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201.
Factors controlling brown trout Salmo trutta recruitment in Mediterranean areas are largely unknown, despite the relevance this may have for fisheries management. The
effect of hydrological variability on survival of young brown trout was studied during seven consecutive years in five resident
populations from the southern range of the species distribution. Recruit density at the end of summer varied markedly among
year-classes and rivers during the study period. Previous work showed that egg density the previous fall did not account for
more than 50% of the observed variation in recruitment density. Thus, we expected that climatic patterns, as determinants
of discharge and water temperature, would play a role in the control of young trout abundance. We tested this by analyzing
the effects of flow variation and predictability on young trout survival during the spawning to emergence and the summer drought
periods. Both hatching and emergence times and length of hatching and emergence periods were similar between years within
each river but varied considerably among populations, due to differences in water temperature. Interannual variation in flow
attributes during spawning to emergence and summer drought affected juvenile survival in all populations, once the effect
of endogenous factors was removed. Survival rate was significantly related to the timing, magnitude and duration of extreme
water conditions, and to the rate of change in discharge during hatching and emergence times in most rivers. The magnitude
and duration of low flows during summer drought appeared to be a critical factor for survival of young trout. Our findings
suggest that density-independent factors, i.e., hydrological variability, play a central role in the population dynamics of
brown trout in populations from low-latitude range margins. Reported effects of hydrologic attributes on trout survival are
likely to be increasingly important if, as predicted, climate change leads to greater extremes and variability of flow regimes. 相似文献
202.
Identification of novel virulence factors associated with signal transduction pathways in Alternaria brassicicola 总被引:1,自引:0,他引:1
203.
Felix B. Cruz Luciana Belver Juan C. Acosta Héctor J. Villavicencio Graciela Blanco Maria G. Cánovas 《Zoology (Jena, Germany)》2009,112(6):425-432
Several aspects of the biology of Phymaturus lizards including their herbivorous diet, specialized microhabitat use, and viviparous reproductive mode are highly conserved within the group. Here, we explore two aspects of Phymaturus thermal biology and test for the co-evolution among aspects of the thermal biology in these lizards, such as thermal preferenda and critical temperatures. Secondly, we explore correlations among variation in thermal biology with elevation and latitude. To do so, we used phylogenetically based comparative analyses (PCM) together with conventional statistics. Our results show that thermal biology for Phymaturus is conservative and our data do not suggest the co-evolution of thermal variables. Moreover, we detected low levels of variation in the thermal parameters studied, and no clear relationships between climatic and thermal variables. As a significant association between climatic and thermal variables could be demonstrated for a set of syntopic Liolaemus lizards, we suggest that thermal biology in Phymaturus lizards may be evolutionarily or ecologically constrained. 相似文献
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Pablo Mobili María de los Ángeles Serradell Sebastián A. Trejo Francesc X. Avilés Puigvert Analía G. Abraham Graciela L. De Antoni 《Antonie van Leeuwenhoek》2009,95(4):363-372
Since the presence of S-layer protein conditioned the autoaggregation capacity of some strains of Lactobacillus kefir, S-layer proteins from aggregating and non-aggregating L. kefir strains were characterized by immunochemical reactivity, MALDI-TOF spectrometry and glycosylation analysis. Two anti-S-layer
monoclonal antibodies (Mab5F8 and Mab1F8) were produced; in an indirect enzyme-linked immunosorbent assay Mab1F8 recognized
S-layer proteins from all L. kefir tested while Mab5F8 recognized only S-layer proteins from aggregating strains. Periodic Acid-Schiff staining of proteins
after polyacrylamide gel electrophoresis under denaturing conditions revealed that all L. kefir S-layer proteins tested were glycosylated. Growth of bacteria in the presence of the N-glycosylation inhibitor tunicamycin
suggested the presence of glycosydic chains O-linked to the protein backbone. MALDI-TOF peptide map fingerprint for S-layer
proteins from 12 L. kefir strains showed very similar patterns for the aggregating strains, different from those for the non-aggregating ones. No positive
match with other protein spectra in MSDB Database was found. Our results revealed a high heterogeneity among S-layer proteins
from different L. kefir strains but also suggested a correlation between the structure of these S-layer glycoproteins and the aggregation properties
of whole bacterial cells. 相似文献
207.
E. C. R. Tavano L. C. L. Stipp F. R. Muniz F. A. A. Mour?o Filho B. M. J. Mendes 《Biologia Plantarum》2009,53(2):395-399
In vitro organogenesis of Citrus volkameriana and C. aurantium was studied considering three explant types: epicotyl segment, internodal segment, and hypocotyl segment with attached cotyledon
fragment. The explants were cultured in medium according to Grosser and Gmitter (EME) supplemented with 0, 0.5, 1.0, 1.5,
and 2.0 mg dm− 3 6-benzyl-aminopurine (BAP), incubated firstly in darkness for 4 weeks, and then transferred to 16-h photoperiod for 2 weeks.
Comparing epicotyl and internodal segments, a higher percentage of responsive explants and a higher number of shoots per explant
were obtained with epicotyl segments, regardless of the BAP concentration. For C. volkameriana the highest percentage of responsive epicotyl segments (42 %) was obtained in EME with 1.0 mg dm−3 BAP, while for C. aurantium (59 %) in EME with 0.5 mg dm−3 BAP. The organogenesis efficiency was the best with the use of the hypocotyl segment with attached cotyledon fragment (77
% for C. volkameriana and to 75 % for C. aurantium). With this explant the morphogenesis occurred only in the hypocotyl region. The in vitro organogenesis was characterized by histological analyses showing that the morphogenic process started in the cambium region
near the explant cut end. 相似文献
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