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991.
In 72 newborn children (37 boys and 35 girls) who suffered from prenatal hypoxia and were born in an asphyxic state, we measured
the level of melatonin in the umbilicial blood and observed clinical manifestations of the adaptation/stress syndrome. These
data were compared with the results of morphological examination of the epiphyses from 27 stillborns (15 boys and 12 girls)
who perished because of heavy prenatal hypoxia. The level of melatonin in the blood of ill newborn girls was much higher than
that in boys, and both these indices were about two times higher than those in respective groups of healthy newborn children.
At the same time, the pathomorphological examination showed that active epiphyseal cell units in the male fetuses were much
more numerous. The results show that the epiphysis plays a significant role in determination of the sex-related dimorphism
of the adaptation/stress syndrome in newborn children suffering from hypoxia- and asphyxia-evoked heavy CNS damage. The reasons
and consequences of more intensive morphofunctional loading of the epiphyseal system in the male fetuses are discussed. 相似文献
992.
993.
994.
The single enlarged claw of male sand fiddler crabs, Uca pugilator, is used in contests for control of breeding burrows. The larger of the two contestants has the larger claw and usually wins. Males use one or more of 10 agonistic elements that vary in intensity from a no-contact extension of the claw to the flip of an opponent. We used the sequence of elements employed and the duration of unstaged, naturally occurring contests in a South Carolina salt marsh to evaluate three models of extended contests: (1) energetic war of attrition, (2) cumulative assessment and (3) sequential assessment. Contests usually began with elements of low action intensity and often proceeded to elements of high intensity. Elements of higher intensity were correlated with both contest duration and the number of contest elements. Contest duration increased as opponents became more evenly matched in size, a result consistent with both cumulative and sequential assessment models. Variation in duration increased as the relative sizes of opponents increased, also in accordance with sequential assessment. The absolute size of the smaller contestant had no effect on contest duration, in contrast to predictions based on cumulative assessment or energetic war of attrition models. Contestants that lost a fight were more likely to engage immediately in another fight without loss of contest intensity, if their previous fight had been long and intense. This result is inconsistent with contests of endurance, such as the energetic war of attrition or the cumulative assessment game, but it is consistent with the ritualized display of strength and fighting skill. Thus, sequential assessment appears to best explain ritualized fiddler crab contests. Cumulative assessment, however, may be the appropriate model for extended, nonritualized, all-out fights. Cumulative assessment may also explain the tenure of individuals on breeding grounds where multiple engagements are likely to test endurance and tolerance to damage over a period of days. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour. 相似文献
995.
996.
R G Pankov A A Uschewa B T Tasheva P T Petrov G G Markov 《Cell biology international reports》1985,9(11):1003-1011
A dominating protein fraction (p45) having molecular weight of 45000 and pI 5.45 was found in the intermediate filaments pellet obtained from rat liver besides the present cytokeratins. Peptide mapping and radioimmunological assays with antibodies against this protein and muscle actin proved that the p45 protein belongs to the actin group. Immunoelectron microscopy revealed that this protein is located on the liver intermediate filaments. By melting of the cytokeratin complexes in urea it was established that p45 protein is complexed with the low molecular weight cytokeratin. 相似文献
997.
A new aspartic proteinase was isolated from porcine intestine mucosa by affinity chromatography on pepstatin-Sepharose 4B and gel filtration on Sephadex G-100. The enzyme was purified 1600-fold and appeared homogeneous upon polyacrylamide gel electrophoresis. The proteinase has a Mr 60 000 +/- 4000 Da. During sodium dodecyl sulfate polyacrylamide gel electrophoresis the enzyme produced a single protein band (Mr 30 000 +/- 3000 Da). Isoelectric focusing revealed that the enzyme has several multiple forms (pI 6.9, 7.5, 8,0). The enzyme is a glycoprotein containing 5.9% of carbohydrates; the mannose to galactose ratio is 1:3. The amino acid composition of the enzyme was studied. The proteinase splits an oxidized insulin B-chain and synthetic substrates. The pH optimum is 3.2. The enzyme is immunologically identical to porcine spleen cathepsin D. 相似文献
998.
T Kakizono T Nihira H Taguchi 《Biochemical and biophysical research communications》1986,137(3):964-969
Tryptophanase has an essential tyrosyl residue/active site which can be modified by tetranitromethane. Pyridoxal 5'-phosphate can prevent this modification efficiently, whereas pyridoxal 5'-phosphate N-oxide cannot, indicating that the free pyridinium N is required for the interaction of the coenzyme with the tyrosyl residue, probably via a hydrogen bond. The weakened binding of the coenzyme to the modified enzyme was confirmed on gel filtration, the modified enzyme being dissociated from the coenzyme seven-fold faster than the native enzyme. Furthermore, absorption spectral analyses demonstrated that the modified enzyme can catalyze the transaldimination step, but fails to abstract the alpha-H of substrates. The tyrosyl residue, therefore, not only participates in coenzyme binding, but also contributes to alpha-H labilization. 相似文献
999.
S. BLACKMORE C. A. MCCONCHIE R. B. KNOX 《Cladistics : the international journal of the Willi Hennig Society》1987,3(4):333-347
The male program of ontogeny in flowering plants encompasses the events from meiosis of microsporocytes to fertilization. Three main sequences are discussed; the deposition of cell walls, changes in cytoplasmic organelles, and the program of nuclear divisions leading to the formation of two sperm cells and a vegetative cell in each pollen grain. Variations in these ontogenetic sequences are particularly apparent in the monocotyledons, which exhibit diversity in pollen morphology, wall structure, and mode of pollination. The male program of development has been compared in selected terrestrial monocotyledons belonging to the Liliaceae and Gramineae and aquatic members of the Cymodoceaceae, Najadaceae, and Zannichelliaceae. A total of 26 characters from the male program are discussed and then used to construct a cladogram derived only from developmental data for the five species. The polarity of only a few of the character transformations has been determined directly by observation of developmental sequences; most have been interpreted by outgroup analysis. 相似文献
1000.
Synthesis of intrathecal interferon in systemic lupus erythematosus with neurological complications.
Intrathecal synthesis of interferon in the absence of viral or bacterial infection was detected during the occurrence of neurological complications in two patients with systemic lupus erythematosus. The interferons displayed characteristics similar to those observed in the sera of patients with the disease. No interferon inducing activity was detected in the cerebrospinal fluid or serum of the two patients. These observations support the hypothesis of a localised mechanism of interferon induction in systemic lupus erythematosus which includes the interaction of lymphocytes with damaged tissues. 相似文献