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1.
G. K. Innes B. J. Fuller K. E. F. Hobbs 《In vitro cellular & developmental biology. Plant》1988,24(2):126-132
Summary Rat hepatocytes were isolated and then maintained in serum-free cell culture medium for 24 h. The amount of malondialdehyde
(MDA) accumulated in the medium was assayed and used as a measure of lipid peroxidation. The acivity of lactate dehydrogenase
(LDH) and urea were measured in the medium and used as indicators of hepatocellular viability and function. The effects of
iron; desferrioxamine mesylate (Desferal), an iron chelator; and mannitol, a hydroxyl free radical scavenger were investigated.
The addition of iron, Fe2 resulted in a three-fold increase in the levels of MDA. Desferal inhibited the production of MDA and blocked the effect of
Fe2+. Neither iron nor Desferal had any effect on LDH or urea levels. Mannitol had no effect on MDA or urea production, but caused
a 4 to 8-fold increase in the LDH levels in the medium. The results show that iron is involved in the mechanism of lipid peroxidation
in hepatocyte cultures but suggest that as a pathologic event lipid peroxidation is not expressed in terms of viability during
the first 24 h of hepatocyte culture. 相似文献
2.
Various tests of function have been suggested for assessing hepatocytes recovered from cryopreservation. In this study we have investigated hepatocyte attachment during tissue culture and cellular density in order to assess function and compared them with two classical dye exposure tests. The ability of hepatocytes to exclude trypan blue dye (TB) and metabolize fluorescein diacetate (FDA) was demonstrated. In populations of freshly prepared hepatocytes 88.07% were able to exclude TB and 87.31% were able to metabolize FDA. However in populations of hepatocytes recovered after cryopreservation using 1.5 M dimethyl sulfoxide as cryoprotectant only 33.44% were able to exclude TB and 31.59% able to metabolize FDA. Both of these tests gave the same estimate of functional ability. Density gradient centrifugation of hepatocytes on Percoll 400 (Pharmacia, Uppsala, Sweden) separated two populations of hepatocytes; one (density ca.1.07 g/ml Percoll) in which most of the cells were able to exclude TB and the second (density ca. 1.02 g/ml Percoll) in which they were stained blue. The dense population was highly enriched in dye-excluding hepatocytes: freshly prepared hepatocytes, 92.4%, and cryopreserved hepatocytes, 88.66%. When samples of these cells (2 x 10(6) dye-excluding cells per dish) were tested for their ability to attach to tissue culture dishes only 17.28% of the cryopreserved hepatocytes were able to attach compared to 55.28% of the freshly prepared cells. We conclude that cryopreservation of hepatocytes produces a population of cells which are not metabolically identical to a population of freshly prepared hepatocytes even though they appear to have the same buoyant density and dye-excluding capabilities.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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HAU3是寄主范围很广的放线菌噬菌体。Southern杂交实验表明,HAU3可以整合到吸水链霉菌应城变种10-22和变铅青链霉菌66的突变体ZX1的染色体中,形成溶原,其溶原菌自发释放HAU3,不受热激和紫外线照射的诱导。通过比较HAU3衍生噬粒pIJ8300的DNA酶切片段在加热前、后电泳带谱的区别,将HAU3的cos位点在pIJ8300的图谱上得到了定位。还利用Southern杂交的方法定位了HAU3与宿主形成溶原时附着位点(attP),并利用脉冲电泳技术定位了在变铅青链霉菌ZX7和吸水链霉菌应城变种10-22中形成溶原的附着位点(attB)。这些信息均有利于以HAU3为基础的载体的发展和优化。 相似文献
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mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species 总被引:4,自引:0,他引:4
Reconstructions of the human-African great ape phylogeny by using
mitochondrial DNA (mtDNA) have been subject to considerable debate. One
confounding factor may be the lack of data on intraspecific variation. To
test this hypothesis, we examined the effect of intraspecific mtDNA
diversity on the phylogenetic reconstruction of another Plio- Pleistocene
radiation of higher primates, the fascicularis group of macaque (Macaca)
monkey species. Fifteen endonucleases were used to identify 10 haplotypes
of 40-47 restriction sites in M. mulatta, which were compared with similar
data for the other members of this species group. Interpopulational,
intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of
divergence time and branching order incorporating this variation were
substantially different from those based on single representatives of each
species. We conclude that intraspecific mtDNA diversity is substantial in
at least some primate species. Consequently, without prior information on
the extent of genetic diversity within a particular species, intraspecific
variation must be assessed and accounted for when reconstructing primate
phylogenies. Further, we question the reliability of hominoid mtDNA
phylogenies, based as they are on one or a few representatives of each
species, in an already depauperate superfamily of primates.
相似文献
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The molecular mechanisms leading to asexuality remain little understood despite their substantial bearing on why sexual reproduction is dominant in nature. Here, we examine the role of hybridization in the origin and spread of obligate asexuality in Daphnia pulex, arguably the best‐documented case of contagious asexuality. Obligately parthenogenetic (OP) clones of D. pulex have traditionally been separated into ‘hybrid’ (Ldh SF) and ‘nonhybrid’ (Ldh SS) forms because the lactase dehydrogenase (Ldh) locus distinguishes the cyclically parthenogenetic (CP) lake dwelling Daphnia pulicaria (Ldh FF) from its ephemeral pond dwelling sister species D. pulex (Ldh SS). The results of our population genetic analyses based on microsatellite loci suggest that both Ldh SS and SF OP individuals can originate from the crossing of CP female F1 (D. pulex × D. pulicaria) and backcross with males from OP lineages carrying genes that suppress meiosis specifically in female offspring. In previous studies, a suite of diagnostic markers was found to be associated with OP in Ldh SS D. pulex lineages. Our association mapping supports a similar genetic mechanism for the spread of obligate parthenogenesis in Ldh SF OP individuals. Interestingly, our study shows that CP D. pulicaria carry many of the diagnostic microsatellite alleles associated with obligate parthenogenesis. We argue that the assemblage of mutations that suppress meiosis and underlie obligate parthenogenesis in D. pulex originated due to a unique historical hybridization and introgression event between D. pulex and D. pulicaria. 相似文献
9.
E. W. Evans N. R. Carlile M. B. Innes N. Pitigala 《Journal of Applied Entomology》2013,137(5):383-391
Variation in weather among years may affect biological control of insect pests by influencing how well matched in phenology specialist parasitoids are with their pest hosts. A 10‐year study in western North America (Utah) revealed greater change with warm versus cool springs in the life cycle timing of the cereal leaf beetle (CLB), Oulema melanopus (L.), than of its principal enemy, the parasitoid wasp Tetrastichus julis (Walker). The beetle laid eggs, and larval populations developed in crop fields earlier on a calendar‐day basis, but nonetheless after more degree‐days had accumulated, in warmer than in cooler springs. The phenology of parasitism by wasps, in contrast, varied little among springs in relation to accumulated degree‐days. Consequently, in warmer springs, larval phenology of the CLB was delayed relative to adult parasitoid activity, and parasitism was reduced. Presently, a significant degree of biological control of the CLB results from parasitism by T. julis. By promoting phenological mismatch between host and parasitoid, however, a warming climate could weaken this biological control of the insect pest. 相似文献
10.