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71.
72.
Background
Twenty years ago this year was the first publication describing a region of neural crest cells necessary for normal cardiovascular development. Ablation of this region in chick resulted in persistent truncus arteriosus, mispatterning of the great vessels, outflow malalignments, and hypoplasia or aplasia of the pharyngeal glands.Methods
We begin with a historical perspective and then review the progress that has been made in the ensuing 20 years in determining the direct and indirect contributions of the neural crest cells, now termed cardiac neural crest cells, in cardiovascular and pharyngeal arch development. Many of the molecular pathways that are now known to influence the specification, migration, patterning and final targeting of the cardiac neural crest cells are also reviewed.Results
Although much knowledge has been gained by using many genetic manipulations to understand the cardiac neural crest cells' role in cardiovascular development, most models fail to explain the phenotypes seen in syndromic and non‐syndromic human congenital heart defects, such as the DiGeorge syndrome.Conclusions
We propose that the cardiac neural crest exists as part of a larger cardiocraniofacial morphogenetic field and describe several human syndromes that result from abnormal development of this field. Birth Defects Research (Part C) 69:2–13, 2003. © 2003 Wiley‐Liss, Inc.73.
Jeff Kirby 《Biology & philosophy》2003,18(5):683-694
Abstract. Scientists have long puzzled over how homosexual orientation has evolved, given the assumed low relative fitness of homosexual individuals compared to heterosexual individuals. A number of theoretical models for the evolution of homosexuality have been postulated including balance polymorphism, "Fertile females", hypervariability of DNA sequences, kin selection, and "parental manipulation". In this paper, I propose a new group-selection model for the evolution of homosexuality which offers two advantages over existing models: (1) its non-assumption of genetic determinism, and (2) its lack of dependency on an inefficient altruism relation and family dynamics theory. 相似文献
74.
Yokoyama Y Toth B Kitchens WC Schwacha MG Bland KI Chaudry IH 《American journal of physiology. Gastrointestinal and liver physiology》2003,285(6):G1293-G1299
Thromboxane A2 (TXA2) and endothelin-1 (ET-1) have been proposed as the important vasoconstrictors that increase portal venous resistance in paracrine or autocrine fashion. We hypothesized that the hepatic damage following trauma-hemorrhage (T-H) is induced by the impaired hepatic circulation due to the increased production of vasoconstrictors such as ET-1 and TXA2 by the liver. To test this, male Sprague-Dawley rats (n = 6/group) were subjected to trauma (i.e., midline laparotomy) and hemorrhage (35-40 mmHg for 90 min followed by fluid resuscitation) or sham operation. At 2 or 5 h after the end of resuscitation, the liver was isolated and perfused and portal inflow pressure, bile flow, and release of ET-1 and thromboxane B2 (TXB2; a stable metabolite of TXA2) into the perfusate were measured. The level of portal pressure was higher at 5 h following T-H compared with 2 h after T-H and sham. The portal pressure was inversely correlated to the amount of bile production. Furthermore, the bile flow was significantly correlated to the hepatic damage as evidenced by release of lactate dehydrogenase into the perfusate. The level of ET-1 at 5 h following T-H in the perfusate after 30 min of recirculation did not show any difference from sham. However, the levels of TXB2 in the T-H group were significantly higher than those in sham at that interval. These results indicate that the increased release of TXA2 but not ET-1 following T-H might be responsible for producing the increased portal resistance, decreased bile production, and hepatic damage. 相似文献
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76.
Microbial decolourisation and degradation of textile dyes 总被引:33,自引:0,他引:33
McMullan G Meehan C Conneely A Kirby N Robinson T Nigam P Banat IM Marchant R Smyth WF 《Applied microbiology and biotechnology》2001,56(1-2):81-87
Dyes and dyestuffs find use in a wide range of industries but are of primary importance to textile manufacturing. Wastewater from the textile industry can contain a variety of polluting substances including dyes. Increasingly, environmental legislation is being imposed to control the release of dyes, in particular azo-based compounds, into the environment. The ability of microorganisms to decolourise and metabolise dyes has long been known, and the use of bioremediation based technologies for treating textile wastewater has attracted interest. Within this review, we investigate the mechanisms by which diverse categories of microorganisms, such as the white-rot fungi and anaerobic bacterial consortia, bring about the degradation of dyestuffs. 相似文献
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78.
Simultaneous measurements of plasma LH, body temperature, and locomotor activity were made in laying turkey hens and are reported. Blood samples were remotely collected using a jugular cannula system, and body temperature and locomotor activity were remotely monitored using a radiotelemetry system in freely moving laying turkeys. Under a photoschedule of 14L:10D, the period for preovulatory surges of LH was 25.7 +/- 0.4 h while the periods for peak body temperature and onset of sustained locomotor activity were 24.9 +/- 0.4 and 25.7 +/- 0.5 h, respectively. During exposure to constant light, the periods for preovulatory surges of LH, peak body temperature, and onset of sustained locomotor activity increased to 27.9 +/- 0.9, 26.7 +/- 0.7, and 27.4 +/- 0.7 h, respectively. With the 14L:10D photoschedule, initiation of LH surges was restricted to the scotophase, but after 8 days of constant light, initiation of LH surges had dispersed throughout the 24-h subjective day and night. With constant light, the amplitude of the peak body temperature rhythm decreased, while the duration of the locomotor activity rhythm became broadened and, in some birds, disorganized. Peak body temperature and onset of locomotor activity rhythms and LH surges did not coincide, even though peak body temperature, onset of locomotor activity, and LH surges had similar periods. It is concluded that 1) the photoschedule influences the periods of the LH surge, peak body temperature, and onset of locomotor activity; and 2) a specific or direct relationship between the rhythms of LH surge, body temperature, and locomotor activity remains to be determined in laying turkey hens. 相似文献
79.
The adhesion molecule lymphocyte function-associated antigen 3 (LFA-3) (CD58) is an important regulator of immune cell function which occurs as both surface-associated and 'soluble' forms. This study has investigated the inter-relationship and the effects of cytokines on the expression of LFA-3 isoforms. The surface antigen was found to be relatively unaffected by cytokines, but the release of soluble LFA-3 (sLFA-3) was highly responsive to interleukin 1beta (IL-1beta), interferon gamma (IFN-gamma) and tumour necrosis factor alpha (TNF-alpha). This modulation was cell-specific, particularly with regard to IFN-gamma, which up-regulated sLFA-3 release by A431 cells but down-regulated the release of the soluble form from HEp2 and HepG2 cells. We further demonstrated that LFA-3 is also present in a cytoplasmic 'pool' in each of the cells and, moreover, that cleavage of LFA-3 from the cell surface by phospholipase C resulted in an increase in the levels of the intracellular LFA-3 and replacement of the membrane-associated antigen. These observations suggest that the expression of the surface, soluble and intracellular forms of LFA-3 may be linked by regulatory mechanisms which are likely to exert an important influence on inflammatory interactions. 相似文献
80.
Decolourisation of synthetic textile dyes by Phlebia tremellosa 总被引:4,自引:0,他引:4
Phlebia tremellosa decolourised eight synthetic textile dyes (200 mg l(-1)) by greater than 96% within 14 days under stationary incubation conditions. High performance liquid chromatography analysis of culture supernatants indicated that Remazol Black B was degraded by the fungus, however, complete mineralisation did not occur as a colourless organic breakdown product accumulated. Laccase activity was detectable in culture supernatants after 5 days when the fungus was grown in the presence of an artificial textile effluent, with activity reaching a maximum of 15 U l(-1) on day 14. 相似文献