tool in human communication about biodiversity? 2 - 4 or: Are species natural kinds (classes) or individuals that are “born” by speciation, change in course of time, and finally “die” when they go extinct or diverge into new species? 5 - 8 Also included was the problem of species as taxa (taxonomic) versus species as products of the speciation process (evolutionary). 9 More pragmatic issues arose, such as: How can we reliably delineate and delimitate species? 10 , 11 The great interest in what a species is reflects the importance of “species” as fundamental units in most fields of biology, especially evolutionary biology, ecology, and conservation. 2 , 12 - 14