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1.
Gonadotropin releasing hormone (GnRH) was given to 109 cows and heifers during the course of 224 superovulations. Follicle stimulating hormone (FSH) was administered twice daily (5 or 6 mg) for 3.5 to 4 days beginning on any of Days 9 to 14 of the estrous cycle; prostaglandin (45 mg PGF(2)alpha or 750 ug cloprostenol) was given in a split dose on the fourth day. Donor cows and heifers were placed into four groups according to previous superovulation treatments, which consisted of one to three treatments or of no previous treatment. Every other cow or heifer within each of the four subgroups was treated with GnRH (200 mug i.m.) at standing estrus. Only donors that exhibited estrus within 32 to 72 h after the first prostaglandin treatment were used in the study. Animals were inseminated artificially 12 and 24 h after standing estrus was first observed. No differences were noted in the number of ovulations, total ova or transferable embryos recovered from the GnRH or control groups; however, two interactions were detected. Cows given GnRH had fewer palpable corpora lutea than control cows (P < 0.05), but this difference was not seen in heifers. The second interaction was that GnRH seemed to depress ovulation rate in donors not previously superovulated, but this effect was not observed with subsequent superovulations. Cows yielded more total ova than heifers (P < 0.01). There was no difference in return to estrus between GnRH and control groups after a second prostaglandin treatment at the time of embryo recovery. Most donors within each group resumed cycling between 5 and 12 d after embryo recovery. 相似文献
2.
The mating ability of the different Adh genotypes of D. melanogaster, from three natural populations, was estimated as the number of females inseminated by a single male in a 24-hour period. The data indicate that populations of D. melanogaster vary in mating properties, but a common tendency was found in all of them: the heterozygous individuals, especially the males, show a relative advantage with respect to homozygotes. On the other hand, our results suggest that the differences in mating patterns observed between populations may be correlated with the different degree of Adh polymorphism found in them. 相似文献
3.
P Venault L Prado de Carvalho C L Brown R H Dodd J Rossier G Chapouthier 《Life sciences》1986,39(12):1093-1100
Certain pharmacological properties of methyl beta-carboline-3-carboxylate (beta-CCM), a benzodiazepine receptor ligand, have been investigated in chicks. Although beta-CCM has been established previously as an "inverse agonist" of benzodiazepine receptors in rodents, having effects opposite to those of benzodiazepines in a variety of tests, in chicks this compound had a different pharmacological profile. Firstly, in contrast to the overt convulsant action of beta-CCM in other species, beta-CCM (0.05-40 mg/kg) did not produce convulsions by itself in chicks, but it was only proconvulsant. Secondly and most surprisingly, beta-CCM, like diazepam, produced in chicks a sedation which could be blocked by the benzodiazepine receptor antagonist Ro 15-1788. Thus it appears that beta-CCM can function both as an agonist and as an inverse agonist in this animal. 相似文献
4.
J. P. Lewis Marta B. Collantes E. F. Pire Nélida J. Carnevale Silvia I. Boccanelli Susana L. Stofella D. E. Prado 《Plant Ecology》1985,60(2):67-90
This paper is a survey of the vegetation of the southeastern departments in the Province of Santa Fe (Argentina). The vegetation was analyzed following Braun-Blanquet's approach modified by Mueller-Dombois & Ellenberg (1974). The most relevant species of the region were placed in 25 groups according to their requirements or general behaviour. Most of the communities are herbaceous, and apart from the woody and some other miscellaneous ones they were grouped into three ecologically and floristically defined sets. The first set, the Stipa grasslands and related communities, which are characterized by the more or less abundant presence of Stipa hyalina, Stipa neesiana and Stipa papposa, comprises five different communities. The second, the halophilous communities, comprises five communities, the two Spartina ssp. grasslands, the halophilous prairies of Distichlis spicata, the short sedge Scirpus americanus communities and the ‘pela-dales’. The third, the hygrophilous communities, comprises nine communities which are not so well defined as the ones in the other sets. Besides, two further communities have been included, the Paspalum quadrifarium and the Melica macra tall grasslands. 相似文献
5.
Aphid activities during sieve element punctures 总被引:13,自引:0,他引:13
Aphid salivation in sieve elements and phloem sap ingestion were linked to waveforms in the Electrical Penetration Graph (EPG).
Non-viruliferousRhopalosiphum padi (L.) (Hemiptera, Aphididae) on barley yellow dwarf virus (BYDV) infected wheat could acquire the virus, which was used as
an indication for phloem sap ingestion, whereas virus inoculation by viruliferous aphids on healthy plants was associated
with salivation in sieve elements or other phloem cells. Probing was monitored and the waveforms recorded were related to
ELISA results of test plants. The EPG patterns A, B, and C are indicative of the stylet pathway phase, whereas patterns E1
and E2 reflect the phloem (sieve element) phase with an unknown activity (E1) or with ingestion and concurrent salivation
(E2). Aphids showing pathway and E1 rarely acquired virus, suggesting that little or no phloem sap ingestion can occur during
these patterns, whereas those showing additionally pattern E2 did so substantially, indicating phloem sap ingestion. The main
pattern related to virus inoculation was E1, although some aphids were able to inoculate plants during pathway. Pattern E1
clearly reflects the most important salivation into sieve elements. Pattern E2 had no clear contribution to virus inoculation,
supporting the present hypothesis that during this pattern the saliva is mixed with the phloem sap in the single canal at
the stylet tips and ingested immediately, without reaching the plant tissue. Sustained sap ingestion did not affect virus
inoculation. So, BYDV inoculation mainly occurs during the first period of a sieve element puncture which is always formed
by E1. Implications on persistent virus transmission are discussed. 相似文献
6.
Summary We have already shown that theachaetae-scute complex (AS-C) ofDrosophila is regulated by two genes,hairy andextramacrochaetae. Using mutants in these genes, we have analysed how different levels of expression of AS-C affect the pattern of chaetae. The results indicate that the spatial distribution of chaetae results from cell interactions, probably by a mechanism of lateral inhibition. The results are discussed in view of the different theories of pattern formation. 相似文献
7.
Fernando Ribas Prado Claude Giessner-Prettre Bernard Pullman 《Journal of theoretical biology》1978,74(2):259-277
The variation of the chemical shift of the protons of 5′-UMP and 5′-AMP is calculated as a function of χCN, ψ and ? torsion angles. The shift of H8 of 5′-AMP and H6 of 5′-UMP is found to be very sensitive to the value of χCN. For the anti conformations the shift of these protons is more sensitive to the value of the rotation about CS′-05′ than about C4′-CS′. For the protons of the ribose the calculations show that for the C2′-endo pucker H3′ and H2′ undergo the largest chemical shift variations when ? and ψ vary. The calculated variations are considered in relation with the role of the conformation of the nucleotides in the chemical shift variation between mono and polynucleotides and between the different helical structures of polynucleotides. 相似文献
8.
9.
A number of expeditions to the area of Salar de Atacama, Chile, 68° 15'W, 20° 30'S, have involved studies of the biological
and chemical features of Lake Tebenquiche, situated in the interior of the salar. Chemically, Tebenquiche is hypersaline,
with practically anoxic waters dominated by sodium and chloride ions but with high concentrations of sulphate also. The lake
is surrounded and invaded by macrophytes, dominated by Scirpus olmeyi and Juncus, which provide organic material for the formation of bacterial mats. The fauna of limnetic crustaceans is almost exclusively
of Artemia salina. The most important genera of bacteria are: Marinomonas, Halobacterium, Acinetobacter and the sulphur reductors Vibrio and Bacillus. The Cyanobacteria are represented exclusively by Oscillatoria. 相似文献
10.
Adiantum diphyllum, a species endemic to the coastal forests of Bahia State, Brazil, is characterized and distinguished from other species ofAdiantum with anastomosing veins, elongate sori, and venuloid idioblasts.
Adiantum diphyllum, uma espécie endêmica das florestas costeiras do leste do Brasil. é caracterizada e distinta das outras espécies deAdiantum com nervuras anastomosadas, soros alongados e idioblastos entre as nervuras.相似文献