栽培黄瓜与野黄瓜正反杂交的几种同工酶分析

运用天冬氨酸转氨酶(AAT)、苹果酸脱氢酶(MDH)以及酯酶(EST)3种同工酶对栽培黄瓜"长春密刺"Cucumis sativus cv. Changchunmici (2n=14)与野黄瓜C. hystrix (2n=24)的正反交种间杂种F1 (正交: 野黄瓜×栽培黄瓜"长春密刺", 反交: 栽培黄瓜"长春密刺"×野黄瓜)及其双亲进行鉴定和比较研究。结果表明: 正反交种间杂种F1主要表现为双亲酶带的互补, 同时还形成4个杂合带(Aat-1-94、Aat-2-104、Mdh-3-102和Est-5-102)。上述3种酶均能准确地鉴定种间杂种的真实性。研究还发现正反交杂种F1的AAT和MDH的酶谱分别在酶带数目和强弱上表现出一定的差异, 进一步证实了野黄瓜与栽培黄瓜杂交存在正反交差异。     

Production of n + 1 plants and tetrasomics by means of anther culture of trisomic plants in rice (Oryza sativa L.)

Summary Eleven primary trisomics of rice, variety Nipponbare, were subjected to anther culture. The 12th trisomic did not produce normal anthers. A total of 3,734 plants were obtained, which were examined morphologically at the seedling stage in the greenhouse. A number of plants appeared in the progenies of ten trisomics which had unique morphological features. The frequency of these variant types differed among different progenies. Cytological observations revealed that 43 variant plants in the progenies of nine trisomics had 13 chromosomes (n + 1), and 56 were tetrasomics (2n = 26). The tetrasomic plants in the progeny of a trisomic were morphologically identical. Similarly, n + 1 plants in the progeny of a trisomic were also identical. Plants with 23, 25, 36, 39, and 73 chromosomes were also obtained. Results show that valuable aneuploids such as n + 1 and 2n + 2 can be obtained in the anther-culture-derived progenies of trisomics.     

Production and characterization of antibodies against C-terminal peptide of protein F1: A novel phosphorylation at serine 209 of the peptide by protein kinase C

Protein F1 (GAP-43, B-50, neuromodulin, P-57), a neural tissue-specific phosphoprotein enriched in the growth cones of elongating neurites, is suggested to be involved in synaptic plasticity, neuronal development, and neurotransmitter release. In this study, a 21 amino acid polypeptide (AKPKES^* ARQDEGKEDPEADQE) that corresponds to the C-terminus sequence of protein F1 (from position 204–224) was synthesized and used to produce anti-protein F1 antibodies. Immunoblot analysis has demonstrated that the prepared antibodies recognized intact protein F1. Protein F1 and the synthesized F1 peptide were phosphorylated in vitro by PKC. Furthermore, phosphorylated protein F1 was immunoprecipitated by anti-F1 peptide antibodies demonstrating that these antibodies recognized both native, non-phosphorylated and phosphorylated protein. The anti-protein F1 antibodies also stained the plasma membranes of cell bodies and neurities of mouse neuronal cultures obtained from 14-day old spinal embryonic tissue. By contrast, no glial cells were stained. These data suggest that serine 209 at the C-terminus of protein F1 may be a substrate for PKC phosphorylation in vivo. In addition, antibodies raised against F1 peptide revealed protein F1 immunoreactivity that outlined all neurites of cultured mouse spinal neurons.Abbreviations used IgG immunoglobulin G - KLH keyhole limpet haemocyanin - OAG L--1-oleoyl-2-acetoyl-sn-3-glycerol - PAGE polyacrylamide gel electrophoresis - PBS phosphate-buffered saline - PKC protein kinase C - SDS sodium dodecyl sulfate - TFA trifluoroacetic acid     

A quantitative study of spermatogonial multiplication and stem cell renewal in the C3H/101 F1 hybrid mouse

In whole mounts of seminiferous tubules of C3H/101 F₁ hybrid mice, spermatogonia were counted in various stages of the epithelial cycle. Furthermore, the total number of Sertoli cells per testis was estimated using the disector method. Subsequently, estimates were made of the total numbers of the different spermatogonial cell populations per testis.

The results of the cell counts indicate that the undifferentiated spermatogonia are actively proliferating from stage XI until stage IV. Three divisions of the undifferentiated spermatogonia are needed to obtain the number of A₁ plus undifferentiated spermatogonia produced each epithelial cycle. Around stage VIII almost two-thirds of the A_pr and all of the A_al spermatogonia differentiate into A₁ spermatogonia. It was estimated that there are 2.5 × 10⁶ differentiating spermatogonia and 3.3 × 10⁵ undifferentiated spermatogonia per testis. There are about 35,000 stem cells per testis, constituting about 0.03% of all germ cells in the testis. It is concluded that the undifferentiated spermatogonia, including the stem cells, actively proliferate during about 50% of the epithelial cycle.     

Genetic structure of a hybrid zone between two violets,Viola rossii Hemsl. and V. bissetii Maxim.: dominance of F1 individuals in a narrow contact range

The genetic composition of a hybrid zone can provide insight into the evolution of diversification in plants. We carried out morphological and amplified fragment length polymorphism analyses to investigate the genetic composition of a hybrid zone between two violets, Viola bissetii Hemsl. and Viola rossii Maxim. Our aim was to clarify the formation and maintenance of hybrids between these Viola species. We found that most hybrid individuals (V. bissetii × V. rossii) were of the F₁ generation, with a few of the F₂ generation. We found no backcrosses. The scarcity of post‐F₁ hybrids indicates that a species barrier is established between the parental species. The F₁‐dominated hybrid zone occupied only a narrow, intermediate ecotone between the parental habitats, suggesting that selection by environmental factors against hybrids may help to maintain the current conditions in this hybrid zone.     

A hybrid zone dominated by fertile F1s of two alpine shrub species, Phyllodoce caerulea and Phyllodoce aleutica, along a snowmelt gradient

In alpine ecosystems, the steep environmental gradients produced by the difference in snowmelt timing create a dynamic selective regime for alpine plants. As these gradients directly alter flowering phenology, they can affect pollen-mediated gene flow among populations of single and related species. In northern Japan, we found a hybrid zone dominated by fertile F(1)s of two alpine shrub species, Phyllodoce caerulea and P. aleutica, along a snowmelt gradient. Seed germination confirmed the fertility of F(1) hybrid, making the rarity and absence of backcross and F(2) plants puzzling. The long-term clonal perpetuation of F(1) hybrids (at least a few thousand years ago) contributes the maintenance of this unique hybrid zone. The distribution patterns of chloroplast DNA haplotypes suggest that F(1) formation might be caused by directional pollen flow between parental species along the snowmelt gradient. Based on these results, we discuss the ecological and evolutionary significance of this unique hybrid zone.     

Correlation between the high expression of C/EBPbeta protein in F442A cells and their relative resistance to antiadipogenic action of TCDD in comparison to 3T3-L1 cells

We compared the ability of two clonally derived murine preadipocyte cell lines, 3T3-L1(L1) and 3T3-F442A (F442A), to differentiate after treatment by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and found that the former cell line was clearly suppressed by TCDD but the latter was not. It was initially postulated that the easiest way to explain the lack of response to TCDD in F442A cells could be an alteration in aryl hydrocarbon receptor (AhR) functionality. This hypothesis was tested first, but no differences were found in the levels or functions of AhR. To find an alternate explanation for such a differential effect of TCDD, we tested the action of several diagnostic agents on the process of adipocyte differentiation of these two cells. No differences were found between these two lines of cells in the susceptibility to the antiadipogenic action of 12-0-tetradecanoylphorbol-13-acetate (TPA), or to TNFalpha, indicating that the basic biochemical components engaged in the antiadipogenic actions of these agents in these two cell lines are similar. In contrast, F442A cells were found to be more resistant to the antiadipogenic action of EGF or TGFbeta than L1 cells which were tested side by side. Based on the knowledge that TNFalpha preferentially affects C/EBPalpha and that TGFbeta specifically controls C/EBPbeta and delta in their antiadipogenic action, we hypothesized that the major cause for the differential response of these two similar cell lines could be the insensitivity of C/EBPbeta and/or delta of F442A cells to the action of TCDD. We could obtain supporting data for this hypothesis, showing that in F442A cells, the level of C/EBPbeta is already high even before the addition of adipocyte differentiation factors and that TCDD did not cause any significant changes in the titer of C/EBPbeta.     

Identification of cis-regulatory elements from the C. elegans Hox gene lin-39 required for embryonic expression and for regulation by the transcription factors LIN-1, LIN-31 and LIN-39

Expression of the Caenorhabditis elegans Hox gene lin-39 begins in the embryo and continues in multiple larval cells, including the P cell lineages that generate ventral cord neurons (VCNs) and vulval precursor cells (VPCs). lin-39 is regulated by several factors and by Wnt and Ras signaling pathways; however, no cis-acting sites mediating lin-39 regulation have been identified. Here, we describe three elements controlling lin-39 expression: a 338-bp upstream fragment that directs embryonic expression in P5-P8 and their descendants in the larva, a 247-bp intronic region sufficient for VCN expression, and a 1.3-kb upstream cis-regulatory module that drives expression in the VPC P6.p in a Ras-dependent manner. Three trans-acting factors regulate expression via the 1.3-kb element. A single binding site for the ETS factor LIN-1 mediates repression in VPCs other than P6.p; however, loss of LIN-1 decreases expression in P6.p. Therefore, LIN-1 acts both negatively and positively on lin-39 in different VPCs. The Forkhead domain protein LIN-31 also acts positively on lin-39 in P6.p via this module. Finally, LIN-39 itself binds to this element, suggesting that LIN-39 autoregulates its expression in P6.p. Therefore, we have begun to unravel the cis-acting sites regulating lin-39 Hox gene expression and have shown that lin-39 is a direct target of the Ras pathway acting via LIN-1 and LIN-31.