Root vole movement patterns: do ditches function as habitat corridors?

1. Ditches are often connected to root vole habitat patches (i.e. moist reed patches) in the Netherlands. Due to the linear structure of ditches and because ditch habitat is qualitatively similar to root vole habitat patches, we hypothesized that ditches could function as habitat corridors facilitating dispersal movement of root voles. In order to test this hypothesis, we radiotracked root voles released in a landscape novel to them, consisting of ditches and agricultural meadows.
2. Agricultural meadows often surround the marsh patches inhabited by root voles. As the meadows are mowed regularly, we included the length of the meadow vegetation as an experimental factor in the study.
3. Assuming that ditches function as habitat corridors, we expected root voles in the ditches to move faster and more unidirectionally than root voles in the meadows, and to prefer the ditches to meadows.
4. We found that the ditches did not facilitate faster movements than the meadows. Although the root voles moved back and forth within the ditches, they showed a more directional movement pattern than the root voles in the meadows. Furthermore, the root voles preferred the ditch habitat irrespective of the vegetative cover in the meadow.
5. We conclude that ditches could function as habitat corridors for root voles, as they preferred to move in ditches when in unfamiliar areas.     

Shared genetic loci between depression and cardiometabolic traits

Epidemiological and clinical studies have found associations between depression and cardiovascular disease risk factors, and coronary artery disease patients with depression have worse prognosis. The genetic relationship between depression and these cardiovascular phenotypes is not known. We here investigated overlap at the genome-wide level and in individual loci between depression, coronary artery disease and cardiovascular risk factors. We used the bivariate causal mixture model (MiXeR) to quantify genome-wide polygenic overlap and the conditional/conjunctional false discovery rate (pleioFDR) method to identify shared loci, based on genome-wide association study summary statistics on depression (n = 450,619), coronary artery disease (n = 502,713) and nine cardiovascular risk factors (n = 204,402–776,078). Genetic loci were functionally annotated using FUnctional Mapping and Annotation (FUMA). Of 13.9K variants influencing depression, 9.5K (SD 1.0K) were shared with body-mass index. Of 4.4K variants influencing systolic blood pressure, 2K were shared with depression. ConjFDR identified 79 unique loci associated with depression and coronary artery disease or cardiovascular risk factors. Six genomic loci were associated jointly with depression and coronary artery disease, 69 with blood pressure, 49 with lipids, 9 with type 2 diabetes and 8 with c-reactive protein at conjFDR < 0.05. Loci associated with increased risk for depression were also associated with increased risk of coronary artery disease and higher total cholesterol, low-density lipoprotein and c-reactive protein levels, while there was a mixed pattern of effect direction for the other risk factors. Functional analyses of the shared loci implicated metabolism of alpha-linolenic acid pathway for type 2 diabetes. Our results showed polygenic overlap between depression, coronary artery disease and several cardiovascular risk factors and suggest molecular mechanisms underlying the association between depression and increased cardiovascular disease risk.     

Stable carbon and oxygen isotopes in human tooth enamel: Identifying breastfeeding and weaning in prehistory. Am. J. Phys. Anthropol. 106: 1–18.

ERRATUM: Wright LE and Schwarcz HP (1998) Stable Carbon and Oxygen Isotopes in Human Tooth Enamel: Identifying Breastfeeding and Weaning in Prehistory. Am. J. Phys. Anthropol. 106: 1–18. Isotopic ratios were incorrectly printed as percentages (%) rather than units permil (‰). Wherever “breast feeding” and “breast fed” occur, the words should be combined into “breastfeeding” and “breastfed” respectively. The correct information on isotopic ratios is the following: p. 1, Abstract: all % signs should be “‰”; p. 2, column two, last line: “… δ¹³C values¹, have been …”; p. 2, Footnote 1 should read: “Isotope ratios of carbon and oxygen are expressed in δ notation as follows, δ = [(R_sample/R_standard) − 1] × 1000, where R = ¹³C/¹²C for δ¹³C, and R = ¹⁸O/¹⁶O for δ¹⁸O, and are in units permil, ‰.”; p. 3, column two: all % signs should be “‰”, except for the 23rd line from the bottom, which reads: “… provided 95% of water intake by all infants …”; p. 5: all % signs should be “‰”; p. 6, column one: 8th and 9th line from bottom should be “… mean deviations were 0.029‰ for δ¹³C and 0.024‰ for δ¹⁸O …”; p. 6, column one: 2nd line from bottom should be “… only 0.208‰ for δ¹³C and only 0.091‰ for δ¹⁸O …”; p. 6, column two: top line: “… of 0.5‰ in δ¹³C and 0.2‰ in δ¹⁸O …”; p. 8, 9 and 10: all % signs should be “‰”; p. 11, column two: 7th line from top: “… the lipids are 4-6‰ lighter …”; p. 12, 13 and 14: all % signs should be “‰.”     

Increased oxidative damage to DNA in a transgenic mouse model of Huntington's disease

Mitochondrial dysfunction and oxidative damage may play a role in the pathogenesis of Huntington's disease (HD). We examined concentrations of 8-hydroxy-2-deoxyguanosine (OH(8)dG), a well-established marker of oxidative damage to DNA, in a transgenic mouse model of HD (R6/2). Increased concentrations of OH(8)dG were found in the urine, plasma and striatal microdialysates of the HD mice. Increased concentrations were also observed in isolated brain DNA at 12 and 14 weeks of age. Immunocytochemistry showed increased OH(8)dG staining in late stages of the illness. These results suggest that oxidative damage may play a role in the pathogenesis of neuronal degeneration in the R6/2 transgenic mouse model of HD.     

Effects of habitat patchiness and connectivity on the spatial ecology of the root vole Microtus oeconomus

1. The effect of habitat patchiness and connectivity on dispersal distances and spatial aggregation of individuals is investigated in 12 enclosed populations of the root vole, Microtus oeconomus , employing a factorial experimental design with three different patch configurations and two distinct geographical root vole strains. The three patch configurations, all with an identical total area, were: two large patches, six small patches and six small patches connected by corridors.
2. The populations were followed for three generations (13. weeks) using live-trapping. Matrilineal relationships, time and place of birth, and weekly home ranges were established for the 1155 individuals in the study.
3. Smaller patch sizes enhanced dispersal, but most for one of the strains. The strain difference is, tentatively, explained by inbreeding avoidance which is known to differ between the strains.
4. The effect of habitat configuration on the dispersion pattern was similar for the two strains. Increased patchiness increased the aggregation of individuals. The two sexes diverged in their response, however, females being more aggregated than males.
5. The spatial pattern of matrilinearity was used as an indication of the resulting effect of habitat configuration on the demic structure in space. Patchiness enhanced and connectivity decreased the substructuring.     

Complement-mediated lysis in vitro of newly excysted tapeworms: Hymenolepis diminuta, Hymenolepis microstoma, Hymenolepis nana and Hymenolepis citelli

Bøgh H., Christensen J.P.B. and Andreassen J. 1986. Complement-mediated lysis in vitro of newly excysted tapeworms: Hymenolepis diminuta, Hymenolepis microstoma, Hymenolepis nana and Hymenolepis citelii. International Journal for Parasitology16: 157–161. Newly excysted worms of Hymenolepis diminuta were lysed in 50% normal serum from all 13 animal species tested, including man. Since H. diminuta was neither lysed in complement inactivated serum—by heat or adding EDTA, LPS or CVF—nor in C5-deficient mouse serum, it is concluded that the lysis was associated with the complement cascade. It is shown that H. diminuta can activate the complement system via both the classical and alternative pathway. Furthermore, it is indicated that the lysis is independent of serum antibodies. Hymenolepis nana and H. citelli were also lysed in all normal sera tested, eight and six respectively, while newly excysted worms of H. microstoma were lysed in normal sera from 10 mammals and birds, but not in sera from its hosts, the mouse, rat and golden hamster. This indicates that the complement system of these three species differs from that of the other species tested in such a way that H. microstoma is able to avoid lysis in these sera.     

Thermal stability,mechanical properties and reducible cross-links of rat tail tendon in experimental diabetes

Thermal stability (measured as isometric contraction force), biomechanical properties and reducible cross-links were measured in tail tendons from streptozotocin diabetic rats, with and without insulin treatment. After 10 days of diabetes the maximum thermal contraction force was unchanged, but the relaxation following the maximal contraction was retarded. After 30 days the maximum contraction force was increased and the relaxation rate was decreased. The maximum strength and stiffness of the tendons were increased after 10 days of diabetes and even more after 30 days. There was no change in the density of reducible cross-links. However, diabetes increased the amount of glucose attached to the lysine and hydroxylysine residues of collagen. Insulin treatment prevented all changes in thermal stability and mechanical properties. The results indicate that stabilization of collagen fibres in diabetes does not follow the same pattern as that seen in normal ageing.     

New Nystatin-Related Antifungal Polyene Macrolides with Altered Polyol Region Generated via Biosynthetic Engineering of Streptomyces noursei

Polyene macrolide antibiotics, including nystatin and amphotericin B, possess fungicidal activity and are being used as antifungal agents to treat both superficial and invasive fungal infections. Due to their toxicity, however, their clinical applications are relatively limited, and new-generation polyene macrolides with an improved therapeutic index are highly desirable. We subjected the polyol region of the heptaene nystatin analogue S44HP to biosynthetic engineering designed to remove and introduce hydroxyl groups in the C-9-C-10 region. This modification strategy involved inactivation of the P450 monooxygenase NysL and the dehydratase domain in module 15 (DH15) of the nystatin polyketide synthase. Subsequently, these modifications were combined with replacement of the exocyclic C-16 carboxyl with the methyl group through inactivation of the P450 monooxygenase NysN. Four new polyene macrolides with up to three chemical modifications were generated, produced at relatively high yields (up to 0.51 g/liter), purified, structurally characterized, and subjected to in vitro assays for antifungal and hemolytic activities. Introduction of a C-9 hydroxyl by DH15 inactivation also blocked NysL-catalyzed C-10 hydroxylation, and these modifications caused a drastic decrease in both antifungal and hemolytic activities of the resulting analogues. In contrast, single removal of the C-10 hydroxyl group by NysL inactivation had only a marginal effect on these activities. Results from the extended antifungal assays strongly suggested that the 9-hydroxy-10-deoxy S44HP analogues became fungistatic rather than fungicidal antibiotics.     

Hydrolytic cleavage by a group I intron ribozyme is dependent on RNA structures not important for splicing.

DiGIR2 is the group I splicing-ribozyme of the mobile twin-ribozyme intron Dir.S956-1, present in Didymium nuclear ribosomal DNA. DiGIR2 is responsible for intron excision, exon ligation, 3'-splice site hydrolysis, and full-length intron RNA circle formation. We recently reported that DiGIR2 splicing (intron excision and exon ligation) competes with hydrolysis and subsequent full-length intron circularization. Here we present experimental evidence that hydrolysis at the 3'-splice site in DiGIR2 is dependent on structural elements within the P9 subdomain not involved in splicing. Whereas the GCGA tetra-loop in P9b was found to be important in hydrolytic cleavage, probably due to tertiary RNA-RNA interactions, the P9.2 hairpin structure was found to be essential for hydrolysis. The most important positions in P9.2 include three adenosines in the terminal loop (L9.2) and a consensus kink-turn motif in the proximal stem. We suggest that the L9.2 adenosines and the kink-motif represent key regulatory elements in the splicing and hydrolytic reaction pathways.