Reduced habitat quality increases intrinsic but not ecological costs of reproduction

Although the costs of reproduction are predicted to vary with the quality of the breeding habitat thereby affecting population dynamics and life‐history trade‐offs, empirical evidence for this pattern remains sparse and equivocal. Costs of reproduction can operate through immediate ecological mechanisms or through delayed intrinsic mechanisms. Ignoring these separate pathways might hinder the identification of costs and the understanding of their consequences. We experimentally investigated the survival costs of reproduction for adult little owls (Athene noctua) within a gradient of habitat quality. We supplemented food to nestlings, thereby relieving the parents’ effort for brood provisioning. We used radio‐tracking and Bayesian multistate modeling based on marked recapture and dead recovery to estimate survival rates of adult little owls across the year as a function of food supplementation and habitat characteristics. Food supplementation to nestlings during the breeding season increased parental survival not only during the breeding season but also during the rest of the year. Thus, the low survival of parents of unfed broods likely represents both, strong ecological and strong intrinsic costs of reproduction. However, while immediate ecological costs occurred also in high‐quality habitats, intrinsic costs carrying over to the post‐breeding period occurred only in low‐quality habitats. Our results suggest that immediate costs resulting from ecological mechanisms such as predation, are high also in territories of high habitat quality. Long‐term costs resulting from intrinsic trade‐offs, however, are only paid in low‐quality habitats. Consequently, differential effects of habitat quality on immediate ecological and delayed intrinsic mechanisms can mask the increase of costs of reproduction in low‐quality breeding habitats. Intrinsic costs may represent an underrated mechanism of habitat quality affecting adult survival rate thereby considerably accelerating population decline in degrading habitats. This study therefore highlights the need for a long‐term perspective to fully assess the costs of reproduction and the role of habitat quality in modifying these costs.     

正常大鼠植入高血压大鼠肾脏后动脉血压的变化

本实验对12周龄的自发性高血压大鼠(spontaneouslyhypertensiverat,SHR)及其对照组WistarKyoto(WKY)大鼠进行了肾脏移植的研究,并观察受肾移植大鼠动脉血压的变化以及免疫抑制剂对动脉血压的影响。用尾套法对接受同窝另一同胞WKY大鼠肾脏移植且存活5周的6只WKY大鼠(A组)及接受SHR肾脏移植且存活5周的6只WKY大鼠(B组)的尾动脉收缩压进行检测,移植前A、B两组受肾移植大鼠的尾动脉收缩压分别为180±093和183±068kPa,无统计学显著差异(P>005);移植后3、4、5周时,B组大鼠的尾动脉收缩压显著高于A组大鼠,移植后5周时,A,B两组大鼠的收缩压分别为190±071和230±069kPa(P<0001);所用剂量的免疫抑制剂CsA对双侧肾脏完整以及右侧肾脏切除的SHR、WKY大鼠的动脉血压无显著影响。以上结果表明,SHR的肾脏在高血压的形成中可能起重要作用     

Barotolerance is inducible by preincubation under hydrostatic pressure, cold-, osmotic- and acid-stress conditions in Lactobacillus sanfranciscensis DSM 20451T

AIMS: This study addresses the inducibility of barotolerance by preincubation of Lactobacillus sanfranciscensis DSM 20451T under various sublethal stress conditions. METHODS AND RESULTS: Stress conditions which reduce the growth rate of L. sanfranciscensis DSM 20451T to 10% of its maximum were determined. These conditions were met at 43, 12.5 degrees C, a pH value of 3.7, 1.9% NaCl, or 80 MPa respectively. In contrast to heat preincubation, other prestresses, including salt, cold and pressure led to an increase of barotolerance by hydrostatic pressure of 300 MPa for 30 min. Stationary-phase cells also showed an increased barotolerance. Sublethal pressure leads to enhanced heat tolerance. CONCLUSIONS: Stress response to salt, low temperature and acidic pH as well as starvation overlap with that one to high pressure by inducing barotolerance. SIGNIFICANCE AND IMPACT OF THE STUDY: Inactivation of bacteria by high pressure treatment is influenced by their history which modulates barotolerance. Mechanisms of barotolerance appear different from heat shock defence.     

Dipolar assisted rotational resonance NMR of tryptophan and tyrosine in rhodopsin

Two dimensional (2D) solid-state (13)C.(13)C dipolar recoupling experiments are performed on a series of model compounds and on the visual pigment rhodopsin to establish the most effective method for long range distance measurements in reconstituted membrane proteins. The effects of uniform labeling, inhomogeneous B(1) fields, relaxation and dipolar truncation on cross peak intensity are investigated through NMR measurements of simple amino acid and peptide model compounds. We first show that dipolar assisted rotational resonance (DARR) is more effective than RFDR in recoupling long-range dipolar interactions in these model systems. We then use DARR to establish (13)C-(13)C correlations in rhodopsin. In rhodopsin containing 4'-(13)C-Tyr and 8,19-(13)C retinal, we observe two distinct tyrosine-to-retinal correlations in the DARR spectrum. The most intense cross peak arises from a correlation between Tyr268 and the retinal 19-(13)CH(3), which are 4.8 A apart in the rhodopsin crystal structure. A second cross peak arises from a correlation between Tyr191 and the retinal 19-(13)CH(3), which are 5.5 A apart in the crystal structure. These data demonstrate that long range (13)C em leader (13)C correlations can be obtained in non-crystalline integral membrane proteins reconstituted into lipid membranes containing less than 150 nmoles of protein. In rhodopsin containing 2-(13)C Gly121 and U-(13)C Trp265, we do not observe a Trp-Gly cross peak in the DARR spectrum despite their close proximity (3.6 A) in the crystal structure. Based on model compounds, the absence of a (13)C em leader (13)C cross peak is due to loss of intensity in the diagonal Trp resonances rather than to dipolar truncation.     

Over-expression of the testis-specific gene TSGA10 in cancers and its immunogenicity

The TSGA10 gene was originally isolated in normal testis by differential mRNA display. TSGA10 is located on chromosome 2q11.2 and consists of 19 exons extending over 3 kb. TSGA10 mRNA expression was investigated in normal and malignant tissues using quantitative real-time RT-PCR. It was predominantly expressed in the testis in adult normal tissues. In malignant tissues, TSGA10 was over-expressed in 4 of 20 hepatocellular carcinomas (HCC), 1 of 20 colon cancers, 7 of 20 ovarian cancers, 3 of 20 prostate cancers, 1 of 21 malignant melanomas, and 8 of 21 bladder cancers. Serological analysis revealed that 3 out of 346 patients with various types of cancer possessed antibody against recombinant TSGA10 protein. They included 2 patients with hepatocellular carcinoma and a patient with malignant melanoma.     

Exact log-rank tests for unequal follow-up

The asymptotic log-rank and generalized Wilcoxon tests are the standard procedures for comparing samples of possibly censored survival times. For comparison of samples of very different sizes, an exact test is available that is based on a complete permutation of log-rank or Wilcoxon scores. While the asymptotic tests do not keep their nominal sizes if sample sizes differ substantially, the exact complete permutation test requires equal follow-up of the samples. Therefore, we have developed and present two new exact tests also suitable for unequal follow-up. The first of these is an exact analogue of the asymptotic log-rank test and conditions on observed risk sets, whereas the second approach permutes survival times while conditioning on the realized follow-up in each group. In an empirical study, we compare the new procedures with the asymptotic log-rank test, the exact complete permutation test, and an earlier proposed approach that equalizes the follow-up distributions using artificial censoring. Results confirm highly satisfactory performance of the exact procedure conditioning on realized follow-up, particularly in case of unequal follow-up. The advantage of this test over other options of analysis is finally exemplified in the analysis of a breast cancer study.     

The effect of fructan on membrane lipid organization and dynamics in the dry state

Fructans are a group of fructose-based oligo- and polysaccharides, which appear to be involved in membrane preservation during dehydration by interacting with the membrane lipids. To get further understanding of the protective mechanism, the consequences of the fructan-membrane lipid interaction for the molecular organization and dynamics in the dry state were studied. POPC and DMPC were investigated in the dry state by (2)H, (31)P NMR, and Fourier transform infrared spectroscopy using two types of fructan and dextran. The order-disorder transition temperature of dry POPC was reduced by 70 degrees C in the presence of fructan. Fructan increased the mobility of the acyl chains, but immobilized the lipid headgroup region. Most likely, fructans insert between the headgroups of lipids, thereby spacing the acyl chains. This results in a much lower phase transition temperature. The headgroup is immobilized by the interaction with fructan. The location of the interaction with the lipid headgroup is different for the inulin-type fructan compared to the levan-type fructan, since inulin shows interaction with the lipid phosphate group, whereas levan does not. Dextran did not influence the phase transition temperature of dry POPC showing that reduction of this temperature is not a general property of polysaccharides.     

Vibrating membrane filtration for recovery and concentration of insect killing nematodes

New experimental data are reported that demonstrate the use of a novel vibrating membrane filter (VMF) for the combined recovery and concentration of two species of nematodes, S. feltiae and P. hermaphrodita, from mature liquid fermentation cultures. The disk membrane module had a working surface area of 0.2 m(2) and was operated at a constant flow rate of 0.2 m(3) h(-1). The recovery of the viable nematodes from the spent media and nonviable nematodes was assisted by an independently imposed oscillatory motion of the disk assembly, which produced an intense shear field at the membrane surface with calculated mean values on the order of 10(4) s(-1). Adult (nonviable) nematodes in the fermentation culture were preferentially dissolved in a detergent (sodium dodecylsulfate) and successfully separated from the juveniles using the VMF equipment. Permeate fluxes on the order of 15 to 30 L/m(2/)h were achieved for an operating transmembrane pressure of 800 mbar. Industrial-scale liquid fermentation for the manufacture of nematodes as biopesticides produces the viable nematode life stages in low-concentration suspension containing large quantities of spent media and other waste material. The VMF equipment provided a flexible operation for separation, cleaning, and concentration of viable nematodes from the fermentation broths.     

Immunospecific protein of 34.5 kDa from DNA-protein cross-links induced by cis- and trans-diamminedichloroplatinum

Cis-diamminedichloroplatinum(II) (cis-DDP) is one of the most often used anticancer drugs. It is generally accepted that the antitumor activity of the drug results from its interactions with DNA. Trans-diamminedichloroplatinum(II) (trans-DDP) also binds to DNA effectively, but is clinically ineffective. In the present work the lymphocyte nuclear proteins that participate in DNA-protein cross-links induced by cis- and trans-DDP are investigated. In lymphocytes which are incubated without platinum compounds there are DNA-binding proteins in the range of 45-71 kDa. It is shown that additional proteins of 28, 30, 34.5, 45 and 120 kDa are cross-linked with DNA in lymphocytes after 2-h incubation with cis-DDP at concentrations of 0.1 and 0.5 mM. Trans-DDP does not bind additional proteins to DNA after the same incubation time. Electrophoretic analysis shows that trans-DDP binds much more of the same nuclear proteins to DNA than cis-DDP after 12-h incubation. In this study a test for the identification of 34.5 kDa protein is also undertaken. This protein appears in the samples obtained after 12-h incubation of lymphocytes with cis- and trans-DDP at 0.5 and 1 mM, especially. The protein of 34.5 kDa from cross-links induced by 1 mM trans-DDP is recognized by antibodies against the protein of the same molecular weight from the nuclear matrix of the lymphocytes. The results obtained here are discussed in relation to the biological activity of diamminedichloroplatinum isomers.