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排序方式: 共有1023条查询结果,搜索用时 31 毫秒
991.
Javier Noe Serrano-López Katherin Soto-López Rosa Isabel Ochoa-Báez John O'Sullivan Felipe Galván-Magaña 《水产资源保护:海洋与淡水生态系统》2021,31(7):1624-1635
- Devil rays of the genus Mobula are subject to fishing exploitation worldwide and are considered vulnerable to overexploitation due to population reduction, which is evidenced by a decline in the number of catches of these animals.
- Limited biological knowledge on these species has forced the use of precautionary conservation measures in countries where intensive fishing occurs.
- This study aimed to describe biological data of interest for estimating the feasibility of the recovery of Mobula populations, emphasizing the reproductive activity of three endangered species of the genus Mobula (Mobula munkiana, Mobula thurstoni, and Mobula mobular) in the Gulf of California.
- Reproductive organs were collected during 7 years of commercial fishing (2001–2007), and data on population structure, sex ratio, gamete production, and the number of offspring per breeding period were obtained.
- Maturity stages were determined through histological analysis of the gonads for both sexes, and the size at maturity was estimated based on anatomical and histological characteristics of the specimens caught.
- Considering the wide global distribution of Mobula species, there is an urgent need to apply strict conservation measures, such as established fishery closures during the breeding season or the establishment of catch periods after specimens have reached sexual maturity, especially in the countries where these animals are caught.
992.
Mónica G. Candela Emmanuel Serrano Julie Sevila Luis León María Rosa Caro Hélène Verheyden 《Research in veterinary science》2014
Antibody prevalence for several infectious and parasitic diseases in a population of roe deer (Capreolus capreolus) inhabiting a mixed agricultural landscape (south of France) has been analyzed. Serological analyses with ELISA in 245 animals captured from 2008 to 2012 has been performed. We found a high prevalence of Toxoplasma gondii (46.4%), Chlamydophila abortus (17.27%) and Coxiella burnetii (11.26%) compared to other studies in Europe. Seroprevalence varied strongly among years for T. gondii (27–91%), C. abortus (0–42%) and C. burnetii (0–27%). T. gondii prevalence was lower in juvenile females, compared to juvenile males and adults of both sexes. Other pathogens had low prevalences: Neospora caninum (1.56%), Bovine herpesvirus 1 (1.17%, 2008/09; 1.1%, 2010/11), Mycoplasma agalactiae (1.45%, 2009/10), Mycobacterium avium subsp. paratuberculosis (0.9%) and Slow viruses (CAEV–MVV) (0.15%, 2008/10; 0%, 2011/12). Antibodies to bluetongue virus and pestiviruses were not found in any individual. 相似文献
993.
R. Abdollahi‐Arpanahi A. Pakdel A. Nejati‐Javaremi M. Moradi Shahrbabak G. Morota B.D. Valente A. Kranis G.J.M. Rosa D. Gianola 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2014,131(3):183-193
The aim of this study was to separate marked additive genetic variability for three quantitative traits in chickens into components associated with classes of minor allele frequency (MAF), individual chromosomes and marker density using the genomewide complex trait analysis (GCTA) approach. Data were from 1351 chickens measured for body weight (BW), ultrasound of breast muscle (BM) and hen house egg production (HHP), each bird with 354 364 SNP genotypes. Estimates of variance components show that SNPs on commercially available genotyping chips marked a large amount of genetic variability for all three traits. The estimated proportion of total variation tagged by all autosomal SNPs was 0.30 (SE 0.04) for BW, 0.33 (SE 0.04) for BM, and 0.19 (SE 0.05) for HHP. We found that a substantial proportion of this variation was explained by low frequency variants (MAF <0.20) for BW and BM, and variants with MAF 0.10–0.30 for HHP. The marked genetic variance explained by each chromosome was linearly related to its length (R2 = 0.60) for BW and BM. However, for HHP, there was no linear relationship between estimates of variance and length of the chromosome (R2 = 0.01). Our results suggest that the contribution of SNPs to marked additive genetic variability is dependent on the allele frequency spectrum. For the sample of birds analysed, it was found that increasing marker density beyond 100K SNPs did not capture additional additive genetic variance. 相似文献
994.
995.
In Peru, a new forest reform process laid the foundation for the establishment of a large sector of private small and medium-sized forest enterprises to practice responsible forest management. This paper analyzes the influence of a newly established concession system on forest landscape change. Specifically, the paper examines whether the concession system promoted and increased land-cover changes and changed fragmentation patterns between 2001 and 2010. Classified Landsat images at 2-year intervals from 2001 to 2003 and 2006 to 2010 were used to examine trajectories in forest, non-forest and regrowth areas. Non-linear changes were found to have occurred in each of the forest classes. Changes in fragmentation varied in size, density, aggregation and configuration over the study period. Forest reforms account for changes in specific land-cover classes through pattern dynamics within timber concessions. However, not all results relate to landscape pattern metrics. Although new forest legislation has been important in reorganizing the forest sector, other causal factors including levels of technological and managerial expertise, credit availability and law enforcement structures play a decisive role in the successive implementation of forest legislation. 相似文献
996.
During the last few years following the invasion of European tomato crops by the invasive South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), several indigenous larval parasitoid species were recorded as natural enemies of this pest. Necremnus cf. artynes (Walker) and to a lesser extent Stenomesius sp. nr. japonicus (Ashmead) (Hymenoptera: Eulophidae) have been frequently reported attacking T. absoluta in tomato greenhouses in Europe and they are considered as possible biocontrol agents. Few biological data are available on these two species, notably when they parasitize T. absoluta. Therefore, the present study documents their biology when parasitizing T. absoluta, and provides scientific bases for potential development of biological control programs relying on larval ectoparasitoids in invaded areas. We demonstrated the ability of the two parasitoid species to reproduce on T. absoluta as host on tomato plants. On average, N. cf. artynes female parasitized 28.5 larvae and killed 26.2 larvae during its life time whereas S. sp. nr. japonicus female was more long-lived and consequently more efficient; it parasitized 144.3 larvae and killed 90.1 larvae. In a second step, we also explored the effect of T. absoluta larvae instar on parasitism by S. sp. nr. japonicus and subsequent development of the parasitoid offspring. Best results were obtained with the third larvae instar with a higher number of offspring produced, bigger individuals and a higher proportion of females. Our results support the hypothesis that the two species are good candidates for biological control programs targeting T. absoluta in Europe. 相似文献
997.
Summary An analysis of the variability for genes encoding seven isozyme systems and storage proteins in a collection of cultivated and wild accessions of Lens is reported. The collection, which is part of the Spanish INIA Cenebank, contains the ssp. culinaris, orientalis, odemensis, nigricans and ervoides, and presents a high degree of genetic diversity both within and between the accessions. A total 25 loci were examined; of these, 18 were polymorphic (the 7 genes encoding storage proteins, and the following isozyme loci: Acp-1, Acp-2, Cpx-1, Cpx-2, Aat-p, Aat-m, Lap-1, Mdh-2, Mdh-3, Mdh-4 and 6pgd-p) and 7 were monomorphic (Aat-mb, Aat-c, Mdh-1, Mdh-5, 6pgd-2, Pgm-c and Pgm-p). The phylogenetic relationships between subspecies were analyzed using the allelic frequencies. The study suggests that orientalis and odemensis share more biochemical characters than the other subspecies, and that those subspecies keep an intermediate position between Lens culinaris and Lens nigricans. 相似文献
998.
Production of embryogenic tissues and regeneration of transgenic plants in cassava (Manihot esculenta Crantz) 总被引:3,自引:0,他引:3
Nigel J. Taylor Munyaradzi V. Masona Rosa Carcamo Thao Ho Christian Schöpke Claude M. Fauquet 《Euphytica》2001,120(1):25-34
Disorganised embryogenic tissues have been utilised as target tissues for transgene insertion and transgenic plant regeneration
in cassava (Manihot esculenta). The production of friable embryogenic callus in fourteen geographically diverse cassava cultivars, from which eleven were
established as embryogenic suspension cultures, is reported. Embryogenic tissues were similar in nature in all cultivars tested
although there was variation in the time required to generate friable callus and the growth rates of suspension cultures.
Regeneration of plants has been achieved from eight cultivars but varied significantly in efficiency, with cv. TMS 60444and
Line 2 from Zimbabwe being the most responsive. Tissues from the remaining eight cultivars became arrested at globular and
torpedo stages of regeneration indicating that they most likely process an inherent ability to produce plants but require
further research to allow this to be realised. Significant numbers of transgenic plants containing transgenes for putative
resistance to important viral diseases of cassava in addition to visual marker genes have been regenerated. Transgenic plants
from three the cultivars TMS 60444, Bonoua Rouge and M.Col 1505 were recovered after particle bombardment of embryogenic suspension
cultures. Correlation's have been made between abnormal leaf morphology and plant vigour with the use of embryogenic suspension
cultures for transgene insertion. As an result friable embryogenic callus is now being successfully utilsed as the target
tissue for genetic transformation and plant regeneration at ILTAB.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
999.
Summary Hemp cultivation is not new to the southern regions, but cultivated area is decreasing. Recently, there has been a rediscovery of this crop, as a result of requests from the producers of natural fibres.The paper synthesizes the studies recently set up in southern Italy, with the goal of evaluating the adaptation and the yield of recent genotypes and of new agronomic techniques. The study demonstrates that, with the exception of the monoicious cultivars, the new genotypes of hemp are adapted to the environmental conditions of the Mediterranean Europe, reaching productive standards not lower than those obtained in other environments.The use of irrigation is indispensable for overcoming the prolonged water deficit which hemp is subject to during its cultivation cycle. A good irrigation practice consists in the partial satisfaction of the water requirements. The experimental evidence indicates that the best productive results are obtained with the reintegration of 66% of the water lost through evapotranspiration.A further saving in water is obtained with the anticipation of the sowing period, with, however, a loss in productive potential.Hemp can be considered, in all respects, a species to reintroduce in the current cultivation systems of southern Europe. It will be possible to increase its potential provided that breeding supplied new varieties, more tolerant to low temperatures (in order to anticipate the sowing time), and able to obtain economically profitable yields with the use of limited irrigation. 相似文献
1000.
RC Bohrer PRA Rosa R Ferreira V Bordignon JFC Oliveira PBD Gonçalves 《Reproduction in domestic animals》2013,48(3):396-401
The growth factor receptor‐bound protein 14 (Grb14) is a cellular adapter protein belonging to the Grb7 family of proteins. Studies with human and rodent cells have demonstrated that Grb14 acts as a negative regulator of tyrosine kinase receptor signalling through the MAPK and PI3K pathways. In cattle, tyrosine kinase receptors are activated during follicular development but the role of Grb14 in this process has not yet been investigated. Therefore, the aim of the present study was to characterize Grb14 mRNA expression in ovarian somatic cells during follicular growth and deviation in cattle. We found Grb14 mRNA expressed in both granulosa and theca cells derived from follicles at different stages of development (3–5 , 6–8, >8 mm in diameter). The abundance of mRNA for Grb14 was higher in granulosa cells of subordinate compared with those from dominant follicles at days 3 and 4 of the follicular wave (p < 0.05). Further, there was a negative correlation between the abundance of mRNA for Grb14 and P450Arom in granulosa cells (R2 = 0.367; p < 0.05) and between the abundance of mRNA for Grb14 in granulosa cells and concentration of oestradiol in follicular fluid (R2 = 0.545; p < 0.05). In theca cells, the expression of Grb14 mRNA did not differ between dominant and subordinate follicles (p > 0.05). These findings suggest that Grb14 may play a regulatory role in granulosa cells during follicular deviation in cattle. 相似文献