Multiple interspecies transmissions of human and simian T-cell leukemia/lymphoma virus type I sequences

Using two sets of nucleotide sequences of the human and simian T-cell leukemia/lymphoma virus type I (HTLV-I/STLV-I), one consisting of 522 bp of the env gene from 70 viral strains and the other a 140-bp segment from the pol gene of 52 viral strains, I estimated cladograms based on a statistical parsimony procedure that was developed specifically to estimate within-species gene trees. An extension of a nesting procedure is offered for sequence data that forms nested clades used in hypothesis testing. The nested clades were used to test three hypotheses relating to transmission of HTLV/STLV sequences: (1) Have cross-species transmissions occurred and, if so, how many? (2) In what direction have they occurred? (3) What are the geographic relationships of these transmission events? The analyses support a range of 11-16 cross-species transmissions throughout the history of these sequences. Additionally, outgroup weights were assigned to haplotypes using arguments from coalescence theory to infer directionality of transmission events. Conclusions on geographic origins of transmission events and particular viral strains are inconclusive due to small samples and inadequate sampling design. Finally, this approach is compared directly to results obtained from a traditional maximum parsimony approach and found to be superior at establishing relationships and identifying instances of transmission.      

长春净月潭地区土壤跳虫的生态分布

土壤动物直接参与土壤形成,它与土壤微生物的相互配合,对植物凋落物的分解起着十分重要的作用。土壤跳虫是土壤动物中最重要的类群之一。关于它的生态分布,目前国内报道不多。东北师范大学和日本九州大学合作,对长春净月潭地区的土壤跳虫进行了初步调查。     

The mutation rates of di-, tri- and tetranucleotide repeats in Drosophila melanogaster

In a recent study, we reported that the combined average mutation rate of 10 di-, 6 tri-, and 8 tetranucleotide repeats in Drosophila melanogaster was 6.3 x 10(-6) mutations per locus per generation, a rate substantially below that of microsatellite repeat units in mammals studied to date (range = 10(-2)-10(-5) per locus per generation). To obtain a more precise estimate of mutation rate for dinucleotide repeat motifs alone, we assayed 39 new dinucleotide repeat microsatellite loci in the mutation accumulation lines from our earlier study. Our estimate of mutation rate for a total of 49 dinucleotide repeats is 9.3 x 10(-6) per locus per generation, only slightly higher than the estimate from our earlier study. We also estimated the relative difference in microsatellite mutation rate among di-, tri-, and tetranucleotide repeats in the genome of D. melanogaster using a method based on population variation, and we found that tri- and tetranucleotide repeats mutate at rates 6.4 and 8.4 times slower than that of dinucleotide repeats, respectively. The slower mutation rates of tri- and tetranucleotide repeats appear to be associated with a relatively short repeat unit length of these repeat motifs in the genome of D. melanogaster. A positive correlation between repeat unit length and allelic variation suggests that mutation rate increases as the repeat unit lengths of microsatellites increase.      

Low population genetic structuring of two cryptic bat species suggests their migratory behaviour in continental Europe

Although two cryptic pipistrelle bat species, Pipistrellus pipistrellus and Pipistrellus pygmaeus , belong among the most common bat species in Europe, it is still unclear whether they can migrate over long distances between summer and winter roosts. Long-distance migratory species may be expected to show low levels of genetic structuring in large areas due to regular mixing of the gene pool by mating that occurs during migration and/or hibernation. Conversely, the dispersal of gametes in sedentary species is spatially restricted, populations are more genetically structured, and isolation by relatively short distance is visible. By analysing diversity of highly variable microsatellites within and among summer colonies of both studied species in central Europe, we found that differentiation between populations is very weak. Both classical F _ST and Bayesian clustering approach failed to detect genetic structure among colonies and there was no significant isolation-by-distance pattern. The analyses of relatedness, however, revealed that individuals within colonies are more related than random suggesting philopatry of at least one sex. The results were very similar for the two species. The high level of gene flow among central European populations, even on large geographic distances, is discussed in relation with migrations, dispersal, and mating behaviour.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 103–114.     

A NEW METHOD FOR THE EXTRACTION OF MACROFOSSILS FROM CALCAREOUS ROCKS USING SULPHURIC ACID

Abstract:  A new method for the extraction of calcified and/or partly pyritized macrofossils has been developed. This method is based upon the differential speeds for the dissolving of microcrystalline and macrocrystalline calcite in 38% sulphuric acid. The effectiveness of the sulphuric acid treatment is also influenced by the volume of clay minerals in the host rock. Therefore, this method is highly applicable for the extraction of macrofossils from marlstones, marly limestones, and other lithified calcareous sediments. The main advantages of this method, when compared with other chemical methods, are (1) the short treatment time, (2) the capability of dissolving the sediment on the fossil's surface, and (3) its efficiency in dissolving calcareous rocks with low porosity. This method has been successfully applied to Upper Cretaceous macrofossils from the Bohemian Cretaceous Basin. The surface of extracted macrofossils remained undamaged, exhibiting minute skeletal details; perhaps even encrusters and bioerosions.     

The palatability of flavoured novel floating pellets made with brewer's spent grain to captive carp

Abstract

The palatability to common carp, Cyprinus carpio L. of three newly developed differently flavoured floating pellets made from a high proportion (40%) of brewer's spent grain (BSG) was tested using a multiple-offer feeding experiment. The addition of ‘bold’ flavours, such as vanilla or strawberry essence, may help mask the unpleasant taste of some piscicides; however, their inclusion must not compromise uptake by carp. There were no significant differences between the consumption rates of the three varieties, and all flavours were readily consumed. Therefore, it is suggested that highly flavoured pellets made with BSG have a strong potential to mask the flavour of an unpalatable toxin, and further research is now needed to test this hypothesis.