Is it a revolution?

Jablonka and Lamb's claim that evolutionary biology is undergoing a ‘revolution’ is queried. But the very concept of revolutionary change has uncertain application to a field organized in the manner of contemporary biology. The explanatory primacy of sequence properties is also discussed.

Here a virus, there a virus, everywhere the same virus?

There are an estimated 10(31) viruses on Earth, most of which are phages that infect bacteria. Metagenomic analyses have shown that environmental viral communities are incredibly diverse. There are an estimated 5000 viral genotypes in 200 liters of seawater and possibly a million different viral genotypes in one kilogram of marine sediment. By contrast, some culturing and molecular studies have found that viruses move between different biomes. Together, these findings suggest that viral diversity could be high on a local scale but relatively limited globally. Also, by moving between environments, viruses can facilitate horizontal gene transfer.     

The gill of fish larvae. Is it primarily a respiratory or an ionoregulatory structure?

Based on surface area and chloride cell number, rainbow trout Oncorhynchus mykiss gills appear initially to be more important in terms of ion balance than gas exchange. Chloride cells appear on the gill 3–6 days before hatch at 10°C. This is about 9 days before secondary lamellae, the definitive adult gas exchange structure, begin to form. At hatch, 22% of all chloride cells but only 7% of total surface area are located on the gill. This discrepancy gradually diminishes but even at complete yolk absorption the gill still seems to be about twice as important in terms of ion balance (75% of chloride cells) as gas exchange (37% of total surface area represented by gill filaments and lamellae combined). Surface area measurements and chloride cell counts reported in the literature for larvae of other species show a similar pattern suggesting that this may be a general phenomenon. If true, the implications are profound not only for developmental physiologists but also for those interested in the evolutionary history of gills and their function in adult fish.     

The nature of chiral recognition: Is it a three-point interaction?

Evolution of the initial “three-point attachment model” resulted in the understanding that an interaction in at least three configuration-dependent points is needed for a chiral selector to recognize entantiomers. Thermodynamic enantioselectivity of this interaction can result in chiral discrimination of the enantiomers, with the exception of a temperature range where enthalpic and entropic contributions to the free energy of discrimination balance each other. Similarly, a three-point interaction is needed for a chiral inductor to modify enantiospecifically a prochiral molecule. The difference between a theoretical interaction point and real interaction sites in chemical molecules is emphasized. The role of conformational rigidity of chiral species is discussed in relation to the dependence of spatial arrangement of three active points on the configuration of the species. Chirality 9:99–102, 1997. © 1997 Wiley-Liss, Inc.     

Is it a paradox or misinterpretation?

The paradox recently raised by Wang and Yuan (Proteins 2000;38:165-175) in protein structural class prediction is actually a misinterpretation of the data reported in the literature. The Bayes decision rule, which was deemed by Wang and Yuan to be the most powerful method for predicting protein structural classes based on the amino acid composition, and applied by these investigators to derive the upper limit of prediction rate for structural classes, is actually completely the same as the component-coupled algorithm proposed by previous investigators (Chou et al., Proteins 1998;31:97-103). Owing to lack of a complete or near-complete training data set, the upper limit rate thus derived by these investigators might be both invalid and misleading. Clarification of these points will further stimulate investigation of this interesting area.     

Is parainfluenza virus a threatening virus for human cancer cell lines?

Immortalized cell lines, such as human cancer cell lines, are an indispensable experimental resource for many types of biological and medical research. However, unless the cell line has been authenticated prior to use, interpretation of experimental results may be problematic. The potential problems this may cause are illustrated by studies in which authentication of cell lines has not been carried out. For example, immortalized cell lines may unknowingly be infected with viruses that alter their characteristics. In fact, parainfluenza virus type 5 (PIV5) poses a threat to the use of immortalized cell lines in biological and medical research; PIV5 infection significantly alters cellular physiology associated with the response to interferon. If PIV5 infection is widespread in immortalized cell lines, then a very large number of published studies might have to be re-evaluated. Fortunately, analyses of a large number of immortalized cell lines indicate that PIV5 infection is not widespread.     

Is sleeping sickness a circadian disorder? The serotonergic hypothesis.

Patients with human African trypanosomiasis (HAT, sleeping sickness), due to the inoculation of Trypanosoma brucei gambiense or rhodesiense by the tsetse fly, are "sleepy by day and restless by night." The first 24 h polysomnographic recording (electroencephalogram [EEG], electromyogram [EMG], electrooculogram [EOG]), showing a disappearance of the 24 h rhythmicity of sleep and wakefulness, was performed in 1988. Thereafter, our team recorded 18 patients and 6 control volunteers at bed rest during 24 h sessions. Blood samples were taken hourly from 8 of the patients through a venous catheter and every 10 minutes from the remaining 10 patients. Plasma cortisol, prolactin, growth hormone (GH), melatonin, and plasma renin activity were analyzed. No disruptions of the circadian rhythms of sleep and wakefulness were described in the 6 healthy African subjects, and there also were no disturbances of 24 h hormone profiles. The patients experienced a dysregulation of the circadian rhythmicity of sleep and wakefulness that was proportional to the severity of the disease. Sleep onset rapid eye movement (REM) episodes were more frequent in the most severely sick patients, who also showed major disruptions in the 24 h plasma hormonal profiles, with intermediate profiles being observed at earlier stages of the sickness. However, the relationship between hormonal secretions and the states of vigilance persisted. Contrary to the other hormones, melatonin secretion remained undisturbed. These findings indicate that, at the stage of meningoencephalitis, HAT represents a dysregulation of the sleep-wake cycle and sleep structure, rather than a hypersomnia; this dysregulation is proportional to the degree of severity of the clinical and biological symptoms. It is accompanied by a circadian dysrhythmia of hormonal secretions, although the relationship between hormone pulses and sleep states is preserved. We therefore favor the involvement of the serotonergic raphe nuclei-suprachiasmatic nuclei liaison in the reversible disturbance of the circadian rhythms of the sleep-wake cycle and of hormonal secretions.     

Is gibbon ape leukaemia virus still a threat?

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The Florey Lecture, 1990. How is the cell division cycle regulated?

It is argued in this lecture that in most eukaryotic cells onset of mitosis is coupled to attainment of a critical cell mass and to completion of the previous S-phase. In fission yeast these controls operate through a regulatory gene network that activates the p34cdc2 protein kinase at mitosis. This is brought about by dephosphorylation of a tyrosine residue located in the ATP binding site of the kinase. The p34cdc2 protein kinase is also important for regulating the onset of mitosis in vertebrate cells suggesting that there is a universal control regulating mitosis in all eukaryotic cells.     

The tropical rain forest: Is it a productive environment for human foragers?

A recent debate in ecological anthropology concerns the availability of wild foods for human foragers in tropical forests. This article is a response to the five essays in this same issue of Human Ecology that examine the hypothesis that hunter-gatherers could never have lived in tropical rain forest without direct or indirect access to cultivated foods. We clarify the hypothesis and assess the evidence offered to date. Archeological evidence suggests foraging without cultivation in Malaysia. We propose a program of ecological studies and archeological research which, if undertaken, should provide the evidence necessary to falsify the hypothesis.     

Is there a role for actin in virus budding?

Electrophoretic data from both sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE) and acid-urea gels reveal a protein in purified murine mammary tumor virus (MuMTV) which co-migrates with purified chick skeletal muscle actin. 125I-labeling of intact and disrupted virus preparations shows that the actin-like protein is not artifactually adsorbed to the outside of virions during isolation. Quantitative SDS- PAGE and examination of negatively stained preparations show that the actin cannot be accounted for by a contaminating population of virus- free vesicles. The ultrastructure of mammary epithelial cells and of Rous sarcoma virus-transformed chick embryo fibroblasts shows that virus extrusion is associated with filament-containing cellular processes. In particular, MuMTV is released from the ends of long microvilli which contain a bundle of 6-8-nm microfilaments and share other structural features with intestinal microvilli. We suggest that virus nucleoids require an interaction with host cell contractile proteins for their extrusion from the cell.     

Is it functional?

This report describes the first scientific meeting of the British Society for Proteome Research (BSPR), which was organised jointly with the European Bioinformatics Institute (EBI) and held in July 2004. The focus of the conference was functional proteomics with an emphasis on possible clinical application. The main subjects described here are: the need to simplify samples, the use of biological fluids versus tissue, consideration of biological and experimental variation and the creation of databases to achieve meaningful functional analysis.