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81.
Reindeer calves (n = 632) were slaughtered in November/December (n = 476) or in January (n = 156). Dressed weights and amount of perirenal fat were recorded, and the reproductive organs were collected. A separate group of 130 reindeer calves were weighed at 7 months of age and were followed up with repeated weighings and pregnancy examinations up to 21 months. The onset of puberty and the pregnancy rate were significantly influenced by body weight and the amount of perirenal fat. Approximately 60 g of perirenal fat and 22 kg dressed weight were found at the lower limits for pregnancy. A total of 222 (35%) animals had reached puberty and 126 (20%) were pregnant when examined after slaughter. Animals which conceived during their first autumn showed only a moderate weight gain the following year, and the calf mortality rate in these animals was 47.4%. It was concluded that calf pregnancies are common among the reindeer of Southern Norway and that measures need to be taken to prevent them. 相似文献
82.
Lisbeth B. Møller Jim Kaufman Sten Verland Jan Salomonsen David Avila John D. Lambris Karsten Skjødt 《Immunogenetics》1991,34(2):110-120
Molecular variation among major histocompatibility complex (MHC) class I (B-F) proteins from B-homozygous chickens is apparently caused by C-terminal variation. Analysis of the total B-F protein pool revealed substantial heterogeneity with two or three molecular mass constituents, each being comprised by several isoelectric focusing variants. This heterogeneity could not be reduced by enzymatic deglycosylation. By contrast, proteolytic removal of a small (M
r 1000–4000) fragment from the chain resulted in the generation of a M
r 36 000 fragment, common to all the molecular mass variants. Unlike the parent proteins, the M
r 36 000 fragment derived from isolated variants yielded identical, simple patterns in two-dimensional gel electrophoresis and identical finger prints in peptide mapping. This, together with N-terminal amino acid sequencing, as well as comparison of hydrophobicity properties of fragments obtained by gradual proteolytic digestion, indicated that the small peptide responsible for the major B-F heterogeneity was situated in the intracellular, C-terminal part. 相似文献
83.
High-affinity binding of3H-folate in Triton X-100 solubilized membranes of human liver displayed characteristics, e.g. apparent positive cooperativity, which are typical of specific folate binding. Ultrogel® AcA 44 chromatography of solubilized membranes saturated with3H-folate revealed a major peak of 100 kDa and a minor peak of 25 kDa. The 100 kDa peak could represent a hydrophobic membrane associated molecular form of the protein. This notion was supported by the fact that the two peaks had identical molecular weights as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis with immunoblotting. 相似文献
84.
Jørgen Clausen 《Biological trace element research》1991,28(1):39-45
Polyunsaturated fatty acids (PUFAs) occur in relatively high amounts in phospholipids of the synapses. PUFAs may thus determine the fluidity of the synaptosomal membrane and, hereby, they may regulate the neuronal transmission. It was therefore tempting to suggest a system in the brain, that inhibits autooxidation of PUFAs. In order to trace such a protection system, Wistar rats were equally loaded with 4500 kBq of 75-Se either as selenite or as L-Se-methionine. By means of gradient ultracentrifugation, particulate fractions of the brains were isolated, and the radioactivity as well as the glutathione-transferase and -peroxidase activities were estimated. The distribution of the two selenium components among the particulate fractions was different. Thus, selenite gave higher radioactivity in myelin, then followed by the light synaptosomal and the vesicular fraction. L-Se-methionine was more equally incorporated in all particulate fractions, although highest activity was found in the mitochondrial fraction. Myelin and synaptic vesicles were devoid of transferase activity. On the other hand, the synaptosomal fraction showed highest specific transferase activity. The glutathione peroxidase activity was highest in the myelin fraction, followed by the vesicular and the synaptosomal fractions. The data obtained thus support the idea that the PUFAs of the synaptic compartment are protected against peroxidation, at least in part, by the selenium containing glutathione peroxidase. 相似文献
85.
Merete Grung Frances M. L. D'Souza Michael Borowitzka Synnøve Liaaen-Jensen 《Journal of applied phycology》1992,4(2):165-171
Aplanospores ofHaematococcus pluvialis MUR 145 contained 0.7% carotenoids (dry wt. basis) consisting of β,β-carotene (5% of total carotenoid), echinenone (4%),
canthaxanthin (4%), (3S,3′S)-astaxanthin diester (34%), (3S,3′S)-astaxanthin monoester (46%), (3S,3′S)-astaxanthin (1%) and (3R,3′R,6′R)-lutein (6%).
The astaxanthin esters were examined by TLC and HPLC and VIS,1H NMR and mass spectra recorded. Their chirality was determined by the camphanate method (Vecchi & Müller, 1979) after anaerobic
hydrolysis.
The tough cell wall of the aplanospores required enzymatic treatment prior to pigment extraction. The potential use of this
microalga as a feed ingredient in aquaculture is discussed briefly. 相似文献
86.
A leptomycin B resistance gene of Schizosaccharomyces pombe encodes a protein similar to the mammalian P-glycoproteins 总被引:4,自引:0,他引:4
Kazunori Nishi Minoru Yoshida Marie Nishimura Mitsuo Nishikawa Makoto Nishiyama Sueharu Horinouchi Teruhiko Beppu 《Molecular microbiology》1992,6(6):761-769
Screening for leptomycin B (LMB)-resistant transformants in a gene library constructed in Schizosaccharomyces pombe with the chromosomal DNA of an LMB-resistant mutant of S. pombe and with multicopy plasmid pDB248' as the vector led to the isolation of a gene, named pmd1+, encoding a 1362-amino-acid protein. This protein showed great similarity in amino acid sequence to the mammalian P-glycoprotein encoded by the multidrug resistance gene, mdr, and the Saccharomyces cerevisiae a-factor transporter encoded by STE6. In addition, computer analyses predicted that the protein encoded by pmd1+ formed an intramolecular duplicated structure and each of the halves contained six transmembrane regions as well as two ATP-binding domains, as observed with the P-glycoproteins and the STE6 product. Consistent with this was that S. pombe cells containing the pmd1+ gene on a multicopy plasmid showed resistance not only to LMB but also to several cytotoxic agents. The pmd1 null mutants derived by gene disruption were viable and hypersensitive to these agents. All these data suggest that the pmd1+ gene encodes a protein that is a structural and functional counterpart of mammalian mdr proteins. 相似文献
87.
Johan B. Steen Øivind Tøien Peder Fiske 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(2):155-158
1. | Physiological adaptation to hypothermia were studied in newly hatched great snipe chicks (Gallinago media) by measuring oxygen uptake (VO2), heart rate (HR), respiratory frequency (RF), and body temperature (Tb) at different ambient temperatures (Ta). |
2. | Tb of 1-day-old chicks at Ta of 35°C stabilized at about 40°C. At Ta between 20 and 30°C the chicks maintained a Tb about 8°C above Ta. Hatchlings maintained a higher gradient when active than when resting. Below 20°C they were unable to maintain a stable Tb. |
3. | In resting hatchlings VO2 was similar at Ta between 35 and 20°C (Tb 40–30°C), VO2 range 1.7–2.5 ml·g-1·h-1. Below 20°C, VO2 declined with time. |
4. | The HR of 1-day-old chicks fell linearly with Tb during cooling. The Q10 of the HR was 1.7 at Tb 38°C and increased to 3.0 at 29°C. The RF showed a slight tendency to decrease with decreasing Tb. |
5. | It is concluded that the ability to maintain normal dexterity at low Tb is an important aspect of snipe survival strategy. Maintaining a temperature gradient rather than a constant high Tb presumably saves energy. It is suggested that the mechanisms whereby VO2 is maintained at a low Tb may involve isoenzymes and adaptations of the nervous system. However, such adaptations would not seem to affect the pacemaker mechanism as evidenced by the high Q10 of the HR. |
88.
René Roy François D. Tropper Anna Romanowska Marie Letellier Luc Cousineau Serge J. Meunier Janusz Boratyński 《Glycoconjugate journal》1991,8(2):75-81
Starting from peracetylated chloro- or bromo-glycosyl donors ofN-acetylneurmainic acid,N-acetylglucosamine, glucose and lactose, the correspondingp-formylphenyl glycosides were synthesized stereospecifically under phase transfer catalysed conditions at room temperature in yields of 38–67%. After Zemplén de-O-acetylation, the formyl groups were directly and chemoselectively coupled to the lysine residues of bovine serum albumin by reductive amination using sodium cyanoborohydride. The conjugation reactions were followed as a function of time and under a series of different molar ratios of the reactants to provide glycoconjugates of varying degree of antigenicities. Thus, carbohydrate protein conjugates were made readily available using essentially two key reactions.Presented in part at the 15th International Carbohydrate Symposium, Yokohama, Japan, August 12–17, 1990. 相似文献
89.
90.
Gabi Wegmann Regula Huber Else Zanolla Hans M. Eppenberger Theo Wallimann 《Differentiation; research in biological diversity》1991,46(2):77-87
The expression and the cellular- as well as subcellular-distribution of brain-type B-CK and mitochondrial Mi-CK during development of the chicken retina was studied by immunoblotting, immunofluorescence and immunogold methods. B-CK expression and accumulation in retina was high from early stages of embryonic development on, decreased slightly around hatching and remained high again during adulthood. At early stages of development (days 2-5), B-CK was more or less evenly distributed over the entire retina with the exception of ganglion cells, which were stained more strongly for B-CK than other retinal precursor cells. Then, at around day 10, the beginning of stratified immunostaining by anti-B-CK antibody was noted concomitant with progressing differentiation. Finally, a dramatic increase in staining of the differentiating photoreceptor cells was seen before hatching (day 18) with weaker staining of other cell types. At hatching, as in the adult state, most of the B-CK was localized within rods and cones. Thus, during retinal development marked changes in the immunostaining pattern for B-CK were evident. By contrast, Mi-CK expression was low during development in ovo and rose just before hatching with a predominant accumulation of this isoenzyme within the ellipsoid portion of the inner photoreceptor cell segments. Mi-CK accumulation in the retina coincided with functional maturation of photoreceptors and therefore represents a good marker for terminal differentiation of these cells. B-CK, present from early stages of retina development, seems to be relevant for the energetics of retinal cell proliferation, migration and differentiation, whereas the simultaneous expression of both B- and Mi-CK around the time of hatching indicates a coordinated function of the two CK isoforms as constituents of a PCr-circuit involved in the energetics of vision, which, in autophagous birds, has to be operational at this point in time. 相似文献