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M. L. Dini J. O'Donnell S. R. Carpenter M. M. Elser J. J. Elser A. M. Bergquist 《Hydrobiologia》1987,150(2):185-191
The timing and magnitude of diel migration in two daphnid assemblages were determined from a series of vertical profiles of daphnid size distribution. Animals were collected concurrently for gut fullness determination. Only large daphnids (> 1.4 mm) migrated, but these animals could account for substantial vertical and diel differences in phosphorus excretion rate. Gut fullness measurements and time courses of diel vertical migration suggested that large Daphnia can cause a net downward flux of phosphorus during summer in thermally stratified lakes. 相似文献
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Processive replication of single-stranded DNA templates by the herpes simplex virus-induced DNA polymerase 总被引:13,自引:0,他引:13
The DNA polymerase encoded by herpes simplex virus 1 consists of a single polypeptide of Mr 136,000 that has both DNA polymerase and 3'----5' exonuclease activities; it lacks a 5'----3' exonuclease. The herpes polymerase is exceptionally slow in extending a synthetic DNA primer annealed to circular single-stranded DNA (turnover number approximately 0.25 nucleotide). Nevertheless, it is highly processive because of its extremely tight binding to a primer terminus (Kd less than 1 nM). The single-stranded DNA-binding protein from Escherichia coli greatly stimulates the rate (turnover number approximately 4.5 nucleotides) by facilitating the efficient binding to and extension of the DNA primers. Synchronous replication by the polymerase of primed single-stranded DNA circles coated with the single-stranded DNA-binding protein proceeds to the last nucleotide of available 5.4-kilobase template without dissociation, despite the 20-30 min required to replicate the circle. Upon completion of synthesis, the polymerase is slow in cycling to other primed single-stranded DNA circles. ATP (or dATP) is not required to initiate or sustain highly processive synthesis. The 3'----5' exonuclease associated with the herpes DNA polymerase binds a 3' terminus tightly (Km less than 50 nM) and is as sensitive as the polymerase activity to inhibition by phosphonoacetic acid (Ki approximately 4 microM), suggesting close communication between the polymerase and exonuclease sites. 相似文献
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A Vellodi J R Hobbs N M O'Donnell B S Coulter K Hugh-Jones 《BMJ (Clinical research ed.)》1987,295(6610):1375-1376
Allogenic bone marrow transplantation was carried out on a 3 year old girl with Niemann-Pick disease type B. Successful engraftment was achieved, and nine months after the procedure there was definite clearing of the sphingomyelin from the liver and pronounced clearing from the bone marrow. Any patient with Niemann-Pick disease type B complicated by early or severe hepatic impairment should be considered for bone marrow transplantation. 相似文献
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I J O'Donnell J K Dineen B M Wagland S Letho T A Dopheide W N Grant C W Ward 《International journal for parasitology》1989,19(7):793-802
The excretory-secretory products of exsheathed third-stage larvae of Trichostrongylus colubriformis conferred some protection to guinea pigs against homologous challenge. A glycoprotein with an apparent molecular mass of approximately 94 kDa was the dominant immunogen in post-exsheathment products. Immunoblots revealed IgG antibodies to this glycoprotein in sera from multiply-infected guinea pigs and some sheep, and in sera of guinea pigs after three truncated infections which had been restricted by anthelmintic treatments to development of the third parasitic stage. IgA antibodies to this protein were also found in intestinal lymph of a naturally infected sheep. Fluorescent antibody studies indicated that this 94 kDa component was associated with cells in the central body cavity of third-stage larvae, but was absent from fourth-stage larvae or adult worms. Fractionation and protection assays in guinea pigs revealed that while the native and aggregated 94 kDa protein conferred some host protection, it was not the only protective component of the excretory-secretory products of exsheathed third-stage larvae of T. colubriformis. 相似文献
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Phylogenetic distribution in the genus Mus of t-complex-specific DNA and protein markers: inferences on the origin of t-haplotypes 总被引:8,自引:0,他引:8
Delarbre C; Kashi Y; Boursot P; Beckmann JS; Kourilsky P; Bonhomme F; Gachelin G 《Molecular biology and evolution》1988,5(2):120-133
We have examined the phylogenetic distribution of two t-specific markers
among representatives of various taxa belonging to the genus Mus. The
centromeric TCP-1a marker (a testicular protein variant specific for all
t-haplotypes so far studied) has also been apparently detected in several
non-t representatives of the Mus IVA, Mus IVB, and probably M. cervicolor
species. By contrast, a t-specific restriction- fragment-length
polymorphism allele (RFLP) of the telomeric alpha- globin pseudogene DNA
marker alpha-psi-4 was found only in animals belonging to the M.
musculus-complex species either bearing genuine t- haplotypes or, like the
M. m. bactrianus specimen studied here, likely to do so. This t-specific
alpha-psi-4 RFLP allele was found to be as divergent from the RFLP alleles
of the latter, non-t, taxonomical groups as it is from Mus 4A, Mus 4B, or
M. spretus ones. These results suggest the presence of t-haplotypes and of
t-specific markers in populations other than those belonging to the M. m.
domesticus and M. m. musculus subspecies, implying a possible origin for
t-haplotypes prior to the radiation of the most recent offshoot of the Mus
genus (i.e., the spretus/domesticus divergence), some 1-3 Myr ago.
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