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91.
92.
对我国首座核电站配套工程的抽水蓄能电站水库蓄水初期的浮游生物进行了调查。蓄水水库由上下两水库组成。两水库的浮游生物种类组成显著不同。上水库浮游植物共记录到30种(属),浮游动物12种(属);下水库浮游植物19种(属);浮游动物25种(属)。上下两水库浮游生物数量均较贫乏,表明浮游生物群落尚处于初期发育阶段,但在局部浅水处已出现小规模的蓝藻水花,认为是水库蓄水初期必然的结果 相似文献
93.
Mixed-phase plants of Griffithsia japonica Okamura spontaneously occurred in a laboratory culture. Four female plants produced tetrasporangia and spermatangia in addition to their normal female reproductive structures (bisexual/mixed-phase plants), and four male plants produced tetrasporangia as well as spermatangia (male/mixed-phase plants). To determine the nuclear ploidy level of these mixed-phase plants, relative nuclear sizes of male, female, tetrasporangial, and mixed-phase plants were measured using a microscopic image analysis system. Haploid gametophytes could be distinguished from diploid tetrasporophytes by relative nuclear sizes, with the later having nuclei twice the size of the former. Relative nuclear sizes of the mixed-phase plants were similar to those of the haploid plants. Thus, the mixed-phase plants were determined to be haploid. Haploid mixed-phase plants of G. japonica have a potential to produce male, female and tetrasporangial reproductive structures. Sex determination models are discussed to explain "haploid" mixed-phase phenomena in red algae . 相似文献
94.
Cucumber (Cucumis sativus L.) seedlings were grafted onto cucumber-(CG) or figleaf gourd- (FG, Cucurbita ficifolia Bouché)seedlings in order to determine the effect of solution temperature(12, 22, and 32°C) on the mineral composition of xylem sapand the plasma membrane K+-Mg++-ATPase activities of the roots.Low solution temperature (12°C) lowered the concentrationof NO3 and H2PO4 in xylem sap of CG plants butnot of FG plants. Concentrations of K+, Ca++ and Mg++ in xylemsap were less affected than anions by solution temperature.The plasma membrane of FG plants grown in 12°C solutiontemperature showed the highest K+- Mg++-ATPase activity at allATP concentrations up to 3 mM and at low reaction temperatureup to 12°C, indicating resistance of figleaf gourd to lowroot temperature. (Received December 27, 1994; Accepted March 10, 1995) 相似文献
95.
96.
Hyung-Joo Jin Jeong–Ha Kim Chul Hyun Sohn R.E. DeWreede Tae–Joo Choi G.H.N. Towers J.B. Hudson Yong–Ki Hong 《Journal of applied phycology》1997,9(4):383-388
Fifty-nine species of marine macrophytes from the coasts of British Columbia, Canada and Korea have been screened for the
presence of PCR inhibitors, namely inhibitors of Taq DNA polymerase. Eleven of the species displayed some inhibitor activity.
At the concentration of 5 μg of methanol extract in 25μL reaction mixture of PCR containing 1.5 unit of Taq DNA polymerase,
one (Ulva sp.) of 8 Chlorophyta, eight (Colpomenia bullosa, Ecklonia cava, Endarachne binghamiae, Fucus distichus, Hizikia
fusiformis, Sargassum confusum, Sargassum sagamianum, and Sargassum thunbergii) of 28 Phaeophyta, and one (Symphyocladia latiuscula)
of 34 Rhodophyta showed inhibition in PCR amplification. In the case of the water extract, two (Cladophora columbiana, Ulva
sp.) Chlorophyta, seven (Endarachne binghamiae, Fucus distichus, Hizikia fusiformis, Sargassum confusum, Sargassum sagamianum,
Sargassum horneri, Scytosiphon dotyi) Phaeophyta, no Rhodophyta and one (Phyllospadix scouleri) seagrass showed inhibition
in PCR amplification. the methanol fraction of Sargassum confusum and the water fraction of Fucus gardneri (mid–intertidal)
have been found to inhibit PCR at level as low as 0.5 μg in 25μL of PCR reaction mixture.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
97.
To understand the role of chromatin structure in the expression of the mouse protamine 1, protamine 2, and transition protein
2 genes during spermatogenesis, we have examined the genomic organization of this cluster of ``haploid-specific' genes. As
seen in the human genome, protamine 2, transition protein 2, and approximately 2.8 kb of a CpG island, hereafter called CpG
island-dTP2, were clustered in a small region. Methylation analyses of this region have demonstrated that i) unlike most other
tissue-specific genes, the protamine 1, protamine 2, and transition protein 2 genes were located in a large methylated domain
in round spermatids, the cell type where they are transcribed, ii) the protamine 1 gene was only partially methylated in somatic
cells and in testes from 7-day-old mice, and iii) the approximately 2 kb upstream and downstream of the CpG island-dTP2 were
only partially methylated in somatic tissues. DNase I analysis revealed the presence of at least five strong DNase I hypersensitive
sites over the CpG island-dTP2 in somatic tissues, but not in germ cells, and sequence analysis indicated that the CpG island-dTP2
is homologous to a CpG island located approximately 10.6 kb downstream of the human transition protein 2 gene. Although the
nature of a CpG island-dTP2 and the function of a CpG island-dTP2-containing somatic tissue-specific DNase I hypersensitive
sites in close proximity to the germ cell-specific gene cluster are unclear, the ``open' chromatin structure of the CpG island-dTP2
may be responsible for the partial methylation pattern of the flanking sequences including the transition protein 2 gene in
somatic tissues.
Received: 6 September 1996 / Accepted: 14 January 1997 相似文献
98.
T. N. Ferraro G. T. Golden G. G. Smith N. J. Schork P. St. Jean C. Ballas H. Choi W. H. Berrettini 《Mammalian genome》1997,8(3):200-208
Mature DBA/2J (D2) mice are very sensitive to seizures induced by various chemical and physical stimuli, whereas C57BL/6J
(B6) mice are relatively seizure resistant. We have conducted a genome-wide search for quantitative trait loci (QTLs) influencing
the differential sensitivity of these strains to kainic acid (KA)-induced seizures by studying an F2 intercross population. Parental, F1, and F2 mice (8–10 weeks of age) were injected subcutaneously with 25 mg/kg of KA and observed for 3 h. Latencies to focal and generalized
seizures and status epilepticus were recorded and used to calculate an overall seizure score. Results of seizure testing indicated
that the difference in susceptibility to KA-induced seizures between D2 and B6 mice is a polygenic phenomenon with at least
65% of the variance due to genetic factors. First-pass genome screening (10-cM marker intervals) in F2 progeny (n = 257) documented a QTL of moderate effect on Chromosome (Chr) 1 with a peak LOD score of 5.5 (17% of genetic
variance explained) localized between D1Mit30 and D1Mit16. Provisional QTLs of small effect were detected on Chr 11 (D11Mit224–D11Mit14), 15 (D15Mit6–D15Mit46) and 18 (D18Mit9–D18Mit144). Multiple locus models generally confirmed the Mapmaker/QTL results and also provided evidence for another QTL on Chr 4
(D4Mit9). Multilocus analysis of seizure severity suggested that additional loci on Chrs 5 (D5Mit11), 7 (D7Mit66), and 15 (D15Nds2) might also contribute to KA-induced seizure response. Overall, our results document a complex genetic determinism for KA-induced
seizures in these mouse strains with contributions from as many as eight QTLs.
Received: 16 April 1996 / Accepted: 21 October 1996 相似文献
99.
Identification of three genetic loci controlling leaf senescence in Arabidopsis thaliana 总被引:23,自引:3,他引:20
Sung Aeong Oh Joon-Hyun Park Gyu In Lee Kyung Hee Paek Soon Ki Park Hong Gil Nam 《The Plant journal : for cell and molecular biology》1997,12(3):527-535
Four mutants that show the delayed leaf senescence phenotype were isolated from Arabidopsis thaliana . Genetic analyses revealed that they are all monogenic recessive mutations and fall into three complementation groups, identifying three genetic loci controlling leaf senescence in Arabidopsis . Mutations in these loci cause delay in all senescence parameters examined, including chlorophyll content, photochemical efficiency of photosystem II, relative amount of the large subunit of Rubisco, and RNase and peroxidase activity. Delay of the senescence symptoms was observed during both age-dependent in planta senescence and dark-induced artificial senescence in all of the mutant plants. The results indicate that the three genes defined by the mutations are key genetic elements controlling functional leaf senescence and provide decisive genetic evidence that leaf senescence is a genetically programmed phenomenon controlled by several monogenic loci in Arabidopsis . The results further suggest that the three genes function at a common step of age-dependent and dark-induced senescence processes. It is further shown that one of the mutations is allelic to ein2-1 , an ethylene-insensitive mutation, confirming the role of ethylene signal transduction pathway in leaf senescence of Arabidopsis . 相似文献
100.
To study the reliabiliity of formulas for calculating mean skin temperature (T
sk), values were computed by 18 different techniques and were compared with the mean of 10,841 skin temperatures measured by
infrared thermography. One hundred whole-body infrared thermograms were scanned in ten resting males while changing the air
temperature from 40° C to 4° C. Local, regional average and mean skin temperatures were obtained using an image processing
system. The agreement frequency, defined as the percentage of the calculated T
sk values which agreed with the corresponding infrared thermographic T
sk within ±0.2° C, ranged for with the various formulas from 7% to 80%. In many sites, the local skin temperature did not coincide
with the regional average skin temperature. When the local skin temperatures which showed the highest percentage similarity
to the regional average skin temperature within ±0.4° C were applied to the formula, the agreement frequency was markedly
improved for all formulas. However, the agreement frequency was not affected by changing the weighting factors from specific
constants to individually measured values of regional surface area. By applying the physiologically reliable accuracy range
of ±0.2° C in the moderate and ±0.4° C in the cool condition, agreement frequencies of at least 95% were observed in formulas
involving seven or more skin temperature measurement sites, including the hand and foot. We conclude that calculation of a
reliable mean skin temperature must involve more than seven skin temperature measurement sites regardless of ambient temperature.
Optimal sites for skin temperature measurement are proposed for various formulas.
Received: 2 December 1996 / Accepted: 25 June 1997 相似文献