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71.
72.
The Notch pathway contributes to self-renewal of tumor-initiating cell and inhibition of normal colonic epithelial cell differentiation. Deregulated expression of Notch1 and Jagged1 is observed in colorectal cancer. Hairy/enhancer of split (HES) family, the most characterized targets of Notch, involved in the development of many cancers. In this study, we explored the role of Hes1 in the tumorigenesis of colorectal cancer. Knocking down Hes1 induced CRC cell senescence and decreased the invasion ability, whereas over-expression of Hes1 increased STAT3 phosphorylation activity and up-regulated MMP14 protein level. We further explored the expression of Hes1 in human colorectal cancer and found high Hes1 mRNA expression is associated with poor prognosis in CRC patients. These findings suggest that Hes1 regulates the invasion ability through the STAT3-MMP14 pathway in CRC cells and high Hes1 expression is a predictor of poor prognosis of CRC.  相似文献   
73.
Pseudanisakis sulamericana n. sp. is described from the intestines of the rays Rioraja agassizii and Psammobatis extenta off the coast of Brazil. It can be readily differentiated from the three existing species of the genus. From P. tricupola Gibson, 1973, it differs in not having cupolas on the lips, having a dentigerous ridge of 90-95 denticles ( vs 65-78) in a continuous subtriangular ring around the mouth, and in having an ejaculatory duct which is shorter than the spicules. From P. rajae (Yamaguti, 1941), it differs in having a single rather than a double row of denticles. It appears most similar to P. baylisi Gibson, 1973, but differs from it in having a smaller body-size (7.5-27 vs 16-46 mm), shorter spicules (1.14-1.90 vs 1.90-3.80 mm) and especially in having much more conspicuous denticles on the lips. The present record confirms the presence of the genus in subtropical waters.  相似文献   
74.
75.
The neurite outgrowth and adhesion complex (NOAC), isolated from rabbit sera has been dissociated in its major components by reverse-phase chromatography in HPLC by using a C18 column. SDS-PAGE analisys of the active fractions revealed the presence of three major bands of approximately 100, 70 and 50 kDa. Studies on the biological activity of NOAC were carried out on rat cerebellar granule cells. NOAC-cultured cells exhibit a marked resistance to excitotoxic stimuli carried by glutamate.  相似文献   
76.
Data-base searches of records of the helminth parasites of South American and African freshwater fishes revealed only two pairs of species from genera endemic to the two regions. One pair, species of the primitive amphilinid cestode genus Nesolecithus Dönges &; Harder, 1966, has already been designated as likely Gondwana relicts. The second pair are the philometrid nematodes Nilonema gymnarchi Khalil, 1960 from Gymnarchus niloticus Cuvier (Gymnarchidae) in Africa and N. senticosum (Baylis, 1922) from the South American fish Arapaima gigas (Cuvier) (Arapaimidae). Both species are partly redescribed on the basis of light and scanning electron microscopical observations of the type-specimens, and their relationships are discussed. In view of the fact that both hosts are basal teleosts of the order Osteoglossiformes and they are the same two fish which harbour the amphilinid cestodes already indicated as Gondwana relics, the nematode pair is also deemed to be relictual. However, these species are suggested as being of limited potential value for calibrating a molecular clock.  相似文献   
77.
Molecular evolution of chloroplast DNA sequences   总被引:12,自引:1,他引:12  
Comparative data on the evolution of chloroplast genes are reviewed. The chloroplast genome has maintained a similar structural organization over most plant taxa so far examined. Comparisons of nucleotide sequence divergence among chloroplast genes reveals marked similarity across the plant kingdom and beyond to the cyanobacteria (blue-green algae). Estimates of rates of nucleotide substitution indicate a synonymous rate of 1.1 x 10(-9) substitutions per site per year. Noncoding regions also appear to be constrained in their evolution, although addition/deletion events are common. There have also been evolutionary changes in the distribution of introns in chloroplast encoded genes. Relative to mammalian mitochondrial DNA, the chloroplast genome evolves at a conservative rate.   相似文献   
78.

Background  

In many areas of medical research, a bivariate analysis is desirable because it simultaneously tests two response variables that are of equal interest and importance in two populations. Several parametric and nonparametric bivariate procedures are available for the location problem but each of them requires a series of stringent assumptions such as specific distribution, affine-invariance or elliptical symmetry.  相似文献   
79.
The preceding set of articles is reviewed with a focus on the forces affecting the rise and character of grass-roots transnationalism and its effects in countries of origin and destination. The increasing visibility of the phenomenon has led to recent attacks based on its alleged disintegrative consequences for the host society and culture. From a review of the evidence in this volume and the recent literature on immigrant adaptation, I conclude that the opposite is the case. Implications of findings presented in this collection for official policies towards transnationalism and the latter's effect on sending countries are examined.  相似文献   
80.
A new genus and species of monogenean belonging to Hexabothriidae, Hypanocotyle bullardi n. gen. n. sp., is described based on specimens collected from the gill filaments of the diamond stingray, Hypanus dipterurus (Jordan et Gilbert) (Myliobatiformes: Dasyatidae), a demersal chondrichthyan collected off the coast of Callao, Peru. Hypanocotyle n. gen. has the following combination of diagnostic features that differentiate it from other hexabothriid genera: haptor symmetrical; vasa efferentia having proximal (narrow, with thin glandular wall) and distal (expanded, interlaced, with thick glandular wall) portions, joining medially to form vas deferens; vas deferens having proximal (expanded, sinuous, with thick glandular wall) and distal (narrow, strongly sinuous, with thin glandular wall) portions; male copulatory organ unarmed, proximal portion slightly sinuous and tube-like, distal portion funnel-shaped; prostatic glands present, distributed around of the MCO; seminal receptacle present; ootype lacking longitudinal rows of large cells (no oötype côtelé); vaginae parallel, with well-differentiated proximal (glandular, narrow, tube-like, slightly sinuous) and distal (musculoglandular, convoluted) portions; gland cells surrounding the vaginal duct along the entire length of distal portion, densely clustered in middle portion; uterine eggs with 2 elongate filaments. Phylogenetic reconstructions by maximum-likelihood method, based on newly obtained partial 18S and 28S sequences, shows that H. bullardi n. gen. is included within the family Hexabothriidae, order Diclybothriidea. This is the second hexabothriid genus recorded from a diamond stingray (Dasyatidae), and the fourth hexabothriid species recorded from Peru. A key to hexabothriid genera is provided.  相似文献   
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