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151.
Kumar S Dagar SS Mohanty AK Sirohi SK Puniya M Kuhad RC Sangu KP Griffith GW Puniya AK 《Die Naturwissenschaften》2011,98(6):457-472
Methanogens, the members of domain Archaea are potent contributors in global warming. Being confined to the strict anaerobic environment, their direct cultivation as
pure culture is quite difficult. Therefore, a range of culture-independent methods have been developed to investigate their
numbers, substrate uptake patterns, and identification in complex microbial communities. Unlike other approaches, fluorescence
in situ hybridization (FISH) is not only used for faster quantification and accurate identification but also to reveal the
physiological properties and spatiotemporal dynamics of methanogens in their natural environment. Aside from the methodological
aspects and application of FISH, this review also focuses on culture-dependent and -independent techniques employed in enumerating
methanogens along with associated problems. In addition, the combination of FISH with micro-autoradiography that could also
be an important tool in investigating the activities of methanogens is also discussed. 相似文献
152.
Godoy JM de Oliveira MS de Almeida CE de Carvalho ZL da Silva ER Fernandes Fda C Pitanga FL Danelon OM 《Journal of environmental radioactivity》2008,99(4):631-640
Twenty ropes with 400 Perna perna mussels seeds (3 cm shell size) were set-up on floating structures at Cabo Frio Island, Arraial do Cabo, approximately 100 km northeast of Rio de Janeiro city. A rope was taken out on a monthly basis, and the shell sizes of 100 seeds were measured. The haemolymph of 10 male and 10 female individuals was taken, and the same individuals were separated for 210Po/210Pb determination. After one year of monthly sampling, no clear correlation was observed between the 210Po concentration, mussel's age and weight. A mean 210Po concentration of 155 Bq kg(-1) wet weight basis, was obtained, which is comparable with data reported in the literature. The radiation dose did not have any observable effect on the micronuclei frequency and DNA breaks in the mussels. This was probably due to the low dose rate, 0.02 mGy d(-1), in comparison with the suggested potential dose limit of 10 mGy d(-1). 相似文献
153.
154.
The current study represents a preliminary investigation made into the influence of cattle grazing in the area of a bauxite
quarry (Comarnic–Poieni, Romania) on the cow milk chemistry. Weathering and surface runoff in the bauxite quarry contaminate
the local chemistry of the soil, vegetation and water. During cattle transhumance, cyclic feeding patterns occur, with grazing
alternating between clean pastures and the area of the quarry. Soil and water samples were collected from the contaminated
area of the quarry. Raw milk samples were collected during two stages, corresponding to the periods of grazing on clean pasture
and the quarry area, respectively. Based on the obtained data, the relationship between cattle grazing and the composition
of milk was interpreted. Preliminary results indicated a direct correlation of increased concentration of Al in the milk,
following grazing in the bauxite quarry. 相似文献
155.
Biodegradation of α, β, γ and δ hexachlorocyclohexane (HCH) isomers was studied in broth medium and soil microcosm by Bacillus circulans and Bacillus brevis isolated from contaminated soil. Degradation of α and γ isomers by both the bacterial isolates was higher than thermodynamically stable β and δ isomers. However, B. circulans was found more effective than B. brevis for β and δ isomers. Maximum rate of degradation was recorded at 150 mg/L followed by 100 and 50 mg/L. Soil microcosm study revealed maximum degradation of HCH isomers in the treatment containing natural soil, pesticide and bacterial inocula than the treatment having sterilised soil, pesticide and bacterial isolates. Chloride release was positively co-related with HCH degradation in broth medium as well as in soil microcosm, suggesting that B. circulans and B. brevis hold promising potential by having efficient enzyme(s) required for dechlorination of HCH from contaminated sites. 相似文献
156.
Natasha Tigreros Monica A. Mowery Sara M. Lewis 《Behavioral ecology and sociobiology》2014,68(9):1539-1547
While the phenomenon of male mate choice has attracted considerable attention in the last two decades, whether this sexual selection mechanism could drive the evolution of female ornaments remains poorly understood. Here, we used experimental manipulation of female wing coloration to investigate male mate choice in Pieris rapae, a gift-giving butterfly. Further, we tested whether males’ nutritional status influenced their mating preferences by subjecting larvae to short periods of starvation. We found that males showed significantly more mating approaches toward control females with more colorful wings (higher pteridine content), and that this preference was strongest in low-nutrition males. Additionally, a study of field-collected females revealed that pteridine-based wing coloration was positively correlated with female egg load, which suggests such ornaments may signal female quality. Pteridine-based ornaments are widespread in nature, however their potential as honest signals in male mate choice remains largely unexplored. This work furthers our understanding of how male mate choice and female ornamentation may evolve in species whose mating systems include nutritional nuptial gifts. 相似文献
157.
In the present work, the gasification with air of dehydrated sewage sludge (SS) with 20wt.% moisture mixed with conventional woody biomass was investigated using a pilot fixed-bed updraft gasifier. Attention was focused on the effect of the SS content on the gasification performance and on the environmental impact of the process. The results showed that it is possible to co-gasify SS with wood pellets (WPs) in updraft fixed-bed gasification installations. However, at high content of sewage sludge the gasification process can become instable because of the very high ash content and low ash fusion temperatures of SS. At an equivalent ratio of 0.25, compared with wood pellets gasification, the addition of sewage sludge led to a reduction of gas yield in favor of an increase of condensate production with consequent cold gas efficiency decrease. Low concentrations of dioxins/furans and PAHs were measured in the gas produced by SS gasification, well below the limiting values for the exhaust gaseous emissions. NH(3), HCl and HF contents were very low because most of these compounds were retained in the wet scrubber systems. On the other hand, high H(2)S levels were measured due to high sulfur content of SS. Heavy metals supplied with the feedstocks were mostly retained in gasification solid residues. The leachability tests performed according to European regulations showed that metals leachability was within the limits for landfilling inert residues. On the other hand, sulfate and chloride releases were found to comply with the limits for non-hazardous residues. 相似文献
158.
Monica C. Higgins 《组织行为杂志》2001,22(6):595-618
This paper investigates the social context in which career decisions are made. Results show that beyond individual‐level factors such as demographics and work history, individuals' decisions to change careers are socially embedded. Findings suggest that the greater the diversity of an individual's network of advisors, the greater the likelihood that an individual will change careers. In addition, this paper explores the mechanisms through which different subsets of advice relationships — instrumental versus psychosocial — affect the decision to change careers. Results show that the greater the diversity of an individual's set of instrumental relations, the greater the number of offers he or she receives during the job search process and, further, that the number of offers received is positively related to the likelihood of changing careers. The diversity of an individual's set of psychosocial relations was related to his or her confidence to overcome career obstacles. However, confidence was not, in turn, related to career change, counter to expectations. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
159.
Monica R. Lara 《Marine Biology》2008,154(1):51-64
Larval fishes likely use a variety of settlement cues to locate and navigate toward the habitats they will inhabit as juveniles.
Information about the morphology and state of development of the sensory organs of larval stages of fishes provides insight
into their capabilities at the time of settlement. The peripheral olfactory organ of wild-caught late-stage larvae and early
juveniles and some adults of 14 species of the Caribbean reef fishes wrasses (Labridae), parrot fishes (Scaridae) and damselfish
(Pomacentridae) were examined using scanning electron microscopy and compared in terms of settlement specificity. Ages in
days after hatching and days post-settlement were determined from the otoliths. Morphology of the nares and the olfactory
epithelium are described for these species by stage. The separation of the anterior and posterior nares occurred before settlement
in the labrids but in some specimens of scarids this separation was not complete by the time of settlement. Densities of ciliated
and microvillous receptor cells and non-sensory ciliated epithelial cells were calculated. Densities of ciliated receptor
cells ranged from 0.389 μm−2 in a specimen of Thallasoma bifasciatum to 0.0057 μm−2 in Bodianus rufus and of microvillous receptor cells from 0.038 μm−2 in a Clepticus parrae juvenile to 0.266 μm−2 in a juvenile Doratonotus megalepis. Densities of non-sensory cilia, also associated with high olfactory ability, were also high. The olfactory organ in wrasses
is well developed prior to settlement and is comparable to that of adult fishes. The possible role of olfaction in larval
schooling, reef cue detection and orientation toward habitat at settlement is discussed.
相似文献
Monica R. LaraEmail: |
160.
Susan E. Ford V. Monica Bricelj Christophe Lambert Christine Paillard 《Marine Biology》2008,154(2):241-253
The known negative effects of shellfish toxin-producing dinoflagellates on feeding, burrowing and survival of some bivalve
mollusks has prompted questions concerning whether they might also impair the internal defense system of affected bivalves
and make them more susceptible to disease agents. The primary components of the cellular defense system are hemocytes. Many
toxic dinoflagellates are too large to be ingested whole by hemocytes and would most likely be exposed to intracellular toxins
only after the algae are consumed, broken down, and the water-soluble toxins, released. Therefore, we conducted a series of
experiments in which hemocytes from two suspension-feeding bivalves—the Manila clam, Ruditapes philippinarum, and the softshell clam, Mya arenaria—were exposed in vitro to filtered extracts of one highly toxic paralytic shellfish toxin (PST)-producing and one nonPST-producing
strain of Alexandrium tamarense (isolates PR18b, 76 ± 6 STXeq cell−1 and CCMP115, with undetectable PST, respectively). We measured adherence and phagocytosis, two hemocyte attributes known
to be inhibited by bacterial pathogens and other stressors. We found no measurable effect of a cell-free extract from a highly
concentrated suspension of the PST-producing strain on hemocytes of either bivalve species. Instead, extract from the nonPST-producing
strain had a consistent negative effect on both clams, resulting in significantly lower adherence and phagocytosis compared
to strain PR18b and filtered seawater controls. The bioactive compound produced by strain CCMP115, which has yet to be characterized,
may be similar to the PST-independent allelopathic compounds described for Alexandrium spp., which act on other plankters. These compounds and those produced by other harmful algae are known to cause immobilization,
cellular deformation and lysis of co-occurring target organisms. Thus, nonPST producing Alexandrium spp., which do not cause paralysis and burrowing incapacitation of clams, may still produce a compound(s) that has negative
effects not only on hemocytes, but on other molluscan cell types and their functions, as well. 相似文献