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121.
Plath M Hauswaldt JS Moll K Tobler M García De León FJ Schlupp I Tiedemann R 《Molecular ecology》2007,16(5):967-976
We investigated genetic differentiation and migration patterns in a small livebearing fish, Poecilia mexicana, inhabiting a sulfidic Mexican limestone cave (Cueva del Azufre). We examined fish from three different cave chambers, the sulfidic surface creek draining the cave (El Azufre) and a nearby surface creek without the toxic hydrogen sulphide (Arroyo Cristal). Using microsatellite analysis of 10 unlinked loci, we found pronounced genetic differentiation among the three major habitats: Arroyo Cristal, El Azufre and the cave. Genetic differentiation was also found within the cave between different pools. An estimation of first-generation migrants suggests that (i) migration is unidirectional, out of the cave, and (ii) migration among different cave chambers occurs to some extent. We investigated if the pattern of genetic differentiation is also reflected in a morphological trait, eye size. Relatively large eyes were found in surface habitats, small eyes in the anterior cave chambers, and the smallest eyes were detected in the innermost cave chamber (XIII). This pattern shows some congruence with a previously proposed morphocline in eye size. However, our data do not support the proposed mechanism for this morphocline, namely that it would be maintained by migration from both directions into the middle cave chambers. This would have led to an increased variance in eye size in the middle cave chambers, which we did not find. Restricted gene flow between the cave and the surface can be explained by local adaptations to extreme environmental conditions, namely H2S and absence of light. Within the cave system, habitat properties are patchy, and genetic differentiation between cave chambers despite migration could indicate local adaptation at an even smaller scale. 相似文献
122.
Moll SJ Jones CJ Crocker IP Baker PN Heazell AE 《Apoptosis : an international journal on programmed cell death》2007,12(9):1611-1622
Pre-eclampsia and intrauterine growth restriction are associated with increased apoptosis of placental villous trophoblast.
This may result from placental hypoperfusion, leading to the generation of reactive oxygen species (ROS). Apoptosis can be
induced in villous trophoblast following exposure to oxidative stress. Epidermal growth factor (EGF) reduces trophoblast apoptosis
resulting from exposure to hypoxia. We hypothesised that exposure to hydrogen peroxide, a potent generator of ROS, would induce
apoptosis in term placental villous explants and that this could be reduced by treatment with EGF. Placental explants were
taken from normal term pregnancies and exposed to increasing doses of hydrogen peroxide (0–1,000 μM) or to a combination of
increasing doses of hydrogen peroxide and EGF (0–100 ng/ml) for either 6 or 48 h. Apoptosis was assessed by TUNEL, proliferation
by Ki-67 immunostaining, necrosis by lactate dehydrogenase activity and trophoblast differentiation by human chorionic gonadotrophin
(hCG) secretion in conditioned culture media. Immunoperoxidase staining was performed to identify phosphorylated-AKT (p-AKT)
and phosphorylated-PI3 kinase (p-PI3k). Exposure to 1,000 μM hydrogen peroxide for 48 h induced apoptosis in placental explants.
The increase in TUNEL positive nuclei predominantly localised to syncytiotrophoblast. The amount of apoptosis was reduced
to control levels by treatment with 10 and 100 ng/ml EGF. Proliferation of cytotrophoblasts within villous explants was significantly
reduced following exposure to 1,000 μM hydrogen peroxide, this was restored to control levels by simultaneous treatment with
10 or 100 ng/ml EGF. Neither exposure to hydrogen peroxide or EGF altered the amount of necrosis. There was increased immunostaining
for pPI3K following treatment with EGF. This study shows that apoptosis may be induced in villous trophoblast following exposure
to ROS, and demonstrates the anti-apoptotic effect of EGF in trophoblast, the maintenance of which is essential for normal
pregnancy. 相似文献
123.
124.
MAXIMO GACULA JR. SHERI RUTENBECK LANA POLLACK ANNA V.A. RESURRECCION HOWARD R. MOSKOWITZ 《Journal of sensory studies》2007,22(2):194-211
This study assessed the meaning of just‐about‐right (JAR) categories when used with a 5‐point intensity scale. The panelists comprised both consumer and in‐house respondents. The JAR categories have various meanings as perceived by the respondents: “prefer product,”“very good,”“I like the product,”“like it very much,”“highly favorable,”“high acceptability,”“desirable like the product,”“best for the situation” and “correct.” Thus, the JAR meanings invoke preference and acceptability. This article presents two additional analyses to help the product tested. One method of analysis divides below‐JAR deviation from the above‐JAR deviation, with standard statistical procedures applied in each data set. The second method introduces the signal‐to‐noise ratio statistic for analyzing the relation of JAR to overall liking. Both analytic methods provide new ways to look at the JAR data, especially with respect to hedonics and product improvement. 相似文献
125.
Background
Genetic systems involving multiple X chromosomes have arisen repeatedly in sexually reproducing animals. Tiger beetles (Cicindelidae) exhibit a phylogenetically ancient multiple-X system typically consisting of 2–4 X chromosomes and a single Y. Because recombination rates are suppressed in sex chromosomes, changes in their numbers and movement of genes between sex chromosomes and autosomes, could have important consequences for gene evolution and rates of speciation induced by these rearrangements. However, it remains unclear how frequent these rearrangements are and which genes are affected. 相似文献126.
127.
Konstantin Byrgazov Irina Grishkovskaya Stefan Arenz Nicolas Coudevylle Hannes Temmel Daniel N. Wilson Kristina Djinovic-Carugo Isabella Moll 《Nucleic acids research》2015,43(1):661-673
In Gram-negative bacteria, the multi-domain protein S1 is essential for translation initiation, as it recruits the mRNA and facilitates its localization in the decoding centre. In sharp contrast to its functional importance, S1 is still lacking from the high-resolution structures available for Escherichia coli and Thermus thermophilus ribosomes and thus the molecular mechanism governing the S1–ribosome interaction has still remained elusive. Here, we present the structure of the N-terminal S1 domain D1 when bound to the ribosome at atomic resolution by using a combination of NMR, X-ray crystallography and cryo-electron microscopy. Together with biochemical assays, the structure reveals that S1 is anchored to the ribosome primarily via a stabilizing π-stacking interaction within the short but conserved N-terminal segment that is flexibly connected to domain D1. This interaction is further stabilized by salt bridges involving the zinc binding pocket of protein S2. Overall, this work provides one hitherto enigmatic piece in the ′ribosome puzzle′, namely the detailed molecular insight into the topology of the S1–ribosome interface. Moreover, our data suggest novel mechanisms that have the potential to modulate protein synthesis in response to environmental cues by changing the affinity of S1 for the ribosome. 相似文献
128.
Mollá-Morales A Sarmiento-Mañús R Robles P Quesada V Pérez-Pérez JM González-Bayón R Hannah MA Willmitzer L Ponce MR Micol JL 《The Plant journal : for cell and molecular biology》2011,65(3):335-345
Arabidopsis thaliana reticulate mutants exhibit differential pigmentation of the veinal and interveinal leaf regions, a visible phenotype that often indicates impaired mesophyll development. We performed a metabolomic analysis of one ven6 (venosa6) and three ven3 reticulate mutants that revealed altered levels of arginine precursors, namely increased ornithine and reduced citrulline levels. In addition, the mutants were more sensitive than the wild-type to exogenous ornithine, and leaf reticulation and mesophyll defects of these mutants were completely rescued by exogenous citrulline. Taken together, these results indicate that ven3 and ven6 mutants experience a blockage of the conversion of ornithine into citrulline in the arginine pathway. Consistent with the participation of VEN3 and VEN6 in the same pathway, the morphological phenotype of ven3 ven6 double mutants was synergistic. Map-based cloning showed that the VEN3 and VEN6 genes encode subunits of Arabidopsis carbamoyl phosphate synthetase (CPS), which is assumed to be required for the conversion of ornithine into citrulline in arginine biosynthesis. Heterologous expression of the Arabidopsis VEN3 and VEN6 genes in a CPS-deficient Escherichia coli strain fully restored bacterial growth in minimal medium, demonstrating the enzymatic activity of the VEN3 and VEN6 proteins, and indicating a conserved role for CPS in these distinct and distant species. Detailed study of the reticulate leaf phenotype in the ven3 and ven6 mutants revealed that mesophyll development is highly sensitive to impaired arginine biosynthesis. 相似文献
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130.