Calcium signalling: more messengers,more channels,more complexity

Recent studies have expanded the number of channel types and messengers that lead to Ca(2+) signals within cells. Furthermore, we are beginning to understand the complex interplay between different sources of Ca(2+).     

Antarctic teleost immunoglobulins: more extreme, more interesting

We have investigated the immunoglobulin molecule and the genes encoding it in teleosts living in the Antarctic seas at the constant temperature of −1.86 °C. The majority of Antarctic teleosts belong to the suborder Notothenioidei (Perciformes), which includes only a few non-Antarctic species. Twenty-one Antarctic and two non-Antarctic Notothenioid species were included in our studies. We sequenced immunoglobulin light chains in two species and μ heavy chains, partially or totally, in twenty species. In the case of heavy chain, genomic DNA and the cDNA encoding the secreted and the membrane form were analyzed. From one species, Trematomus bernacchii, a spleen cDNA library was constructed to evaluate the diversity of VH gene segments. T. bernacchii IgM, purified from the serum and bile, was characterized. Homology Modelling and Molecular Dynamics were used to determine the molecular structure of T. bernacchii and Chionodraco hamatus immunoglobulin domains. This paper sums up the previous results and broadens them with the addition of unpublished data.     

A foot more light, a step more true

Thulborn, T. 190: Dinosaur Tracks.
Gillette, D. D. & Lockley, M. G. (eds.) 1989: Dinosaur Tracks and Trores     

真菌系统学大趋势：越来越多的分类单元

分子生物学技术与真菌系统学的有机融合,为真菌分类和系统发育研究带来了革命性的变化。最近20年来,真菌学家们建立了大量的新目、新科、新属和新种,掀开了真菌多样性及其起源进化研究的新纪元,但很多重要的系统发育问题仍没有解决,特别是大量目间、科间的亲缘关系并不清楚。细分是真菌系统学的主流趋势,野生食用菌和毒蘑菇的分类也是如此,近年涌现了越来越多的新分类单元,如在2010-2019年的10年间,中国发表大型真菌（含地衣）新种1 240余个。本专刊收载的15篇论文是对我国野生食用菌和毒蘑菇研究工作的部分总结,对真菌资源利用、毒蘑菇中毒预防与治疗具有较重要的科学意义和应用价值。     

Harvested populations are more variable only in more variable environments

The interaction between environmental variation and population dynamics is of major importance, particularly for managed and economically important species, and especially given contemporary changes in climate variability. Recent analyses of exploited animal populations contested whether exploitation or environmental variation has the greatest influence on the stability of population dynamics, with consequences for variation in yield and extinction risk. Theoretical studies however have shown that harvesting can increase or decrease population variability depending on environmental variation, and requested controlled empirical studies to test predictions. Here, we use an invertebrate model species in experimental microcosms to explore the interaction between selective harvesting and environmental variation in food availability in affecting the variability of stage‐structured animal populations over 20 generations. In a constant food environment, harvesting adults had negligible impact on population variability or population size, but in the variable food environments, harvesting adults increased population variability and reduced its size. The impact of harvesting on population variability differed between proportional and threshold harvesting, between randomly and periodically varying environments, and at different points of the time series. Our study suggests that predicting the responses to selective harvesting is sensitive to the demographic structures and processes that emerge in environments with different patterns of environmental variation.     

The more insect trypanosomatids under study-the more diverse Trypanosomatidae appears

From 10 trypanosomatids genera six comprise monogenetic parasites of insects and for the rest of four genera insects may serve as vectors. The invertebrate host is an essential element of trypanosomatids life cycle, but from more than 900 recognised vertebrate hosts only about 500 species of insects have been discovered to be the hosts of homoxenous trypanosomatids. Nothing or very little is known about insect trypanosomatids in many extensive areas such as South East Asia, Australia, Japan and some others. Each new region explored brings many new findings. Recently flagellates were found in new insect species and families. The border of parasites distribution was expanded till Central Asia, Far East and North over the Polar Circle. As paleogeographical events are now under contemplating in trypanosomatids phylogeny researches so northern insect trypanosomatids may attract some attention as the elements of postglacial fauna which is definitely young. Very broad host specificity of insect trypanosomatids and high probability to isolate non-specific parasite show causes that only the investigation of a culture may solve the question 'what parasite was really isolated?'. Examination of cell morphotypes in the host has clearly demonstrated that they are not sufficient for classification and may lead us to be mistaken. The number of insect trypanosomatid cultures is inadequate for characterisation of the diversity of insects trypanosomatids. Trypanosoma is actually the only trypanosomatid genus which is out of questions. Insect trypanosomatids comprise the most diversified part of trypanosomatids evolutionary tree. Recent ssrRNA phylogenetic analysis and morphological data show that three insect isolates represent new lineages on trypanosomatid evolutionary tree, as well as dendrograms derived from PCR data demonstrated some new groups of isolates. Therefore, the more insect trypanosomatids are involved in laboratory investigations--the more new clusters or/and new lineages are appearing on the tree.     

PTENless means more

Recent studies indicate that certain key molecules that are vital for various developmental processes, such as Wnt, Shh, and Notch, cause cancer when dysregulated. PTEN, a tumor suppressor that antagonizes the PI3 kinase pathway, is the newest one on the list. The biological function of PTEN is evolutionarily conserved from C. elegans to humans, and the PTEN-controlled signaling pathway regulates cellular processes crucial for normal development, including cell proliferation, soma growth, cell death, and cell migration. In this review, we will focus on the function of PTEN in murine development and its role in regulating stem cell self-renewal and proliferation. We will summarize the organomegaly phenotypes associated with Pten tissue-specific deletion and discuss how PTEN controls organ size, a fundamental aspect of development. Last, we will review the role of PTEN in hormone-dependent, adult-onset mammary and prostate gland development.     

Mice and more

A report on the Mouse Initiatives V meeting 'Genomics of Complex Systems in Biomedical Research', The Jackson Laboratory, Bar Harbor, USA, 30 July-2 August 2003.     

When more is less: the fitness consequences of predators attacking more unpalatable prey when more are presented

In 1879, Fritz Müller hypothesized that mimetic resemblance in which defended prey display the same warning signal would share the costs of predator education. Although Müller argued that predators would need to ingest a fixed number of prey with a given visual signal when learning to avoid unpalatable prey, this assumption lacks empirical support. We report an experiment which shows that, as the number of unpalatable prey presented to them increased, avian predators attacked higher numbers of those prey. We calculated that, when predators increase attacks, the fitness costs incurred by unpalatable prey can be substantial. This suggests that the survival benefits of mimicry could be lower than Müller proposed. An important finding is, however, that these costs decline in importance as the total number of available prey increases.