Paternal genetic effects on offspring fitness are context dependent within the extrapair mating system of a socially monogamous passerine

Avian extrapair mating systems provide an interesting model to assess the role of genetic benefits in the evolution of female multiple mating behavior, as potentially confounding nongenetic benefits of extrapair mate choice are seen to be of minor importance. Genetic benefit models of extrapair mating behavior predict that females engage in extrapair copulations with males of higher genetic quality compared to their social mates, thereby improving offspring reproductive value. The most straightforward test of such good genes models of extrapair mating implies pairwise comparisons of maternal half-siblings raised in the same environment, which permits direct assessment of paternal genetic effects on offspring traits. But genetic benefits of mate choice may be difficult to detect. Furthermore, the extent of genetic benefits (in terms of increased offspring viability or fecundity) may depend on the environmental context such that the proposed differences between extrapair offspring (EPO) and within-pair offspring (WPO) only appear under comparatively poor environmental conditions. We tested the hypothesis that genetic benefits of female extrapair mate choice are context dependent by analyzing offspring fitness-related traits in the coal tit (Parus ater) in relation to seasonal variation in environmental conditions. Paternal genetic effects on offspring fitness were context dependent, as shown by a significant interaction effect of differential paternal genetic contribution and offspring hatching date. EPO showed a higher local recruitment probability than their maternal half-siblings if born comparatively late in the season (i.e., when overall performance had significantly declined), while WPO performed better early in the season. The same general pattern of context dependence was evident when using the number of grandchildren born to a cuckolding female via her female WPO or EPO progeny as the respective fitness measure. However, we were unable to demonstrate that cuckolding females obtained a general genetic fitness benefit from extrapair fertilizations in terms of offspring viability or fecundity. Thus, another type of benefit could be responsible for maintaining female extrapair mating preferences in the study population. Our results suggest that more than a single selective pressure may have shaped the evolution of female extrapair mating behavior in socially monogamous passerines.     

华西银腊梅挥发油化学成分的研究

用水蒸气蒸馏法提取华西银腊梅挥发油,并用气相色谱-质谱(GC-MS)联用技术对其挥发油的化学成分进行分析,结果共鉴定了其中的39种成分,所鉴定成分含量约占总检出量的87.83%。其化学成分主要为(Z,Z)-9,12-十八碳二烯酸甲酯(9.00%),壬醛(5.83%),二十一烷(5.69%),二十烷(5.08%),辛炔酸(4.50%),2,6,10,15-四甲基十七烷(3.93%),(Z)-6-十八烯酸甲酯(3.65%),3,8-二甲基十一烷(3.52%),1-十六碳炔(3.31%),肉豆蔻酸(2.86%),月桂醛(2.81%),壬酸(2.23%),5,6,7,7α-四氢-4,4,7α三甲基-2(4H)-苯并呋喃酮(2.18%)等。     

Lysis of bacterioids in the vicinity of the host cell nucleus in an ineffective (fix-) root nodule of soybean (Glycine max)

In nodules of Glycine max cv. Mandarin infected with a nod ⁺fix^- mutant of Rhizobium japonicum (RH 31-Marburg), lysis of bacteroids was observed 20 d after infection, but occurred in the region around the host cell nucleus, where lytic compartments were formed. Bacteroids, and peribacteroid membranes in other parts of the host cell remained stable until senescence (40d after infection). With two other nod⁺ fix^- mutants of R. japonicum either stable bacteroids and peribacteroid membranes were observed throughout the cell (strain 61-A-165) or a rapid degeneration of bacteroids without an apparent lysis (strain USDA 24) occurred. The size distribution of RH 31-Marburg-infected nodules exhibited only two maxima compared with four in wild-type nodules and nodule leghaemoglobin content was found to be reduced to about one half that of the wild type. The RH 31-Marburg-nodule type is discussed in relation to the stability of the bacteroids and the peribacteroid membrane system in soybean.     

Evolution of budding yeast prion-determinant sequences across diverse fungi

Prions are transmissible self-replicating alternative states of proteins. Four prions ([PSI+], [URE3], [RNQ+] and [NU+]) can be inherited cytoplasmically in Saccharomyces cerevisiae laboratory strains. In the case of [PSI+], there is increasing evidence that prion formation may engender mechanisms to uncover hidden genetic variation. Here, we have analysed the evolution of the prion-determinant (PD) domains across 21 fungi, focusing on compositional biases, repeats and substitution rates. We find evidence for constraint on all four PD domains, but each domain has its own evolutionary dynamics. For [PSI+], the Q/N bias is maintained in fungal clades that diverged one billion years ago, with purifying selection observed within the Saccharomyces species. The degree of Q/N bias is correlated with the degree of local homology to prion-associated repeats, which occur rarely in other proteins (<1% of sequences for the proteomes studied). The evolutionary conservation of Q/N bias in Sup35p is unusual, with only eight other S. cerevisiae proteins showing similar, phylogenetically deep patterns of bias conservation. The [URE3] PD domain is unique to Hemiascomycota; part of the PD domain shows purifying selection, whereas another part engenders bias changes between clades. Also, like for Sup35p, the [RNQ+] and [NU+] PD domains show purifying selection in Saccharomyces species. Additionally, in each proteome, we observe on average several hundred yeast-prion-like domains, with fewest in fission yeast. Our findings on yeast prion evolution provide further support for the functional significance of these molecules.     

Effects of long-term selenium yeast supplementation on selenium status studied in the rat

To investigate the selenium status during long-term dietary supply of selenium yeast, 30-day-old male rats were fed for 379 days a methionine-adequate low-selenium diet supplemented with 0.2 mg Se/kg (selenium-adequate diet) or 1.5 mg Se/kg (high-selenium diet) in the form of selenium yeast that contained 60% of the element as l-selenomethionine. Their selenium load was determined at several intervals by neutron activation analysis of the selenium concentrations in the main selenium body pools, skeletal muscle and liver. After 64 days the tissue selenium concentrations plateaued in both groups and then stayed at that level. Compared with the selenium-adequate group, elevated tissue selenium concentrations were found in the high-selenium group, but the increase by a factor of 3.5 in the muscle and by a factor of 2.3 in the liver was smaller than the 7.5-fold increase in the selenium intake. In the selenium-adequate group about 50% of the muscle selenium and 30% of the liver selenium and in the high-selenium group about 85% of the muscle selenium and 70% of the liver selenium were estimated to be present in non-selenoprotein forms. During selenium depletion the liver glutathione peroxidase activity in the high-selenium group remained unaffected for 4 weeks and then decreased more slowly than that in the selenium-adequate group. From these results it can be concluded that selenium incorporated from the selenium yeast diet into non-selenoprotein forms can serve as an endogenous selenium source to maintain selenoprotein levels in periods of insufficient selenium supply.     

Complementarity of particles and pits in freeze-fractured hepatic and cardiac gap junctions

Summary Particles and pits of freeze-fractured gap junctions are considered as complementary structures despite the frequent observations of more regular and closer spacings of pits, ascribed to plastic deformation of particle arrays. Recently, however, the noncomplementarity of pits and particles in Purkinje fibers has been reported. To ascertain the relationship between both structures, gap junctions from fixed, cryoprotected liver and myocardium were investigated using spacing and density measurements and complementary replicas.In hepatocyte gap junctions, the center-to-center distances (mean±sd) among pits, 9.57±1.49 nm, and particles, 9.70±1.77 nm, are not significantly different. Density determinations yielded a slightly higher value for the pits, (11,510±830)/m², than for the particles, (11,230±950)/m². In the myocardium, the spacing of the regularly arrayed pits, 9.55±1.33 nm barely exceeds the value of 9.44±1.62 nm for the particles, which show some clustering. However, the packing density for the pits, (10,090±740)/m², appears a little higher than that of the particles (9,890±920)/m². As density and spacing measurements provided no decisive answers, the positions of individual pits and particles of complementary junctional faces were recorded on transparent sheets and compared. In this fashion, a one-to-one correspondence between particles and pits could be established, while small discrepancies may be attributed to plastic deformation. Moreover, the collinearity of pits and particles may be suggested by the observation of a platinum grain in the center of many pits.     

Sphingolipid long-chain base hydroxylation is important for growth and regulation of sphingolipid content and composition in Arabidopsis

Sphingolipids are structural components of endomembranes and function through their metabolites as bioactive regulators of cellular processes such as programmed cell death. A characteristic feature of plant sphingolipids is their high content of trihydroxy long-chain bases (LCBs) that are produced by the LCB C-4 hydroxylase. To determine the functional significance of trihydroxy LCBs in plants, T-DNA double mutants and RNA interference suppression lines were generated for the two Arabidopsis thaliana LCB C-4 hydroxylase genes Sphingoid Base Hydroxylase1 (SBH1) and SBH2. These plants displayed reductions in growth that were dependent on the content of trihydroxy LCBs in sphingolipids. Double sbh1 sbh2 mutants, which completely lacked trihydroxy LCBs, were severely dwarfed, did not progress from vegetative to reproductive growth, and had enhanced expression of programmed cell death associated-genes. Furthermore, the total content of sphingolipids on a dry weight basis increased as the relative amounts of trihydroxy LCBs decreased. In trihydroxy LCB-null mutants, sphingolipid content was approximately 2.5-fold higher than that in wild-type plants. Increases in sphingolipid content resulted from the accumulation of molecular species with C16 fatty acids rather than with very-long-chain fatty acids, which are more commonly enriched in plant sphingolipids, and were accompanied by decreases in amounts of C16-containing species of chloroplast lipids. Overall, these results indicate that trihydroxy LCB synthesis plays a central role in maintaining growth and mediating the total content and fatty acid composition of sphingolipids in plants.     

Primary malignant non-Hodgkin's lymphoma of the breast: a study of seven cases and literature review

ABSTRACT: INTRODUCTION: Primary breast lymphoma is an uncommon disease with poor clinical outcome. Breast lymphomas present less than 0.5% of malignant breast neoplasms and 2.2% of extranodal lymphomas. This study investigated the clinicopathological features and optimal treatment of PBL. Case presentations Clinical records of seven Moroccan PBL patients, treated at the National Institute of Oncology, Rabat, Morocco, from 2002 to 2010, were reviewed. Six of the patients were women and one a man, with ages ranging from 32 to 76. Five patients had stage IE and two stage IIE. All of the patients were classified with DLBCL. Of seven patients, one received a mastectomy and three excision of the breast lesion. Axillary dissection was performed in three patients. Two patients received chemotherapy followed by radiotherapy, while four received chemotherapy alone. Complete remission (CR) following primary treatment for all patients with PBL except in two cases was obtained. In one patient, recurrence occurred. CONCLUSIONS: There is no consensus on the question of how to best treat PBL: Mastectomy offers no benefit in the treatment of PBL. The combined therapy approach, with chemotherapy and radiotherapy, is the most successful treatment. PBL is poorly represented in rituximab-containing trials in DLBCL patients; there is not much experience with this agent in breast DLBCL. Because of the high incidence of central nervous system (CNS) involvement in PBL patients, many authors strongly believe that patients with aggressive forms of PBL should receive CNS infiltration prophylaxis.     

A mutational analysis of U12-dependent splice site dinucleotides

Introns spliced by the U12-dependent minor spliceosome are divided into two classes based on their splice site dinucleotides. The /AU-AC/ class accounts for about one-third of U12-dependent introns in humans, while the /GU-AG/ class accounts for the other two-thirds. We have investigated the in vivo and in vitro splicing phenotypes of mutations in these dinucleotide sequences. A 5' A residue can splice to any 3' residue, although C is preferred. A 5' G residue can splice to 3' G or U residues with a preference for G. Little or no splicing was observed to 3' A or C residues. A 5' U or C residue is highly deleterious for U12-dependent splicing, although some combinations, notably 5' U to 3' U produced detectable spliced products. The dependence of 3' splice site activity on the identity of the 5' residue provides evidence for communication between the first and last nucleotides of the intron. Most mutants in the second position of the 5' splice site and the next to last position of the 3' splice site were defective for splicing. Double mutants of these residues showed no evidence of communication between these nucleotides. Varying the distance between the branch site and the 3' splice site dinucleotide in the /GU-AG/ class showed that a somewhat larger range of distances was functional than for the /AU-AC/ class. The optimum branch site to 3' splice site distance of 11-12 nucleotides appears to be the same for both classes.