Murine Leukaemia C-type Virus associated with Functional Murine Carcinomas of Endocrine Origin

The discovery of C-type viral particles related to murine leukaemia virus in two different mouse tumour cell types is indirect support for the “oncogene” hypothesis.     

Volumen und Proteinsynthese der Kerne des Stratum Basale in der Stumpfepidermis während des Wundverschlusses nach Amputation der Vorderextremität bei Triturus vulgaris

After injection of tritiated phenylalanine, microautoradiographs of longitudinal sections of the stumps of the forelegs of Triturus vulgairs 1 hour, 2, 3 and 9 hours after amputation and also of the opposite limb (reference) were prepared for quantitative measurements. The epidermal tissue (stratum basale) was examined with regard to proximo-distal changes of nuclear volume and protein synthesis. In the stratum basale of the stump the values for the parameters examined were similar to those of the reference limbs 1h and 2h after amputation, but 3h and 9h after amputation areas of increased nuclear volume were observed as well as an increased rate of protein synthesis per unit of nuclear volume. Protein synthesis in the epidermis of the stump was extremely low 1h after amputation. Protein synthesis in the reference epidermis was also reduced at this time, but then increased although the nuclear volume remained constant.     

Effect of some disaccharides, hexoses and pentoses on nitrate reductase, glutamine synthetase and glutamate dehydrogenase in excised pea roots

The effects of exogenous sucrose, lactose, d -glucose, d (-)fructose, d -galactose, d -mannose, l -sorbose, l -arabinose and d -xylose on nitrate reductase (NR), glutamine synthetase (GS) and glutamate dehydrogenase (GDH) levels, on anaerobic nitrite production and on respiratory O₂ consumption were studied in excised roots of pea (Pisum sativum L. cv. Raman). Sucrose, glucose and fructose increase NR and GS levels and decrease GDH level (when compared with roots cultures without any sugar) at all concentrations used, but the extent of this effect varies. NR induction is enhanced by all sugars within the concentration range studied. Precultivation of roots with mannose and galactose results in an increase in anaerobic nitrite production in a medium consisting of phosphate buffer and KNO₃. GS reaches its maximum at lower sugar concentrations, this fact being especially clear-cut with galactose. The decrease in GS level observed in roots cultured without sucrose is enhanced by higher sorbose concentrations. The increase in GDH level occurring in roots cultured without sucrose is depressed by low galactose and mannose concentrations but enhanced by high galactose, mannose, xylose and a wide range of sorbose concentrations. Lactose exerts only slight influence on the enzymes. The effects of sugars are in no case consistent with their effect on respiratory O₂ consumption which is most pronounced with NR. The above results show that the effects of sugars on NR, GS and GDH are not mediated by one universal mechanism.     

Climate–growth relationships of tropical tree species in West Africa and their potential for climate reconstruction

Most tropical regions are facing historical difficulties of generating biologically reconstructed long‐term climate records. Dendrochronology (tree‐ring studies) is a powerful tool to develop high‐resolution and exactly dated proxies for climate reconstruction. Owing to the seasonal variation in rainfall we expected the formation of annual tree rings in the wood of tropical West African tree species. In the central‐western part of Benin (upper Ouémé catchment, UOC) and in northeastern Ivory Coast (Comoé National Park, CNP) we investigated the relationship between climate (precipitation, sea surface temperature (SST)) and tree rings and show their potential for climate reconstruction. Wood samples of almost 200 trees belonging to six species in the UOC and CNP served to develop climate‐sensitive ring‐width chronologies using standard dendrochronological techniques. The relationship between local precipitation, monthly SST anomalies in the Gulf of Guinea, El Niño‐ Southern Oscillation (ENSO) and ring‐width indices was performed by simple regression analyses, two sample tests and cross‐spectral analysis. A low‐pass filter was used to highlight the decadal variability in rainfall of the UOC site. All tree species showed significant relationships with annual precipitation proving the existence of annual tree rings. ENSO signals could not be detected in the ring‐width patterns. For legume tree species at the UOC site significant relationships could be found between SST anomalies in the Gulf of Guinea indicating correlations at periods of 5.1–4.1 and 2.3 years. Our findings accurately show the relationship between tree growth, local precipitation and SST anomalies in the Gulf of Guinea possibly associated with worldwide SST patterns. A master chronology enabled the reconstruction of the annual precipitation in the UOC to the year 1840. Time series analysis suggest increasing arid conditions during the last 160 years which may have large impacts on the hydrological cycles and consequently on the ecosystem dynamics and the development of socio‐economic cultures and sectors in the Guinea‐Congolian/Sudanian region.     

Alpine headwater streams as reservoirs of remnant populations of the Danubian clade of brown trout

1. The watercourses of Austria are mainly part of the Danube drainage system. Nonetheless, only few brown trout (Salmo trutta) populations of the Danubian phylogenetic lineage have been found in this region, not being introgressed by hatchery‐reared fish of the allochthonous Atlantic lineage. The present study was aimed at identifying further waterbodies that might harbour the non‐admixed gene pool of the Danubian clade trout. 2. In a first step, the complete mitochondrial DNA control region of 447 specimens from 20 sampling sites was sequenced to screen for the presence of specific haplotypes. In a second step, 332 individuals from 15 populations were analysed at 10 microsatellite DNA loci. 3. Although sampling concentrated on remote Alpine headwater streams, introgression of hatchery strains was more common than expected from existing stocking records. For seven populations, however, no evidence of recent hatchery trout introgression was found and it is suggested that they might represent the indigenous gene pool. 4. Populations showing no evidence of hatchery introgression displayed lower levels of intrapopulation variability and higher degrees of differentiation compared to purported admixed populations. 5. Our study demonstrates the necessity of combining different molecular markers to reveal the impact of introgression into wild populations, since at some sampling sites admixture would have remained undetected if only a single molecular technique was applied. 6. The identification and characterisation of non‐introgressed populations provides important information for setting conservation priorities and preventing further loss of genetic integrity of a unique element of the native fish fauna.     

Phenetic studies of African army ant queens of the genus Dorylus (Hymenoptera: Formicidae)

Multivariate analyses of queens of fourteen species of the Old World army ant genus Dorylus were undertaken to assist in clarifying the status of the six included subgenera. Results were compared with two similar studies based on major workers and males, respectively. Queens are phenetically less divergent than either of the other two phena examined, although similar sub-generic relationships were observed. Taken together, these phenetic studies suggest that the subgenera Rhogmus and Alaopone are deserving of continued individual status, but that species of Anomma and Dorylus (s.s.) form one diverse taxon. A conservative classification would place Dichthadia and Typhlopone species together with the composite Dorylus (s.s.) - Anomma taxon.     

Carcass maintenance and biparental brood care in burying beetles: are males redundant?

1. Burying beetles inter small vertebrate carcasses that ultimately serve as a food source for their developing young. The male remains with the female on the carcass after the brood has been produced, purportedly to aid in the feeding and protection of larvae. However, numerous laboratory experiments have failed to demonstrate a beneficial effect of the male on the growth and survival of offspring.
2. A potential difficulty with laboratory studies is that beetles are typically held under relatively benign conditions, protected from the biotic and environmental challenges that they normally encounter. In nature, males may enhance offspring survival by aiding the female in ridding the carcass of mould, and by helping to preserve the carcass through the secretion of antibiotic substances in the beetles' saliva. To examine more rigorously the potential benefits of male parental care, an experiment was conducted under field conditions in which the reproductive output of male–female pairs was compared to that of single females.
3. Beetles were induced to bury carcasses in soil inside rigid plastic tubes that had been inserted into the ground. The experiment was a paired design involving pairs of sisters reproducing in adjacent tubes; one sister reproduced alone, whereas the other reproduced with the assistance of a male. Soil cores were recovered about 1 month later, and examined for viable pupae.
4. There was no significant difference in the number of offspring produced by single females and those reproducing with the assistance of the male, nor was there any significant difference in total brood mass. These results suggest that any benefits of extended male residency on the carcass do not stem from male participation in carcass maintenance or provisioning young.