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121.
J. D. Penschow Michelle E. Giles John P. Coghlan R. T. Fernley 《Histochemistry and cell biology》1997,107(5):417-422
Carbonic anhydrase VI (CA VI) is a secreted enzyme produced predominantly by serous acinar cells of submandibular and parotid
glands. We have investigated the developmental pattern of CA VI production by these glands in the sheep, from fetal life to
adulthood, using immunohistochemistry. Also, a specific radioimmunoassay for CA VI was used to measure changes in enzyme expression
in the parotid gland postnatally. CA VI is detectable by immunohistochemistry in parotid excretory ducts from 106 days gestation
(term is 145 days), in striated ducts from 138 days and in acinar cells from 1 day postnatal. The duct cell content of CA
VI declined as the acinar cell population increased, a feature also of CA VI immunoreactivity in the submandibular gland.
Production of CA VI by submandibular duct cells was detectable initially at 125 days gestation, and acinar production was
not seen before 29 days post-natal. Apart from the differing ontogeny of CA VI production in ducts and acini of parotid and
submandibular glands, there was a parallel pattern of CA VI expression during the development of these major salivary glands.With
the development of the acinar tissues in the postnatal lamb, there was a dramatic increase (about 600-fold) in the level of
expression of CA VI in the parotid gland between days 7 and 59 as measured by radioimmunoassay.
Accepted: 19 December 1996 相似文献
122.
Expression of Bcl-2 protein in the epiphyseal plate cartilage and trabecular bone of growing rats 总被引:2,自引:0,他引:2
Ying Wang Renée Toury Michelle Hauchecorne N. Balmain 《Histochemistry and cell biology》1997,108(1):45-55
The protooncogene protein, Bcl-2, protects cells from apoptosis and ensures their survival in vitro by inhibiting the action
of the apoptosis-inducer, Bax. Its expression in proliferative and long-lived cells in vivo also indicates that it protects
against cell death. The chondrocytes of the epiphyseal plate cartilage undergo a series of maturation steps and deposit mineral
in the cartilage matrix before dying. The possibility that Bcl-2 helps protect chondrocytes until mineral deposition is completed
was investigated by determining the distribution of Bcl-2 immunoreactivity in the epiphyseal plate cartilage of growing rats
and its subcellular localization, using a specific antibody. The involvement of Bax in the triggering of chondrocyte death
was checked by immunocytochemistry. Bcl-2 expression in the osteoblasts and the final result of their evolution, the osteocytes,
was also examined in trabecular bone. Bcl-2 immunoreactivity was non-uniformly distributed throughout the epiphyseal cartilage.
It was maximal in proliferative chondrocytes, decreased in mature chondrocytes, and low in hypertrophic chondrocytes, whereas
there was Bax immunoreactivity in all chondrocytes examined. Immunolabeling was intense in osteoblasts but considerably lower
in fully differentiated osteocytes. Bcl-2 immunoreactivity was mainly in the cytoplasm of chondrocytes, osteoblasts, and early
osteocytes; the nuclei appeared clear. The subcellular distribution of Bcl-2 immunolabeling in chondrocytes, revealed by gold
particles in the electron microscope, showed that gold particles were frequently concentrated in the mitochondria in all the
cartilage zones and lay mainly within the organelles, not at their periphery. The endoplasmic reticulum contained moderate
immunoreactivity and there were few gold particles in the cytoplasm and nuclei. The number of gold particles decreased in
all the subcellular compartments from proliferative to hypertrophic chondrocytes. In contrast, Bax immunoreactivity changed
little during chondrocyte terminal evolution, and its subcellular distribution mirrored that of Bcl-2. These immunocytochemical
data indicate that Bcl-2 helps maintain chondrocytes and osteoblasts until their terminal maturation.
Accepted: 19 February 1997 相似文献
123.
Ecological correlates of hind-limb length in the Carnivora 总被引:1,自引:0,他引:1
What determines the lengths and proportions of mammalian limbs? While the answer to this question is still largely unknown, a number of workers have recently begun analysing the selection of morphology in a rigorous framework, searching for quantitative links between structure, performance, and their ecological and behavioural context. The present study investigates a variety of ecological and behavioural variables to determine whether or not they are correlated with hind-limb length in the Carnivora. Data were analysed by using phylogenetically independent contrasts and phylogenetic analysis of covariance. We found that traditional perceptions of limb length are often inaccurate; some species widely regarded as relatively long-legged actually have limb lengths near those expected for their body size. Interestingly, relative hind-limb length is not a significant predictor of distance moved daily, home-range area, or prey size. Phylogenetic ANCOVA results, however, indicate a relationship between prey-capture behaviour and relative hind-limb length. These findings suggest that the evolution of carnivoran limb length has been most influenced by selection for prey-capture behaviour. These results, coupled with those of other studies, can be used to suggest which performance variables could most fruitfully be studied in the laboratory to understand the selection of the structure of the mammalian limb. We suggest that relevant performance variables might be: maximum jump height and/or length, the ability to generate outforces, and levels of stress tolerance in limb bones during prey pursuit/capture. 相似文献
124.
125.
Ann-Charlotte E. Granholm Michelle L. Price Michael D. Owen 《Cell and tissue research》1995,280(1):49-57
We have investigated the distribution of tyrosine-hydroxylase-like immunoreactivity in the cerebral ganglia of the American cockroach, Periplaneta americana. Groups of tyrosine-hydroxylase-immunoreactive cell bodies occur in various parts of the three regions of the cerebral ganglia. In the protocerebrum, single large neurons or small groups of neurons are located in the lateral neuropil, adjacent to the calyces, and in the dorsal portion of the pars intercerebralis. Small scattered cell bodies are found in the outer layers of the optic lobe, and clusters of larger cell bodies can be found in the deutocerebrum, medial and lateral to the antennal glomeruli. Thick bundles of tyrosine-hydroxylase-positive nerve fibers traverse the neuropil in the proto- and deutocerebrum and innervate the glomerular and the nonglomerular neuropil with fine varicose terminals. Dense terminal patterns are present in the medulla and lobula of the optic lobe, the pars intercerebralis, the medial tritocerebrum, and the area surrounding the antennal glomeruli, the central body and the mushroom bodies. The pattern of tyrosine-hydroxylase-like immunoreactivity is similar to that previously described for catecholaminergic neurons, but it is distinctly different from the distribution of histaminergic and serotonergic neurons. 相似文献
126.
Addi R. Fadel Dan Q. Jin Gaetano T. Montelione Ronald M. Levy 《Journal of biomolecular NMR》1995,6(2):221-226
Summary Order parameters for the backbone N–H and C–H bond vectors have been calculated from a 150 ps molecular dynamics (MD) simulation of human type- transforming growth factor in H2O solvent. Two kinds of crankshaft motions of the polypeptide backbone are observed in this MD trajectory. The first involves small-amplitude rocking of the rigid peptide bond due to correlated changes in the backbone dihedral angles i–1 and i. These high-frequency librational crankshaft motions are correlated with systematically smaller values of motional order parameters for backbone N–H bond vectors compared to C–H bond vectors. In addition, infrequent crankshaft flips of the peptide bond from one local minimum to another are observed for several amino acid residues. These MD simulations demonstrate that comparisons of N–H and C–H order parameters provide a useful approach for identifying crank-shaft librational motions in proteins. 相似文献
127.
本文报道了采自贵州沿河土地坳下奥陶统的牙形石,计有25属39种,根据牙形石组合特片分析,认为其与黔北其它地区下奥陶统牙形石组合面貌基本一致,属北大西洋牙形石动物地理区。 相似文献
128.
鱼腥藻HB1017株化能异养生长的研究 总被引:5,自引:1,他引:4
以葡萄糖和蔗糖为碳源,检测了六株(种)鱼腥藻的化能异养生产能力。其中鱼腥藻HB1017株化能异养生长较快,鱼腥藻HB0株化能异养生长缓慢,其余四种鱼腥藻不能进行化能异养生长。鱼腥藻HB1017株能利用果糖、葡萄糖、蔗糖为底物进行化能异养生长,但生长速率依次递减,差别显著。8磅湿热灭菌的果糖和蔗糖,与过滤灭菌的相比,只能维持低得多的化能异养生长速率。然而,8磅湿热灭菌的葡萄糖能维持比过滤法灭菌的高得 相似文献
129.
生态环境对白芷产量质量的影响 总被引:1,自引:0,他引:1
生态环境对白芷产量质量的影响陈兴福,丁德蓉,刘岁荣,卢进,黄文秀(四川省中医药研究院药物种植研究所,南川648408)EffectofEco-EnvironmentonDahurianAngelicaYieldandItsQuality¥ChenXi... 相似文献
130.