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541.
In fast, glycolytic muscles, oxidative phosphorylation presumably facilitates recuperation from exhaustive exercise and supports growth and maintenance metabolism. Given the shifts in pH with extensive glycolytic activity, the pH optima of mitochondrial processes should indicate whether mitochondria are adapted for recuperation from exercise or for growth and maintenance. We examined this question using mitochondria from the phasic adductor muscle of the scallop, Euvola (Pecten) ziczac, collected from the Golfo de Cariaco, Venezuela in 1992 and 1993. Scallop muscle mitochondria showed well coupled oxidation of glutamate and pyruvate at pH 7.0 and 6.4. The preferred substrates (glutamate, pyruvate and succinate) were oxidized at approximately 40 nmol O2 min-1 mg-1 mitochondrial protein at 25°C, while malate and glutamine were oxidized at 75% and proline at 30% of these rates. Neither palmitoyl carnitine nor aspartate were oxidized. Succinate oxidation was not coupled to ADP utilization at pH 7.0 but was somewhat coupled at pH 6.4. Generally, State 3 rates of oxygen uptake were similar at pH 7.0 and 6.4. Maximal rates of oxidation of glutamate and pyruvate showed broad pH optima. For both glutamate and pyruvate, the highest respiratory control ratio (RCR) values were found at pH 6.5. The saturation curves of scallop muscle mitochondria for pyruvate, glutamate and ADP were well described by the Michaelis-Menten equation. The affinity for pyruvate was greater at pH 6.4 (apparent K
m, app=0.013 mM) than at pH 7.0 (K
m, app=0.026 mM) while the affinity for ADP (K
m, app=0.015 mM) and that for glutamate (K
m, app=0.55 mM) changed little with pH. The ADP affinity was the same whether pyruvate or glutamate was the carbon substrate. The combination of maintenance of sensitivity to ADP with an enhanced affinity for pyruvate at acidic pH values should facilitate recuperation from bouts of glycolytic activity. Scallops harvested in September and those harvested in January differed in the maximal rates of glutamate and pyruvate oxidation. 相似文献
542.
Cadmium and Zinc content was determined in organs of the Japanese scallopMizuhopecten yessoensis, collected in 1984 from the Sea of Japan and aged between 1 and 8 yr. Under conditions of background Cd, Cd concentration in hepatopancreas and kidney increased linearly with age from 39 to 400µg g?1 dry wt in hepatopancreas, and from 100 to 640µg g?1 dry wt in kidney. Such a pattern was not determined for Zn. Cd concentration in muscle, mantle and gill did not exceed 6µg g?1 dry wt in the oldest scallops. In subcellular fractions of the hepatopancreas, cytosolic Cd accounted for 71.7% in 1-yr-old scallops and 98.8% in 8-yr-olds. A similar ratio was established for gills, although gill Cd content was an order of magnitude lower. Analysis of Cd distribution in cytoplasmic proteins (of different molecular weight) in the hepatopancreas, showed that the amount of Cd bound to metallothionein-like proteins increases with scallop growth. A considerable amount of Cd also was detected in high molecular weight proteins. Thus, Cd accumulation, with age, in organs of the Japanese scallop is due to metal binding by cytoplasmic proteins. 相似文献
543.
Summary Spatial relationships of white-footed mouse (Peromyscus leucopus) dams and their offspring and of littermates post-weaning were determined to evaluate if their dispersion was sufficient to prevent inbreeding. Mothers tended to leave their first nest site and establish another nest site within or near their original home range. Daughters inherited part of the maternal home range but sons dispersed. During the following breeding season, sons were not in proximity to their mothers or sisters. Daughters, however, frequently attained sexual maturity and bred within the home range of males that could have been their fathers. Differential dispersal of male and female juveniles reduces the probability of mother-son and brother-sister matings, but there is no obvious dispersal-related mechanism to prevent father-daughter matings. 相似文献
544.
Adam R. Smith William T. Wcislo Sean O’Donnell 《Behavioral ecology and sociobiology》2007,61(7):1111-1120
Facultatively solitary and eusocial species allow for direct tests of the benefits of group living. We used the facultatively
social sweat bee Megalopta genalis to test several benefits of group living. We surveyed natural nests modified for observation in the field weekly for 5 weeks
in 2003. First, we demonstrate that social and solitary nesting are alternative behaviors, rather than different points on
one developmental trajectory. Next, we show that solitary nests suffered significantly higher rates of nest failure than did
social nests. Nest failure apparently resulted from solitary foundress mortality and subsequent brood orphanage. Social nests
had significantly higher productivity, measured as new brood cells provisioned during the study, than did solitary nests.
After accounting for nest failures, per capita productivity did not change with group size. Our results support key predictions
of Assured Fitness Return models, suggesting such indirect fitness benefits favor eusocial nesting in M. genalis. We compared field collections of natural nests to our observation nest data to show that without accounting for nest failures,
M. genalis appear to suffer a per capita productivity decrease with increasing group size. Calculating per capita productivity from
collected nests without accounting for the differential probabilities of survival across group sizes leads to an overestimate
of solitary nest productivity. 相似文献
545.
Nadine C. Chapman Benjamin P. Oldroyd William O. H. Hughes 《Behavioral ecology and sociobiology》2007,61(8):1185-1194
Which task a social insect worker engages in is influenced by the worker’s age, genotype and the colony’s needs. In the honeybee,
Apis mellifera, genotype influences both the age a worker switches tasks and its propensity of engaging in specialist tasks, such as water
collecting, which only some workers will perform. In this study, we used colonies with natural levels of genetic diversity
and manipulated colony age demography to drastically increase the stimuli for the generalist tasks of foraging and nursing,
which all workers are thought to engage in at some point in their lives. We examined the representation of worker patrilines
engaged in nursing and foraging before and after the perturbation. The representation of patrilines among foragers and nurses
differed from that of their overall colony’s population. In the case of foraging, over- and underrepresentation of some patrilines
was not simply due to differences in rates of development among patrilines. We show that replacement foragers tend to be drawn
from patrilines that were overrepresented among foragers before the perturbation, suggesting that there is a genetic component
to the tendency to engage in foraging. In contrast, the representation of patrilines in replacement nurses differed from that
in the unperturbed nursing population. Our results show that there is a genetic influence on even the generalist tasks of
foraging and nursing, and that the way patrilines in genetically diverse colonies respond to increases in task stimuli depends
upon the task. The possible significance of this genetic influence on task allocation is discussed.
Electronic supplementary material Supplementary material is available in the online version of this article at doi: and is accessible to authorized users. 相似文献
546.
LUIGI MAIORANO†‡ ALESSANDRA FALCUCCI† EDWARD O. GARTON† LUIGI BOITANI 《Conservation biology》2007,21(6):1433-1444
Abstract: The Natura 2000 network is the most important conservation effort being implemented in Europe. Nevertheless, no comprehensive and systematic region—or nationwide evaluation of the effectiveness of the network has been conducted. We used habitat suitability models and extent of occurrence of 468 species of vertebrates to evaluate the contribution of the Natura 2000 network to biodiversity conservation in Italy. We also estimated the population size of 101 species inside the Natura 2000 network to assess its capacity to maintain or improve the population status of listed species. In general the Italian Natura 2000 did not seem to integrate existing protected areas well. The Natura 2000 network increased from 11% to 20% the area devoted to conservation in Italy and the coverage provided to areas with high biodiversity. Nevertheless, some areas with high numbers of species were devoid of conservation areas, and more than 50% of the highly irreplaceable areas were not considered in the system. Moreover, the Natura 2000 network cannot maintain 44–80% (depending on the taxa considered) of the species in a "favorable conservation status" under World Conservation Union Red List criteria. The Natura 2000 network is probably stronger than the results of our analyses suggest. The system is based on a site-specific expert-based strategy and is driven by direct and detailed knowledge of local diversity. Nevertheless, if Natura 2000 is taken to represent the final point of all the EU conservation policies, it will inevitably fail. Its role in conservation could be enhanced by integrating the Natura 2000 system into a more general strategy that considers natural processes and the ecological and evolutionary mechanisms underlying these processes. 相似文献
547.
A.?LebedevEmail author N.?Sinikova S.?Nikolaeva O.?Poliakova M.?Khrushcheva S.?Pozdnyakov 《Environmental Chemistry Letters》2003,1(1):107-112
To estimate air pollution snow samples were collected in March 2001 at six sites in the vicinity of the Kostomuksha factory
in Karelia. Seventy-two chemical elements and more than 200 individual organic compounds were identified by inductively coupled
plasma mass spectrometry (ICP-MS) and gas chromatography mass spectrometry (GC-MS). It was found that the levels of Li, B,
Al, Fe, Ni, Cu, Zn, Hg, Mn, Mo as well as hydrocarbons, phthalates and phenols exceeded the existing maximum allowable concentrations.
A list of toxicants emitted with the factory exhausts and a list of priority pollutants for Kostomuksha were compiled. The
impact of the exhausts of the Kostomuksha factory on the environment in Finland is relatively small.
Electronic Publication 相似文献
548.
Palumbo-Roe B Cave MR Klinck BA Wragg J Taylor H O'Donnell KE Shaw RA 《Environmental geochemistry and health》2005,27(2):121-130
Jurassic ironstones outcropping over parts of eastern England give rise to soils with arsenic concentrations in excess of
the UK soil guideline value of 20 mg kg−1 for residential areas. Total arsenic concentrations were determined for 73 ironstone derived soils and bioaccessible arsenic
determined using an in vitro physiologically based extraction test. The bioaccessible arsenic concentration for these soils was found to be well below
the soil guideline value with a mean concentration of 4 mg kg−1 and a range of 2–17 mg kg−1. The bioaccessible fraction ranges from 1.2 to 33%. Data from a sequential extraction test based on the use of aqua regia
as the main extractant is presented for a subset of 20 of the soils. Chemometric data reduction is used to demonstrate that
the bioaccessible arsenic is mainly contained within calcium iron carbonate (sideritic) assemblages and only partially iron
aluminosilicates, probably berthierine, and iron oxyhydroxide phases, probably goethite. It is suggested that the bulk of
the non-bioaccessible arsenic is bound up with less reactive iron oxide phases. 相似文献
549.
O. Barneah I. Brickner M. Hooge V. M. Weis T. C. LaJeunesse Y. Benayahu 《Marine Biology》2007,151(4):1215-1223
Epizoic worms were found to occur on certain coral colonies from reefs off the coast of Eilat (Red Sea). We identified 14
coral species infested by acoelomorph worms at a depth range of 2–50 m. The host corals were all zooxanthellate and included
both massive and branching stony corals and a soft coral. Worms from all hosts were identified as belonging to the genus Waminoa and contained two distinct algal symbionts differing in size. The smaller one was identified as Symbiodinium sp. and the larger one is presumed to belong to the genus Amphidinium. Worm-infested colonies of the soft coral, Stereonephthya cundabiluensis, lacked a mucus layer and exhibited distinct cell microvilli, a phenotype not present in colonies lacking Waminoa sp. In most cases, both cnidarian and Acoelomorph hosts displayed high specificity for genetically distinctive Symbiodinium spp. These observations show that the epizoic worms do not acquire their symbionts from the “host” coral. 相似文献
550.
Feeding in early life stages of the sedentary snail Crepidula is effected both by the use of the radula and by filtering with the gill. The present study is a contribution to the knowledge
of the mechanisms of feeding by early juvenile snails of Crepidula fecunda. Experimental observations were made on specimens of known ages as they were fed constant concentrations of microalgae in
the presence of a primary biological film on a glass substrate. Feeding activity was filmed under the microscope, and images
were digitized for the identification and quantification of feeding structures. A morphological analysis was made of the structures
associated with this process. Results showed that the radula was functional beginning in 1-day-old juveniles, and the gill
functioned in respiration. Gill function in filter-feeding began in juveniles of 9 days old when dorsal and ventral ciliation
had developed, as well as the food pouch. The latter structure begins activity as soon as the gill starts food collection.
Osphradia appeared simultaneous with development of the filter feeding capacity by the gill. In their earliest stages after
metamorphosis, the young snails begin life by radular scraping of primary biofilms, gradually shifting to filter feeding as
the gill developed a critical number of filaments and cilia. 相似文献