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71.
SYNOPSIS. The fine structure of schizonts and free merozoites of the neogregarine Farinocystis tribolii Weiser, and their development in the fat body of larval Tribolium castaneum were studied.
The surface of a multinucleate schizont and that of a uninucleate merozoite is covered by a double-layered membrane. Rhoptries and micronemes are present. The cytoplasm is packed with ribosomes and also contains dark bodies. Mitochondria are of the vesicular type. The spherical nucleus of the schizont and merozoite contains a large nucleolus. The anterior end of the merozoite has a typical conoidal complex composed of a conoid and a polar ring with 22 subpellicular mirotubules projecting from it.
New findings are a membranous septum across the body of the merozoite at 2/3 of its length below the nucleus and a highly osmiophilic spiral structure in the perinuclear space close to the Golgi complex. In addition, we found some "developmental stages" of the latter structure.  相似文献   
72.
Using two sets of nucleotide sequences of the human and simian T-cell leukemia/lymphoma virus type I (HTLV-I/STLV-I), one consisting of 522 bp of the env gene from 70 viral strains and the other a 140-bp segment from the pol gene of 52 viral strains, I estimated cladograms based on a statistical parsimony procedure that was developed specifically to estimate within-species gene trees. An extension of a nesting procedure is offered for sequence data that forms nested clades used in hypothesis testing. The nested clades were used to test three hypotheses relating to transmission of HTLV/STLV sequences: (1) Have cross-species transmissions occurred and, if so, how many? (2) In what direction have they occurred? (3) What are the geographic relationships of these transmission events? The analyses support a range of 11-16 cross-species transmissions throughout the history of these sequences. Additionally, outgroup weights were assigned to haplotypes using arguments from coalescence theory to infer directionality of transmission events. Conclusions on geographic origins of transmission events and particular viral strains are inconclusive due to small samples and inadequate sampling design. Finally, this approach is compared directly to results obtained from a traditional maximum parsimony approach and found to be superior at establishing relationships and identifying instances of transmission.   相似文献   
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按Bishop方法,在小鼠血液里诱导生成大量网织红细胞,然后提取网织红细胞,对其电泳率、渗透脆性、膜的流动性、细胞的变形能力和取向性进行了系统研究。研究结果表明网织红细胞在转变为成熟红细胞的短短时间内,其微观流变学特性发生了明显的变化:电泳率变小、渗透脆性变好、膜的流动性变大、细胞的变形能力变强、取向性变好,最终发育成具有全面功能的成熟红细胞。  相似文献   
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Abstract

The palatability to common carp, Cyprinus carpio L. of three newly developed differently flavoured floating pellets made from a high proportion (40%) of brewer's spent grain (BSG) was tested using a multiple-offer feeding experiment. The addition of ‘bold’ flavours, such as vanilla or strawberry essence, may help mask the unpleasant taste of some piscicides; however, their inclusion must not compromise uptake by carp. There were no significant differences between the consumption rates of the three varieties, and all flavours were readily consumed. Therefore, it is suggested that highly flavoured pellets made with BSG have a strong potential to mask the flavour of an unpalatable toxin, and further research is now needed to test this hypothesis.  相似文献   
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