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Summary

The male reproductive tract of Scyllarus chacei consists of paired testes and vasa deferentia that conduct sperm containing spermatophores to the genital pores at the base of each fifth walking leg. The testis is joined to the vas deferens which can be divided into four regions: (1) the anterior vas deferens can be further divided into three regions. It is highly convoluted and is the region in which the sperm become encapsulated in ovoid spermatophores of approximately 100 sperm as well as produces seminal fluids. (2) The middle vas deferens is the primary site of sperm storage and adds to seminal fluids which formed in the anterior region. (3) The posterior region is highly muscularized and may serve for limited sperm storage. (4) The most distal portion is the ejaculatory duct which is highly muscularized for extruding the spermatophoric mass for transfer to the female. A final seminar product is added here.  相似文献   
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HIV is a persistent virus that survives and replicates despite an onslaught by the host's immune system. A strategy for cell entry, requiring the use of two receptors, has evolved that may help evade neutralizing antibodies. HIV and SIV usually require both CD4 and a seven transmembrane (7TM) coreceptor for infection. At least eleven different 7TM coreceptors have been identified that confer HIV and/ or SIV entry. For HIV-1, the major coreceptors are CCR5 and CXCR4, while the role of other coreceptors for replication and cell tropism in vivo is currently unclear. Polymorphisms in the CCR5 gene that reduce CCR5 expression levels, protect against disease progression, suggesting that drugs targeted to CCR5 could be effective. Such therapies however will not work if HIV simply adapts to use alternative coreceptors. In the light of these themes, this review will discuss the following topics: (i) the coreceptors used by primary HIV-1 and HIV-2 viruses, (ii) the properties and coreceptors of HIV-2 strains that infect cells without CD4, (iii) the role of coreceptors in HIV cell tropism and particularly macrophage infection and (iv) the properties of chemokine receptor ligands that block HIV infection.  相似文献   
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Amplification of immunohistochemical markers received considerable attention during the 1980s and 1990s. The amplification approach was largely abandoned following the development of antigen retrieval and reporter amplification techniques, because the latter were incorporated more easily into high throughput automated procedures in industrial and diagnostic laboratories. There remain, however, a number of instances where marker amplification still has much to offer. Consequently, we examined experimentally the utility of an optimized marker amplification technique in diagnostically relevant tissue where either the original signal strength was low or positive sites were visible, but sparsely distributed. Marker amplification in the former case not only improved the visibility of existing positive sites, but also revealed additional sites that previously were undetectable. In the latter case, positive sites were rendered more intense and therefore more easily seen during low magnification examination of large areas of tissue.  相似文献   
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A number of in vitro studies suggest that many important developmental and functional events in the enteric nervous system are regulated by the intracellular signaling enzyme cAMP protein kinase A (PKA). To evaluate the in vivo significance of these observations, a Cre‐inducible, dominant‐negative, mutant regulatory subunit (RIαB) of PKA was activated in enteric neurons by either a Proteolipid protein‐Cre transgene or a Hox11L1‐Cre “knock‐in” allele. In both models, RIαB activation resulted consistently in profound distension of the proximal small intestine within 2 weeks after birth. Intestinal transit of radio‐opaque tracers was severely retarded in the double‐transgenic animals, which died shortly after weaning. In the enteric nervous system, recombination was restricted to neurons as demonstrated by histochemical analysis and confocal microscopic colocalization of a Cre recombinase‐dependent reporter gene with the neuronal marker Hu(C/D), in contrast with the glial marker S100. Histochemical analysis of β‐galactosidase expression and acetylcholinesterase activity, as well as neuronal counts, demonstrated that intestinal dysmotility was not associated with obvious malformation of the myenteric plexus. However, inhibition of PKA activity in enteric neurons disrupted the major motor complexes of isolated intestinal segments in vitro. These results provide strong evidence that PKA activity plays a critical role in enteric neurotransmission in vivo, and highlight neuronal PKA or related signaling molecules as potential therapeutic targets in gastrointestinal motility disorders. © 2005 Wiley Periodicals, Inc. J Neurobiol, 2006  相似文献   
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