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131.
D. Burger G. Dolivo E. Marti H. Sieme C. Wedekind 《Proceedings. Biological sciences / The Royal Society》2015,282(1807)
Odours of vertebrates often contain information about the major histocompatibility complex (MHC), and are used in kin recognition, mate choice or female investment in pregnancy. It is, however, still unclear whether MHC-linked signals can also affect male reproductive strategies. We used horses (Equus caballus) to study this question under experimental conditions. Twelve stallions were individually exposed either to an unfamiliar MHC-similar mare and then to an unfamiliar MHC-dissimilar mare, or vice versa. Each exposure lasted over a period of four weeks. Peripheral blood testosterone levels were determined weekly. Three ejaculates each were collected in the week after exposure to both mares (i.e. in the ninth week) to determine mean sperm number and sperm velocity. We found high testosterone levels when stallions were kept close to MHC-dissimilar mares and significantly lower ones when kept close to MHC-similar mares. Mean sperm number per ejaculate (but not sperm velocity) was positively correlated to mean testosterone levels and also affected by the order of presentation of mares: sperm numbers were higher if MHC-dissimilar mares were presented last than if MHC-similar mares were presented last. We conclude that MHC-linked signals influence testosterone secretion and semen characteristics, two indicators of male reproductive strategies. 相似文献
132.
Iveta M. Petrova Liza L. Lahaye Tania Martiá?ez Anja W. M. de Jong Martijn J. Malessy Joost Verhaagen Jasprina N. Noordermeer Lee G. Fradkin 《Molecular and cellular biology》2013,33(20):4116-4127
Ryk pseudokinase receptors act as important transducers of Wnt signals, particularly in the nervous system. Little is known, however, of their interactions at the cell surface. Here, we show that a Drosophila Ryk family member, DERAILED (DRL), forms cell surface homodimers and can also heterodimerize with the two other fly Ryks, DERAILED-2 and DOUGHNUT ON 2. DERAILED homodimerization levels increase significantly in the presence of its ligand, WNT5. In addition, DERAILED displays ligand-independent dimerization mediated by a motif in its transmembrane domain. Increased dimerization of DRL upon WNT5 binding or upon the replacement of DERAILED''s extracellular domain with the immunoglobulin Fc domain results in an increased recruitment of the Src family kinase SRC64B, a previously identified downstream pathway effector. Formation of the SRC64B/DERAILED complex requires SRC64B''s SH2 domain and DERAILED''s PDZ-binding motif. Mutations in DERAILED''s inactive tyrosine kinase-homologous domain also disrupt the formation of DERAILED/SRC64B complexes, indicating that its conformation is likely important in facilitating its interaction with SRC64B. Finally, we show that DERAILED''s function during embryonic axon guidance requires its Wnt-binding domain, a putative juxtamembrane extracellular tetrabasic cleavage site, and the PDZ-binding domain, indicating that DERAILED''s activation involves a complex set of events including both dimerization and proteolytic processing. 相似文献
133.
K J Rothschild Y W He S Sonar T Marti H G Khorana 《The Journal of biological chemistry》1992,267(3):1615-1622
The role of Thr-46 and Thr-89 in the bacteriorhodopsin photocycle has been investigated by Fourier transform infrared difference spectroscopy and time-resolved visible absorption spectroscopy of site-directed mutants. Substitutions of Thr-46 and Thr-89 reveal alterations in the chromophore and protein structure during the photocycle, relative to wild-type bacteriorhodopsin. The mutants T89D and to a lesser extent T89A display red shifts in the visible lambda max of the light-adapted states compared with wild type. During the photocycle, T89A exhibits an increased decay rate of the K intermediate, while a K intermediate is not detected in the photocycle of T89D at room temperature. In the carboxyl stretch region of the Fourier transform infrared difference spectra of T89D, a new band appears as early as K formation which is attributed to the deprotonation of Asp-89. Along with this band, an intensity increase occurs in the band assigned to the protonation of Asp-212. In the mutant T46V, a perturbation in the environment of Asp-96 is detected in the L and M intermediates which corresponds to a drop in its pK alpha. These data indicate that Thr-89 is located close to the chromophore, exerts steric constraints on it during all-trans to 13-cis isomerization, and is likely to participate in a hydrogen-bonding network that extends to Asp-212. In addition, a transient interaction between Thr-46 and Asp-96 occurs early in the photocycle. In order to explain these results, a previously proposed model of proton transport is extended to include the existence of a transient network of hydrogen-bonded residues. This model can account for the protonation changes of key amino acid residues during the photocycle of bacteriorhodopsin. 相似文献
134.
Effects of individual genetic substitutions of arginine residues on the deprotonation and reprotonation kinetics of the Schiff base during the bacteriorhodopsin photocycle.
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The rates are determined for the deprotonation and reprotonation of the protonated Schiff base (PSB) as well as of formation and decay of the UV transient in the photocycle of seven bacteriorhodopsin (bR) mutants in which Arg-7, 82, 164, 175, 225, or 227 are replaced by glutamine and Arg-134 by cysteine. The results show that all these mutations increase the rate of deprotonation of the PSB compared to ebR, (wild-type bacteriorhodopsin expressed in Escherichia coli) greatly increase the rate of the reprotonation of the SB (Schiff base) in the case of the Arg-164 and Arg-175 mutations and dramatically decrease this rate in the case of the Arg-227 mutation. Temperature studies on the latter mutant suggest that the observed change in its rate of reprotonation is due to large decrease in the energy and entropy of activation, similar to those observed for Asp-96 mutations (Miller, A. and D. Orsterhelt. 1990. Biochim. Biophys. Acta. 1020:57-64). These results suggest that the reprotonation process is changed to a proton diffusion-controlled mechanism in the Arg-227 mutant due to a change in the structure of the proton channel. The absorption intensity ratio (AUV/AMslow) of each arginine mutant relative to that of ebR is found to be similar to that for native purple membrane (PM) except for the Arg-227 mutant where it is greatly reduced, and for the Arg-82 mutant where it is not observed, suggesting that both Arg-227 and Arg-82 residues somehow play roles in inducing the UV transient absorption. All the above results are discussed in terms of the model for the structure of bR proposed by Henderson, R., J.M. Baldwin, T.A. Ceska, F. Zemlin, E. Beckmann, and K.H. Downing. (1990. J. Mol. Biol. 213:899-929). 相似文献
135.
Within the framework of conservation actions for the Eurasian lynx (Lynx lynx), ageing of individuals is required to assess suitability for translocation and to investigate population dynamics and disease epidemiology. We aimed to develop a standardised ageing tool for free-ranging Eurasian lynx, which would be non-invasive, time- and cost-effective, and applicable under field conditions. We used tooth pictures of 140 free-ranging lynx of known age from Switzerland. Tooth colour, calculus, number of incisor teeth and canine, premolar and molar tooth wear were recorded according to pre-defined criteria. Statistical comparisons among the categories of each criterion revealed significant differences for all criteria. Tooth colour and canine tooth morphology showed obvious and consistent alterations with age. Together with the molar tooth shape, premolar tooth tips, incisor teeth and amount of calculus, they pictured the age-related changes in lynx dentition. Crown fractures, enamel flaking and open pulp cavities were observed with an increasing prevalence over age but were also sporadically seen in juveniles. Based on the obtained results, we developed a classification scheme distinguishing six age classes: <?1 year, 1–2 years, 3–6 years, 7–9 years, 10–13 years, ≥?14 years. The scheme was subsequently tested with the same lynx. Classification success rates of different readers ranged from 69 to 88% but errors did not exceed one age class. The homogenous tooth replacement pattern observed in lynx <?1 year allowed us to develop a separate ageing chart to age juveniles in months. The proposed scheme is a promising tool to objectively assign lynx to meaningful age categories. 相似文献
136.
Noctuidonema dibolia n. sp., an ectoparasite of adults of the noctuid moth Mocis latipes (Guenée) is described. The differentiating characters are a club-shaped body with a subterminal vulva in the female, spicules with a reduced matrix and sheath and closely apposed dorsal and ventral arms in the male, very long stylet and conus, moderately prominent stylet knobs, a bluntly rounded head, and a large renette cell in both sexes. Lateral fields, rectum, anus, bursa, and gubernaculum are absent. Noctuidonema dibolia differs from the other species of the subfamily Noctuidonematinae in the size and robustness of the body, the length of the stylet and conus, the length of the tail, and the shape of the spicules. 相似文献
137.
In a previous study, we isolated genomic clones encoding core 2-1,6-N-acetylglucosaminyltransferase (C2GnT) and blood group IGnT and proposed that these two genes were produced from a common ancestral gene by duplication, diversion and intron insertion. In the present study, we have isolated a pseudogene which is highly related to the gene ofC2GnT. The sequence analysis of this pseudogene indicated that the pseudogene was produced by duplication of a common precursor gene forC2GnT. These results taken together strongly suggest that the ancestral gene was first duplicated and one of the duplicated genes directly evolved into theIGnT gene. The other duplicated gene was further duplicated to produce theC2GnT gene and the pseudogene. 相似文献
138.
Tatsuo Hase Marti Jett Edward Asafo-Adjei Michael Topper 《In vitro cellular & developmental biology. Animal》1996,32(6):322-328
Summary The release of chromaffin granular content from staphylococcal enterotoxin B (SEB)-treated and-untreated PC12 cells was studied
by electron microscopy. The treatment of the cells with SEB at the concentration of 20 μg/ml caused marked increase of the
chromaffin granules that either bound to the plasma membrane by the characteristic rods, measuring 15 to 20 nm in length and
showing a tubular structure, or budded off at the free cell surface, surrounded by a layer of rod-containing cytoplasm and
enclosed by the plasma membrane. The binding between the granular and plasma membranes by the rods did not lead to membrane
fusion and exocytosis of the granular content. Many of the bound granules showed vesiculation with loss of the electron-dense
core material; at the same time, some of the binding rods contained intraluminal electron-dense material similar to the granular
core material. These findings suggested that the electron-dense material (i.e., norepinephrine) of the bound granules was
released extracellularly through channels within the rods. Although the granules were bound to the plasma membrane with equal
frequency at the free and contiguous cell surfaces, the granular budding occurred only at the free cell surface, indicating
that it occurred incidentally to some granules bound at the free cell surfaces. On the basis of the morphological observations,
it is postulated that the electron-dense material of the bound granule is selectively released extracellularly through the
rods, leaving the vesiculated granules behind in the cytoplasm. The same mode of release of the granular content was observed,
though less frequently, in the untreated control cells. No morphological evidence that indicated that the granular content
was released extracellularly by exocytosis was found in the treated and control cells. The present observations indicated
that the SEB treatment of PC12 cells stimulated the binding of chromaffin granules to the plasma membrane by the rods and
the budding of the bound granules at the free cell surface. 相似文献
139.
Gladys Vidal Estrella Aspé M. Cristina Marti Marlene Roeckel 《Biotechnology letters》1997,19(2):117-122
Fishmeal industries processes produce effluents with high load organic matter. These effluents, after recycling and physical-chemical pretreatment, have a high organic content (5-6 g COD/l), proteins (3-5 g/l), salinity close to sea water, sodium chloride (30 g/l) and sulphate (1-3.3 g/l). An anaerobic filter was used for the treatment of this wastewater, with marine sediment as anaerobic inoculum. Anaerobic filter removed up to 70% of the influent COD concentrations at organic loading rates (OLR) of 9.5 and 14.3 (g/l d) and sulphate up to 80% at OLR of 7.1 and 14.3 (g/l d) whereas the pH ranged between 7.0 and 7.5. These results show that anaerobic filter systems are applicable to recycled wastewaters from fishmeal. 相似文献
140.
Siddha Kasar Chingiz Underbayev Moinuddin Hassan Ilko Ilev Heba Degheidy Steven Bauer Gerald Marti Carol Lutz Elizabeth Raveche Mona Batish 《PloS one》2016,11(3)
New Zealand Black (NZB) mice, a de novo model of CLL, share multiple characteristics with CLL patients, including decreased expression of miR-15a/16-1. We previously discovered a point mutation and deletion in the 3'' flanking region of mir-16-1 of NZB and a similar mutation has been found in a small number of CLL patients. However, it was unknown whether the mutation is the cause for the reduced miR-15a/16-1 expression and CLL development. Using PCR and in vitro microRNA processing assays, we found that the NZB sequence alterations in the mir-15a/16-1 loci result in deficient processing of the precursor forms of miR-15a/16-1, in particular, we observe impaired conversion of pri-miR-15a/16-1 to pre-miR-15a/16-1. The in vitro data was further supported by derivation of congenic strains with replaced mir-15a/16-1 loci at one or both alleles: NZB congenic mice (NmiR+/-) and DBA congenic mice (DmiR-/-). The level of miR-15a/16-1 reflected the configuration of the mir-15a/16-1 loci with DBA congenic mice (DmiR-/-) showing reduced miR-15a levels compared to homozygous wild-type allele, while the NZB congenic mice (NmiR+/-) showed an increase in miR-15a levels relative to homozygous mutant allele. Similar to Monoclonal B-cell Lymphocytosis (MBL), the precursor stage of the human disease, an overall expansion of the B-1 population was observed in DBA congenic mice (DmiR-/-) relative to wild-type (DmiR+/+). These studies support our hypothesis that the mutations in the mir-15a/16-1 loci are responsible for decreased expression of this regulatory microRNA leading to B-1 expansion and CLL development. 相似文献