RFLP mapping of QTLs for yield and related characters in rice (Oryza sativa L.)

Quantitative triat loci (QTLs) for yield and related traits in rice were mapped based on RFLP maps from two indica/indica F₂ populations, Tesanai 2/CB and Waiyin 2/CB. In Tesanai 2/CB, 14 intervals carrying QTLs for eight traits were detected, including 3 for grain weight per plant (GWT), 2 for number of panicles per plant (NP), 2 for number of grains per panicle (NG), 1 for total number of spikelets per panicle (TNS), 1 for spikelet fertility (SF), 3 for 1000-grain weight (TGWT), 1 for spikelet density (SD), and 1 for number of first branches per main panicle. The 3 QTLs for GWT were located on chromosomes 1, 2, and 4, with 1 in each chromosome. The additive effect of the single locus ranged from 2.0 g to 9.1 g. A major gene (np4) for NP was detected on chromosome 4 within the interval of RG143–RG214, about 4cM for RG143, and this locus explained 26.1% of the observed phenotypic variance for NP. The paternal allele of this locus was responsible for reduced panicles per plant (3 panicles per plant). In another population, Waiyin 2/CB, 12 intervals containing QTLs for six of the above-mentioned traits were detected, including 3 for GWT, 2 for each of NP, TNS, TGWT and SD, 1 for SF. Three QTLs for GWT were located on chromosome 1, 4, and 5, respectively. The additive effect of the single locus for GWT ranged from 6.7 g to 8.8 g, while the dominance effect was 1.7–11.5 g. QTL mapping in two populations with a common male parent is compared and discussed.     

部分酶解酵母高效电击转化研究

以酵母质粒YCp50为外源DNA,电击转化部分酶解酵母宿主菌AB1380,转化效率稳定在10~6转化子/μg质粒DNA左右,比不酶解酵母或酵母原生质球作受体的电击转化效率高一个数量级以上,也比PEG介导的酵母原生质球转化高3～5倍,而且适合于大片段DNA如水稻YAC分子的转化。达最佳转化时的有关技术参数为:新接菌种通气培养至细胞密度1×10~8～1.5×10~8个/ml;转化时细胞密度控制在1×10~9～1.5×10~9个/ml;每毫升酶解缓冲液加15u溶菌酶(lyticase),30℃下处理酵母5min进行部分酶解;电击时,电场设置在6.25kV/cm、电容25μF,电击后直接铺板。     

Generation and ex vivo expansion of HTLV-1 specific CD8+ cytotoxic T-lymphocytes for adoptive immunotherapy

CD8(+) cytotoxic T-lymphocytes (CTLs) have been proven, in multiple animal models, to be the most powerful antiviral and antitumor components of the immune system. We have developed a protocol to activate and expand tumor and virus peptide-specific CD8(+) T-lymphocytes from the peripheral blood of healthy, human trophic leukemia virus-1 (HTLV-1) seronegative human leucocyte antigen (HLA)-A*0201 individuals. A combination of density-based separation and culture conditions was employed to isolate dendritic cells (DCs), which are the most potent antigen-presenting cells (APCs), and T-lymphocytes. The DCs were pulsed with HLA-A*0201 binding peptides and cultured with autologous T-lymphocytes to generate peptide-specific CTLs. The CTLs were generated against a nine-amino-acid peptide from the Tax protein of HTLV-1. The CTLs were expanded according to a restimulation schedule employing peptide-pulsed autologous monocytes and low-dose interleukin-2 (IL-2) to numbers in excess of 100 x 10(6) cells following 5 weeks of culture. Expanded cells contained primarily CD3(+) T-cells, of which CD8(+) T-lymphocytes constituted greater than two-thirds of the cell population. Obtained CTLs exhibited potent antigen-specific lysis of peptide-pulsed target cells in a dose-dependent fashion in in vitro (51)Cr release cytotoxicity assay. This antigen-specific killing was shown to be HLA class I restricted and mediated by CD8(+) T-lymphocytes. Since the T-lymphocytes were obtained from HTLV-1 seronegative donors, the generation of peptide-specific CTLs represents reliable and reproducible elicitation of a primary immune response in vitro against naive antigens and subsequent expansion of generated CTLs for adoptive immunotherapy. (c) 1996 John Wiley & Sons, Inc.     

Predictive models for phosphorus retention in wetlands

The potential of wetlands to efficiently remove (i.e., act as a nutrient sink) or to transform nutrients like phosphorus under high nutrient loading has resulted in their consideration as a cost-effective means of treating wastewater on the landscape. Few predictive models exist which can accurately assess P retention capacity. An analysis of the north American data base (NADB) allowed us to develop a mass loading model that can be used to predict P storage and effluent concentrations from wetlands. Phosphorus storage in wetlands is proportional to P loadings but the output total phosphorus (TP) concentrations increase exponentially after a P loading threshold is reached. The threshold P assimilative capacity based on the NADB and a test site in the Everglades is approximately 1 g m^–2 yr^–1. We hypothesize that once loadings exceed 1 g m^–2 yr^–1 and short-term mechanisms are saturated, that the mechanisms controlling the uptake and storage of P in wetlands are exceeded and effluent concentrations of TP rise exponentially. We propose a One Gram Rule for freshwater wetlands and contend that this loading is near the assimilative capacity of wetlands. Our analysis further suggests that P loadings must be reduced to 1 g m^–2 yr^–1 or lower within the wetland if maintaining long-term low P output concentrations from the wetlands is the central goal. A carbon based phosphorus retention model developed for peatlands and tested in the Everglades of Florida provided further evidence of the proposed One Gram Rule for wetlands. This model is based on data from the Everglades areas impacted by agricultural runoff during the past 30 years. Preliminary estimates indicate that these wetlands store P primarily as humic organic-P, insoluble P, and Ca bound P at 0.44 g m^–2 yr^–1 on average. Areas loaded with 4.0 g m^–2 yr^–1 (at water concentrations>150 g·L^–1 TP) stored 0.8 to 0.6 g m^–2 yr^–1 P, areas loaded with 3.3 g m^–2 yr^–1 P retained 0.6 to 0.4 g m^–2 yr^–1 P, and areas receiving 0.6 g m^–2 yr^–1 P retained 0.3 to 0.2 g m^–2 yr^–1. The TP water concentrations in the wetland did not drop below 50 g·L^–1 until loadings were below 1 g m² yr^–1 P.     

编码人疱疹病毒－6型核糖核苷酸还原酶和P41蛋白基因的克隆和序列测定

本文报道人疱疹病豢－６型（ＨＨＶ－６）ｐＳＴＹ２８ＤＮＡ片段的序列测定。应用分子克隆、缺损突变体（Ｄｃｌｅｔｉｏｎｍｕｔａｎｔ）制备和序列测定等技术,完成了３．９ｋｂＨＨＶ－６ｐＳＴＹ２８ＤＮＡ片段的全序列测定。经ＤＮＡＳＩＳ核酸蛋白软件分析,该片段含有两个开读框架（ＯＲＦ）核糖核苷酸还原酶（ＲＩＲ）ＯＲＦ有２４１４个核苷酸,可编码８０５个氨基酸;Ｐ４１蛋白由１１００个核苷酸组成。与其他疱疹病毒作氨基酸同源性比较,ＨＨＶ－６ＲｉＲ与人巨细胞病毒（ＨＣＭＶ）有高度同源性,最适记分（Ｏｐｔｉｍｉｚｅｄｓｃｏｒｅ）达４５９。实验结果支持Ｅｓｆｔａｔｈｉｏｕ提出的论点,ＨＨＶ－６属于β－疱疹病毒。     

Studies on homoveratric acid transformation by the ligninolytic fungus Pleurotus eryngii

Homoveratric acid (HVA) degradation was observed in cultures of Pleurotus eryngii lacking lignin peroxidase (LiP) activity. Extracellular enzymes seemed responsible for this transformation, and the lack of activity after ultrafiltration of the culture liquid suggests that the presence of some low-molecular-size compounds is required. This hypothesis is supported by rapid HVA transformation after addition of the synthetic laccase substrate 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) to the ultrafiltered liquid. HVA transformation by the extracellular enzymes from P. eryngii takes place via C-C breakdown and formation of veratryl alcohol, which is further transformed into veratraldehyde. The same major compounds were found during HVA transformation by LiP from Phanerochaete chrysosporium, but this reaction was not stimulated by ABTS. Although the involvement of other enzymes cannot be ruled out, purified laccase from Pleurotus eryngii caused the same HVA transformation pattern in presence of ABTS. Moreover, veratryl alcohol oxidation by P. eryngii laccase was demonstrated in the presence of ABTS. These results suggest that enzymatic systems lacking LiP could be responsible for natural degradation of lignin.     

Pollen-ovule ratio,pollen size,and breeding system in Astragalus (Fabaceae) subgenus Epiglottis: a pollen and seed allocation approach

The correlation between pollen/ovule (P/O) ratio and breeding system has generally been accounted for either on the basis that P/O reflects pollination efficiency, or in terms of the sex allocation theory. The following were assessed for taxa belonging to genus Astragalus subgenus Epiglottis: 1) Degree of correlation between P/O and the breeding system, measured by means of autofertility; 2) The absence or existence of correlation between P/O and pollen grain size; and 3) The ability of various theories to account for the results obtained. Results showed a minimal correlation between P/O and autofertility, and between P/O and pollen grain size in the taxa studied. Analysis of these results in terms of the sex allocation theory enabled this correlation to be explained as a function of the variation existing between taxa with respect to the resources invested in each pollen grain and in each ovule. The predictive capacity of this theory, which has moreover proven valuable in explaining the structural peculiarities of the androecium in these taxa, was also highlighted. The type of self-pollination applicable was also discussed, as was the phenotypic model of selection of self-fertilization considered most plausible for these taxa.     

Purification and characterization of two phosphoglucomutases from Lactococcus lactis subsp. lactis and their regulation in maltose- and glucose-utilizing cells.

Two distinct forms of phosphoglucomutase were found in Lactococcus lactis subsp. lactis, strains 19435 and 65.1, growing on maltose: beta-phosphoglucomutase (beta-PGM), which catalyzes the reversible conversion of beta-glucose 1-phosphate to glucose 6-phosphate in the maltose catabolism, and alpha-phosphoglucomutase (alpha-PGM). beta-PGM was purified to more than 90% homogeneity in crude cell extract from maltose-grown lactococci, and polyclonal antisera to the enzyme were prepared. The molecular mass of beta-PGM was estimated by gel filtration to be 28 kDa; its isoelectric point was 4.8. The corresponding values for alpha-PGM were 65 kDa and 4.4, respectively. The expression of both PGM enzymes was investigated under different growth conditions. The specific activity and amount of beta-PGM per milliliter of cell extract increased with time in lactococci grown on maltose, but the enzyme was absent in lactococci grown on glucose, indicating enzyme synthesis to be induced by maltose in the growth medium. When glucose was added to maltose-grown lactococci, both the specific activity and amount of beta-PGM per milliliter of cell extract decreased rapidly. This suggests that synthesis of beta-PGM is repressed by glucose in the medium. Although the specific activity of alpha-PGM did not change during growth on maltose or glucose, lactococcal strain 19435 showed a much higher specific activity of both alpha- and beta-PGM than strain 65.1 when grown on maltose.     

Comparison of superovulatory response of mature outbred mice treated with FSH or PMSG and developmental potential of embryos produced

A superovulatory treatment for mice based on FSH administration was compared with a standard one based on PMSG. Our aim was to determine if a mean number of embryos recovered per donor could be increased and if in vitro or in vivo viability was affected by the hormonal treatment used. Thus, female Swiss mice were subjected to 2 superovulatory treatments, and the 1-cell and 2-cell stage embryos were cultured in 2 different media to the blastocyst stage or were transferred to pseudopregnant recipients. The data show that despite a lower mating percentage (52% with FSH vs 66% with PMSG), the FSH-treated mice provided twice the number of total embryos (53.4 vs 24.5) with a similar percentage of morphologically normal embryos (74% for FSH vs 69% for PMSG). We also found that in vitro culture results can be influenced by the source of gonadotropins depending on the culture medium used. A culture medium such as CZB which prevents the 2-cell block, provided the same developmental rates regardless of hormonal treatment used. However, with M-16 medium, which does not prevent this blockage, only 39% of the 2-cell FSH-derived embryos and 49% of the PMSG-derived 2-cell embryos developed into blastocysts (P<0.05). FSH-derived embryos resulted in a higher percentage of pregnant recipients (73 vs 56%) than PMSG-derived embryos, but the number of alive fetuses and the number of implantations per pregnant recipient was affected only by the kind of culture system used before transfer. The results show that FSH can provide very good superovulatory response in mice, thus reducing the number of donors needed for a given experiment and providing embryos of at least the same quality as those derived from the standard PMSG treatment.