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71.
Strong LC 《Science (New York, N.Y.)》1945,101(2633):608-609
72.
Juan Manuel Blanco George F Gee David E Wildt Ann M Donoghue 《Journal of zoo and wildlife medicine》2002,33(1):1-7
Wild raptors brought into an ex situ environment often have poor semen quality that is further compromised by urine contamination. Generally, it is believed that in birds, artificial insemination into the cloaca or caudal vagina of females requires large doses of high-quality spermatozoa to maximize fertility. In an effort to define and overcome some of the challenges associated with reproduction in wild raptors, the objectives of this study were to 1) evaluate the frequency, impact, and remediation of urine contamination in fresh ejaculates for the purpose of maintaining sperm motility and viability in vitro, and 2) develop a deep insemination method that allows low numbers of washed sperm to be placed directly into the magnum to increase the probability of producing fertilized eggs. The species evaluated include golden eagle (Aquila chrysoetos), imperial eagle (A. adalberti), Bonelli's eagle (Hiernaetus fasciatus), and peregrine falcon (Falco peregrinus). Semen samples were collected and pooled by species, and a minimum of 25 pooled ejaculates per species were evaluated for urine contamination, pH, sperm viability, and sperm motility; the samples were either unwashed or washed in neutral (pH 7.0) or alkaline (pH 8.0) modified Lake's diluent. Female golden eagles and peregrine falcons were inseminated via transjunctional, intramagnal insemination with washed spermatozoa from urine-contaminated samples. Urine contamination occurred in 36.8 +/- 12.8% (mean +/- SEM) golden eagle, 43.1 +/- 9.1% imperial eagle. 28.7 +/- 16.1% Bonelli's eagle, and 48.2 +/- 17.3% peregrine falcon ejaculates. The pH in urine-contaminated semen samples ranged from 6.48 +/- 0.3 to 6.86 +/- 0.2, and in noncontaminated samples it ranged from from 7.17 +/- 0.1 to 7.56 +/- 0.1. Sperm viability and motility were reduced (P < 0.05) in all species for unwashed vs. washed sperm after 30 min incubation at room temperature. Two peregrine falcon chicks and one golden eagle chick hatched after intramagnal insemination. This study demonstrates that urine contamination, a common and lethal acidifier in manually collected raptor ejaculates, can be circumvented by immediate, gentle seminal washing. Furthermore, these processed sperm, when deposited by transjunctional intramagnal insemination, can produce live young. 相似文献
73.
74.
75.
Ann Magee 《Asia Pacific viewpoint》2001,42(1):35-45
In New Zealand while women dominate leadership positions in constitutional, political and business areas, gender inequality remains entrenched. Despite significant gains in rights (employment, pay equity, property), as a group women earn less and perform more family care and unpaid work than men. In part these disparities result from the economic restructuring of the last 15 years which saw a loss in unskilled manufacturing jobs, less social support and greater rewards to business and public sector elites. Maori and Pacific Island women are the most disadvantaged groups. Labour/Alliance government initiatives to reduce poverty particularly among Maori and Pacific Island peoples by strengthening access to health and education services and supporting and replicating successful community initiatives are also likely to benefit other low income women. 相似文献
76.
José F. Barbosa-Neto Carlos M. Hernández Louise S. O’Donoughue Mark E. Sorrells 《Euphytica》1997,98(1-2):59-67
Genetic progress through selection is directly related to the amount of variability present in the population and the quality
of genes contributed by the parents. Genetic relationships between lines were studied using DNA marker-based estimates of
genetic similarity. A statistical methodology using the width of a confidence interval was developed to determine the number
of probes to be surveyed and the precision in the estimation of genetic distance between pairs of cultivars. Precision was
affected by type of genetic distance used, the number of cultivars, and amount of genetic diversity present in the studied
group. The width of a (1-α)% confidence interval decreased as the number of RFLP fragments increased. Oat and wheat diversity
studies were used to illustrate the methodology.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
77.
Ann Mari Fransson 《Soil biology & biochemistry》2007,39(5):1213-1217
Plant roots and soil microorganisms contain significant quantities of low molecular weight (MW) phosphorylated nucleosides and sugars. Consequently, upon death these can represent a significant input of organic-P to the soil. Some of these organic-P substrates must first be dephosphorylated by phosphatases before being assimilated by the soil microbial community while others can be taken up directly from soil solution. To determine whether sorption or phosphatase activity was limiting the bioavailability of low MW organic-P in soil we compared the microbial uptake and C mineralization of a range of 14C-labeled organic-P substrates [glucose-6-phosphate, adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP)] to that of the parent compounds (adenosine and glucose). In a fertile grassland soil we showed that at low organic-P substrate concentrations (<0.5 mM) phosphatase activity did not limit microbial uptake or mineralization in comparison to their non-phosphorylated counterparts. However, at high substrate concentrations (1-10 mM) the mineralization of the organic-P compounds was significantly lower than that of the non-phosphorylated compounds suggesting that phosphatase activity or microbial transporter capacity limited bioavailability. Sorption to the solid phase followed the series glucose<adenosine<G-6-P<AMP<ADP=ATP. However, sorption of the organic-P compounds to the solid phase did not appear to greatly affect bioavailability. The high adenosine mineralization capacity of the microbial biomass suggests that nucleosides may represent a significant source of C and N to the soil microbial biomass. We conclude that at low organic-P substrate concentrations typical of those in soil, neither phosphatase activity nor sorption greatly limits their bioavailability. 相似文献
78.
Colin Southwell David Borchers Charles G. M. Paxton Louise Burt William de la Mare 《Journal of Agricultural, Biological & Environmental Statistics》2007,12(1):41-54
We use line transect detection functions together with generalized linear and additive models to estimate detection probability
when detection on the line (“g(0)”) may not be certain. The methods provide a flexible way of modeling detection probability
for independent observer surveys, and for investigating the effects of explanatory variables. Analysis of data from an aerial
survey of pack-ice seals produced g(0) estimates substantially below 1 for some observers (it varied from 0.80 to 0.98), demonstrated a fairly complex dependence
of detection probability on covariates, and showed negative correlation between observers’ search width and their g(0). In addition to illustrating the utility of generalized additive models for capturing the effect of covariates on detection
probability, the analysis suggests that detection functions may be sufficiently variable that use of g(0) correction factors obtained from other surveys would be inadvisable. We recommend that estimation of g(0) be considered for all aerial surveys; if g(0) is found to be very close to 1, estimation from subsequent surveys under the assumption that it is 1 may be reasonable,
but without any estimation of g(0), the assumption that it is 1 is a matter of faith. 相似文献
79.
Abscisic acid (10?4M) applied via absorbent discs bound to the stems of 6 wk oldE. camaldulensis seedlings caused changes in leaf shape and orientation similar to those induced by nutritional and water stress. Seedlings from the driest provenance, Tennant Creek, were more responsive to ABA than seedlings from the wettest provenance, Katherine, and the response of Petford seedlings was intermediate. Likewise, Tennant Creek seedlings were most, and Katherine seedlings least, responsive to water and/or nutritional stress. Seedlings that responded to the application of ABA produced prematurely strengthened, linear leaves with the lamina rotated from horizontal to vertical. The ability of Tennant Creek seedlings to readily assume this form may be a specific adaptation for the particularly difficult conditions in their natural environment. 相似文献
80.
Changes in fruit antioxidant activity among blueberry cultivars during cold-temperature storage 总被引:10,自引:0,他引:10
Connor AM Luby JJ Hancock JF Berkheimer S Hanson EJ 《Journal of agricultural and food chemistry》2002,50(4):893-898
Antioxidant activity, total phenolic content, anthocyanin content, and six other fruit characters including titratable acid concentration, soluble solids, firmness, and percentage of bruised berries were determined for nine blueberry (Vaccinium L. sp.) cultivars at harvest and at various postharvest intervals after storage at 5 degrees C. Berries from MSU-58, Brigitta, and Legacy stored successfully for 7 weeks, Bluegold stored for 3-5 weeks, Bluecrop, Elliott, and Nelson stored for 3 weeks, and Jersey and Little Giant stored for fewer than 3 weeks. During the time they retained marketable quality, one cultivar (MSU-58) demonstrated a 29% increase in antioxidant activity. None of the cultivars showed a significant decrease from the harvest antioxidant activity value during storage. Antioxidant activity, total phenolic content, and anthocyanin content were strongly correlated with each other (r = 0.87-0.99, P < 0.01). All three parameters were moderately correlated with soluble solids (r = 0.47, P < or =0.05; r = 0.44, P < or = 0.05; and r = 0.64, P < or = 0.01, respectively), and antioxidant activity and total phenolic content were both moderately correlated with pH (r = 0.53 and 0.49, respectively; P < or = 0.05). However, antioxidant activity, total phenolic content, and anthocyanin content showed no correlation with firmness, percent severely bruised berries, or weight loss. Antioxidant activity and total phenolic content at harvest both correlated with titratable acidity at harvest (r = 0.68, P < or = 0.05 and r = 0.70, P < or = 0.05, respectively) on a cultivar mean basis. Berries from Elliott were also harvested from plants at two levels of bush ripeness (30-50% and 60-80% ripe berries on plants) and separated into three fruit maturity classes on the basis of percent blue color. The level of bush ripeness had no significant effect on antioxidant activity, total phenolic content, or anthocyanin content; however, fruit maturity had a significant effect on antioxidant activity, total phenolic content, and anthocyanin content, and bush ripeness x fruit maturity interactions were significant for these three traits. Berries with 50-75% blue coloration harvested from bushes with 60-80% mature fruit showed a significant increase in antioxidant activity, total phenolic content, and anthocyanin content during the first 3 weeks in storage. Our results demonstrate that increases in antioxidant activity, total phenolic content, and anthocyanin content may occur in the blueberry during cold storage and are cultivar-dependent. The increases that occur in immature fruit, such as in Elliott, may be advantageous for producers who wish to delay marketing of the fruit. 相似文献