Novel gene acquisition on carnivore Y chromosomes

Despite its importance in harboring genes critical for spermatogenesis and male-specific functions, the Y chromosome has been largely excluded as a priority in recent mammalian genome sequencing projects. Only the human and chimpanzee Y chromosomes have been well characterized at the sequence level. This is primarily due to the presumed low overall gene content and highly repetitive nature of the Y chromosome and the ensuing difficulties using a shotgun sequence approach for assembly. Here we used direct cDNA selection to isolate and evaluate the extent of novel Y chromosome gene acquisition in the genome of the domestic cat, a species from a different mammalian superorder than human, chimpanzee, and mouse (currently being sequenced). We discovered four novel Y chromosome genes that do not have functional copies in the finished human male-specific region of the Y or on other mammalian Y chromosomes explored thus far. Two genes are derived from putative autosomal progenitors, and the other two have X chromosome homologs from different evolutionary strata. All four genes were shown to be multicopy and expressed predominantly or exclusively in testes, suggesting that their duplication and specialization for testis function were selected for because they enhance spermatogenesis. Two of these genes have testis-expressed, Y-borne copies in the dog genome as well. The absence of the four newly described genes on other characterized mammalian Y chromosomes demonstrates the gene novelty on this chromosome between mammalian orders, suggesting it harbors many lineage-specific genes that may go undetected by traditional comparative genomic approaches. Specific plans to identify the male-specific genes encoded in the Y chromosome of mammals should be a priority.     

Two decades of macrophyte expansion on the shores of a large shallow northern temperate lake—A retrospective series of satellite images

We made use of a 22-year (1985-2007) retrospective archive of moderate resolution Landsat TM and ETM+ satellite images to estimate the changes in cover of emergent macrophytes in the large shallow eutrophic Lake Võrtsjärv (270 km²) in Estonia. An original non-parametric image interpretation methodology was applied on late summer images. The combined GIS and statistical analysis of 217 coastal sections showed that the helophytic macrophyte belt, dominated by common reed (Phragmites australis), has rapidly widened during the last two decades, with an average expansion rate of 2.2 m per year. Statistical model revealed that the vicinity of large inflows had the strongest positive effect on the expansion of macrophytes, on average 1.6 times. In some sub-regions of the lake shore, we found the suppressing effect of the presence of small inflows on the change of helophytic belt width. This effect, however, was probably interconnected with the presence of human activity at the shoreline, which itself had statistically near-marginal suppressing effect on the widening of the reed belt.We showed that medium resolution satellite images can successfully be used for the retrospective monitoring of macrophyte vegetation in the littoral zone of large water bodies by applying very simple image classification methodology. As the lake coastal areas showed a tendency to become overgrown with reed and other macrophytes even in conditions of generally reduced agricultural intensity in the catchment area, we hypothesize that the clonal expansion of reed is probably triggered by the complex of drivers: large seasonal fluctuations in the water level create specific low water conditions in estuaries in combination with nutrients supply resolved from lake bottom or brought by rivers. Estuary areas are characterised by mineral sediments suitable for anchoring and protection-provision against destructive wave- and ice-action.Probably the most efficient biodiversity conservation policy to revealed macrophytic expansion is the reactivation of disrupted management activities along the coastline.     

Diversity in gas exchange and muscular activity patterns in insects studied by a respirometer-actograph

Different events in insect gas exchange and muscular activity are described by a new system of automatic respirometers, a differential electrolytic microrespirometer-actograph. This is very sensitive to volumetric changes caused by insect respiration and/or body movements. In this system, oxygen generation and its regulation are combined in the same current circuit. According to this principle, the oxygen consumed by the insect is continuously replaced by equal amounts of electrolytically produced oxygen. This simple laboratory-made apparatus records simultaneously metabolic rate, the cyclicity of external gas exchange, rhythms of muscular ventilating and the pattern of other body movements, including abdominal pulsations not observable with the naked eye. The respirometer-actograph described here is applicable also to the recording of the respiration of other terrestrial arthropods or other living organisms or tissues.     

Studies in African thelephoroid fungi: 1. <Emphasis Type="Italic">Tomentella capitata</Emphasis> and <Emphasis Type="Italic">Tomentella brunneocystidia</Emphasis>, two new species from Benin (West Africa) with capitate cystidia

This paper presents Tomentella capitata and Tomentella brunneocystidia as new species based on molecular data and anatomical features. Both T. capitata and T. brunneocystidia form sister species with Tomentella pilosa. All three taxa are well supported by bootstrap values. Anatomically, T. capitata and T. brunneocystidia are very close and are similar in shape, size, ornamentation of basidiospores, and size and colour of subicular hyphae. Monomitic rhizomorphs sometimes covered by irregularly shaped thin hyphae are present in both species. Shape and pigmentation of the cystidia are the most discriminating features between T. capitata and T. brunneocystidia. The cystidia of T. capitata are maximum 35 μm long, show a distinctive globose apex and are sometimes covered with dark brown pigmentation and/or encrustation, whereas cystidia of T. brunneocystidia are bigger, up to 55 μm long, with a sub-capitate shape and dark blue to dark green contents all over their length. The differences to species, already described as having capitate and clavate cystidia, are discussed. A key for the identification of cystidioid Tomentella species is given. Taxonomical novelties: Tomentella capitata Yorou & Agerer, Tomentella brunneocystidia Yorou & Agerer.