Do bacteria have sex?

Do bacteria have genes for genetic exchange? The idea that the bacterial processes that cause genetic exchange exist because of natural selection for this process is shared by almost all microbiologists and population geneticists. However, this assumption has been perpetuated by generations of biology, microbiology and genetics textbooks without ever being critically examined.     

Do tastants have a smell?

The stimuli used in taste research are usually considered to be odourless. This was tested in two experiments with aqueous solutions of two representative compounds for each of the five taste qualities including umami. In the first experiment elderly and young subjects rated the intensity and pleasantness of three concentrations of the stimuli, while wearing or not wearing a noseclip. Saliva production was also measured. Blocking olfaction only influenced salivation for umami. It reduced taste intensity ratings, but as in an earlier experiment with the same compounds in food products, this effect was stronger in the young, who also liked the stimuli better wearing the noseclip. In the second experiment, another group of young people tried to detect the odours of the tastants dissolved in demineralized, double-distilled or Evian water. A considerable number of subjects could regularly detect seven of the ten tastants by olfaction and the extent to which they did correlated significantly with the reduction in taste intensity ratings for the different tastants found in the first experiment. We suggest that most tastants can be smelled and that this smell contributes to taste intensity ratings.     

Why have organelles retained genomes?

The observation that chloroplasts and mitochondria have retained relics of eubacterial genomes and a protein-synthesizing machinery has long puzzled biologists. If most genes have been transferred from organelles to the nucleus during evolution, why not all? What selective pressure maintains genomes in organelles? Electron transport through the photosynthetic and respiratory membranes is a powerful - but dangerous - source of energy. Recent evidence suggests that organelle genomes have persisted because structural proteins that maintain redox balance within bioenergetic membranes must be synthesized when and where they are needed, to counteract the potentially deadly side effects of ATP-generating electron transport.     

Do hornets have zombie workers?

Colonies of the European hornet, Vespa crabro, are typically founded by a single queen mated to a single male. From the resulting colony relatedness pattern we predicted strong worker-queen conflict over male production where both the workers and the queen attempt to produce the colony's males. To test for this conflict, male production was studied in 15 hornet nests using a combination of DNA microsatellite analysis (282 males), worker ovary dissections (500 workers from eight nests) and 50 h of observation (four nests). In contrast to our prediction, the data show that hornet males are queens' sons, that workers never attempt to lay eggs, rarely have activated ovaries, and that there is no direct aggression between the queen and the workers. This contrasts with other data for vespine wasps, which support relatedness predictions. Dolichovespula arenaria has the same kin structure as V. crabro and workers produce males in many colonies. The similarity between these two species makes it difficult to explain why workers do not reproduce in V. crabro. Self-restraint is expected if worker reproduction significantly reduces colony productivity but there is no obvious reason why this should be important to V. crabro but not to D. arenaria. Alternatively, queen control may be important. The absence of expressed queen-worker conflict rules out physical control. Indirect pheromonal control is a possibility and is supported by the occurrence of royal courts and queen pheromone in Vespa but not Dolichovespula. Pheromonal queen control is considered evolutionarily unstable, but could result from a queen-worker arms race over reproductive control in which the queen is ahead. The genetic data also revealed diploid males in one colony, the first example in the vespine wasps, and two colonies with double matrilines, suggesting that occasional usurpation by spring queens occurs.     

Do the eyes have it?

Since Btt last examined the iris and retina markets, demand has grown, the technology has improved, new players have entered the arena and new products have been developed. For the first time ever, Btt is devoting a complete survey to these two very different methods of recognising an individual by the unique patterns within parts of their eye.     

Why do microorganisms have aquaporins?

Aquaporins are channel proteins that enhance the permeability of cell membranes for water. They have been found in Bacteria, Archaea and Eukaryotes. However, their absence in many microorganisms suggests that aquaporins do not fulfill a broad role such as turgor regulation or osmoadaptation but, instead, fulfill a role that enables microorganisms to have specific lifestyles. The recent discovery that aquaporins enhance cellular tolerance against rapid freezing suggests that they have ecological relevance. We have identified several examples of large-scale freeze-thawing of microbes in nature and we also draw attention to alternative lifestyle-related functions for aquaporins, which will be a focus of future research.     

Do mitochondria have an immune system?

The question if mitochondria have some kind of immune system is not trivial. The basis for raising this question is the fact that bacteria, which are progenitors of mitochondria, do have an immune system. The CRISPR system in bacteria based on the principle of RNA interference serves as an organized mechanism for destroying alien nucleic acids, primarily those of viral origin. We have shown that mitochondria are also a target for viral attacks, probably due to a related organization of genomes in these organelles and bacteria. Bioinformatic analysis performed in this study has not given a clear answer if there is a CRISPR-like immune system in mitochondria. However, this does not preclude the possibility of mitochondrial immunity that can be difficult to decipher or that is based on some principles other than those of CRISPR.     

Does my mouse have Alzheimer's disease?

Small animal models that manifest many of the characteristic neuropathological and behavioral features of Alzheimer's disease (AD) have been developed and have proven of great value for studying the pathogenesis of this disorder at the molecular, cellular and behavioral levels. The great progress made in our understanding of the genetic factors that either cause or contribute to the risk of developing AD has prompted many laboratories to create transgenic (tg) mice that overexpress specific genes which cause familial forms of the disease. Several of these tg mice display neuropathological and behavioral features of AD including amyloid β-peptide (Aβ) and amyloid deposits, neuritic plaques, gliosis, synaptic alterations and signs of neurodegeneration as well as memory impairment. Despite these similarities, important differences in neuropathology and behavior between these tg mouse models and AD have also been observed, and to date no perfect animal model has emerged. Moreover, ascertaining which elements of the neuropathological and behavioral phenotype of these various strains of tg mice are relevant to that observed in AD continues to be a challenge. Here we provide a critical review of the AD-like neuropathology and behavioral phenotypes of several well-known and utilized tg mice that express human APP transgenes.     

Do big females have big pelves?

Previous studies have shown that maternal stature is a correlate of both pelvic size and reproductive efficiency. This study addresses the issue of body size and obstetric advantage. The relationship between pelvic size and three nonpelvic measures of body size is determined for females and males. The skeletal sample consists of blacks, whites, and Native Americans. The variables include 28 measures of the pelvis, length and head diameter of the femur, and clavicular length. The coefficient of multiple determination (CMD) is computed for each pelvic measure using multiple regression, with the three nonpelvic measures serving as the independent variables. Partial correlation coefficients are also calculated between each pelvic and nonpelvic variable, while controlling for the other two nonpelvic variables. The results show that all CMDs in females and all but one CMD in males are "low," i.e., below 33%. The sexes are nonsignificantly different in their CMDs for 22 of the 28 pelvic variables; of the six variables that are significantly different, five are of the midplane. The sexes are also broadly comparable in their partial correlations. The results are explained as follows. First, the concordance between the sexes in the relationship between pelvic size and nonpelvic measures of body size is due to their genetic similarity for homologous structures. Second, as pelvic size is at the minimum at the midplane, the sexual differences in CMDs are the result of selection with respect to obstetrics. Third, four explanations for the low CMDs are discussed: 1) lack of populationally or racially specific analysis; 2) nonlinear relationship between pelvic size and nonpelvic measures of body size; 3) combination of negative allometric selection between newborn body weight and maternal stature and weight with positive selection for maternal pelvic size; and 4) hormonally induced increase in pelvic capacity during parturition.     

Do organisms have an ontological status?

The category "organism" has an ambiguous status: is it scientific or is it philosophical? Or, if one looks at it from within the relatively recent field or sub-field of philosophy of biology, is it a central, or at least legitimate category therein, or should it be dispensed with? In any case, it has long served as a kind of scientific bolstering for a philosophical train of argument which seeks to refute the mechanistic or reductionist trend, which has been perceived as dominant since the 17th century, whether in the case of Stahlian animism, Leibnizian monadology, the neo-vitalism of Hans Driesch, or, lastly, of the "phenomenology of organic life" in the 20th century, with authors such as Kurt Goldstein, Maurice Merleau-Ponty, and Georges Canguilhem. In this paper I try to reconstruct some of the main interpretive stages or layers of the concept of organism in order to evaluate it critically. How might organism be a useful concept if one rules out the excesses of organismic biology and metaphysics? Varieties of instrumentalism and what I call the projective concept of organism are appealing, but perhaps ultimately unsatisfying.     

What have we learnt from SARS?

With outbreaks of infectious disease emerging from animal sources, we have learnt to expect the unexpected. We were, and are, expecting a new influenza A pandemic, but no one predicted the emergence of an unknown coronavirus (CoV) as a deadly human pathogen. Thanks to the preparedness of the international network of influenza researchers and laboratories, the cause of severe acute respiratory syndrome (SARS) was rapidly identified, but there is no complacency over the global or local management of the epidemic in terms of public health logistics. The human population was lucky that only a small proportion of infected persons proved to be highly infectious to others, and that they did not become so before they felt ill. These were the features that helped to make the outbreak containable. The next outbreak of another kind of transmissible disease may well be quite different.     

Did trypanosomatid parasites have photosynthetic ancestors?

Some molecular phylogenies of plastid-like genes suggest that chloroplasts (the structures responsible for photosynthesis in plants and algae) might have been secondarily lost in trypanosomatid parasites. Chloroplasts are present in some euglenids, which are closely related to trypanosomatids, and it has been argued that chloroplasts arose early in the diversification of the lineage Euglenozoa, to which trypanosomatids and euglenids belong (plastids-early hypothesis). This article reviews how euglenid ultrastructural systems are functionally integrated and phylogenetically correlated. I argue that chloroplast acquisition profoundly altered the structure of certain euglenids, and that the complete absence of these modifications in other euglenozoans is most consistent with their never having had a chloroplast. Ultrastructural evidence suggests that chloroplasts arose relatively recently within a specific subgroup of euglenids and that trypanosomatids are not secondarily non-photosynthetic (plastids-recent hypothesis).     

Does FSH signaling have a gender?

FSH is the main endocrine control of mammalian reproduction. FSH triggers somatic cells of the gonads which support germ cells metabolically, i.e. Sertoli cells of the seminiferous tubules, and granulosa cells harboring the oocyte, within the ovarian follicle. FSH leads to similar biological responses in both cell types since it stimulates proliferation and differentiation, according to the developmental stage. However, FSH receptor knock-out female mice are infertile, unlike male mice. Hence, FSH is not equally important in both sexes. Nevertheless, does FSH induce distinct signalling mechanisms in its target cells ? Here, we compare the signalling mechanisms induced by FSH in ovarian and testicular physiology.     

Does zoo herpetology have a future?

Fifty-two North American zoo reptile and amphibian departments were surveyed to determine their contributions to recognized American Zoo and Aquarium Association (AZA)-sponsored programs and formalized research projects over the past 10 years. Surveys also requested information concerning the allocation of resources for conservation and research programs, staff educational background, and entry level salaries. Twenty-two institutions responded to the survey, collectively indicating a total of 164 technical papers, 16 field studies, and 101 non-technical articles completed between 1987 and 1997. Of the 164 technical papers published, 130 (79%) were contributed by three institutions. Of the 16 field studies, seven were outside the United States, whereas nine focused on native species and ecosystems. Six of the reported field studies involved only financial or logistical support. Of the 101 non-technical articles, 42 (42%) were contributed by a single institution. Twenty-one formalized in-house research projects were reported. However, only four appeared to have a clearly defined objective. Survey respondents also reported nine species of reptiles and one amphibian taxon are managed by Species Survival Plans (SSPs). There are currently 12 Taxon Advisory Group (TAG) coordinators, with four of the current coordinators having served on multiple TAG committees. There are 41 AZA-approved studbooks for reptiles and two for amphibians, with 29 having actually been published to date. The average starting salary reported in our survey for entry level keeper positions was $19,500 (range, $13,500–30,000). The average level of education reported was high school graduate. There was no correlation between productivity and higher wages, or level of education. Only one institution received funding specifically for research. We conclude that zoo herpetology departments are not realizing their potential for formalized research and conservation projects and propose recommendations for future involvement. Zoo Biol 17:453–462, 1998. © 1998 Wiley-Liss, Inc.