MORPHOLOGY AND CYTOLOGY OF TILLETIA CARIES AND T. CONTROVERSA IN AXENIC CULTURE

On a wheat-based medium, the pathogenic phase of the common and dwarf bunt fungi grew slowly at 15–18 C and continued to produce massive quantities of teliospores in all subcultures for over 2 years. At warmer temperatures or on a chemically defined medium, the teliosporogenic colonies reverted to haploid mononucleate colonies. The hyphae of the teliosporogenic colonies were stained with a modified Giemsa technique and found to be thick, contorted, highly branched and short celled with usually one or two nuclei per cell. In contrast, the haploid mononucleate hyphae were thinner, straighter, and longer and never contained more than one nucleus per cell. The vegetative hyphae of T. caries and T. controversa were indistinguishable. Teliospores, formed at the terminal end of binucleate hyphae, were initially binucleate but became mononucleate before the mature cell wall formed.     

GENETIC VARIATION IN TRAGOPOGON SPECIES: ADDITIONAL ORIGINS OF THE ALLOTETRAPLOIDS T. MIRUS AND T. MISCELLUS (COMPOSITAE)

Genetic diversity in the introduced diploids Tragopogon dubius, T. porrifolius, and T. pratensis and their neoallotetraploid derivatives T. mirus and T. miscellus was estimated to assess the numbers of recurrent, independent origins of the two tetraploid species in the Palouse region of eastern Washington and adjacent Idaho. These tetraploid species arose in this region, probably within the past 50–60 yr, and provide one of the best models for the study of polyploidy in plants. The parental species of both T. mirus and T. miscellus have been well documented, and each tetraploid species has apparently formed multiple times. However, a recent survey of the distributions of these allotetraploids revealed that both tetraploid species have expanded their ranges considerably during the past 50 yr, and several new populations of each species were discovered. Therefore, to evaluate the possibility that these recently discovered populations are of recent independent origin, a broad analysis of genetic diversity in T. mirus, T. miscellus, and their diploid progenitors was conducted. Analyses of allozymic and DNA restriction site variation in all known populations of T. mirus and T. miscellus in the Palouse and several populations of each parental diploid species revealed several distinct genotypes in each tetraploid species. Four isozymic multilocus genotypes were observed in T. mirus, and seven were detected in T. miscellus. Tragopogon mirus possesses a single chloroplast genome, that of T. porrifolius, and two distinct repeat types of the 18S-26S ribosomal RNA genes. Populations of T. miscellus from Pullman, Washington, have the chloroplast genome of T. dubius; all other populations of T. miscellus have the chloroplast DNA of T. pratensis. All populations of T. miscellus combine the ribosomal RNA repeat types of T. dubius and T. pratensis, as demonstrated previously. When all current and previously published data are considered, both T. mirus and T. miscellus appear to have formed numerous times even within the small geographic confines of the Palouse, with estimates of five to nine and two to 21 independent origins, respectively. Such recurrent polyploidization appears to characterize most polyploid plant species investigated to date (although this number is small) and may contribute to the genetic diversity and ultimate success of polyploid species.     

GENETIC VARIATION IN THE EPIPHYTES TILLANDSIA IONANTHA AND T. RECURVATA (BROMELIACEAE)

The genetic structure of two epiphytic species, Tillandsia ionantha and T. recurvata, was investigated using enzyme electrophoresis. Electrophoretic data suggest that T. ionantha and T. recurvata differ in breeding system, in agreement with predictions based on their strikingly different floral morphologies. Electrophoretic data suggest extremely high levels of inbreeding for T. recurvata, whereas Tillandsia ionantha exhibits characteristics of an outcrossing species. Values of P, H, and mean number of alleles per locus are much higher in T. ionantha than in T. recurvata. The mean value of F_IS for T. ionantha is low (0.056), closely approaching expectations at Hardy-Weinberg equilibrium. In contrast, the mean value of F_IS in T. recurvata (1.000) indicates a complete absence of heterozygotes. The two species also differ in genetic structure. Low F_ST values for T. ionantha indicate little variation in allele frequencies among populations. In contrast, F_ST values are high for T. recurvata, suggesting substantial genetic heterogeneity among populations. In addition, the mean value of I is higher in T. ionantha (0.995) than in T. recurvata (0.931). Population genetic data are in agreement with the suggestion of Benzing (1978), who proposed that extreme epiphytes such as T. recurvata, would be characterized by increased autogamy ensuring high seed set. Due to high chromosome numbers in Bromeliaceae (most taxa have x = 25), the family has been considered polyploid. However, with the exception of an additional isozyme for PGM in T. recurvata, the two species are isozymically diploid.     

八倍体小偃麦与硬粒小麦及其杂种F_1的小孢子发生和花粉发育的细胞学研究

用压片法对八倍体小偃麦与硬粒小麦及其杂种F_1小孢子发生和花粉发育进行了详细的细胞学观察。结果表明,两亲本八倍体小偃麦和硬粒小麦的小孢子发生和花粉发育是基本正常的,二者结实率也基本正常。[八倍体小偃麦×硬粒小麦]F_1小孢子发生过程非常紊乱,花粉母细胞减数分裂中期Ⅰ出现较高频率的单价体和多价体,其相对紊乱系数高达0.67;减数分裂晚后期,每个细胞落后染色体平均3.56条;四分体期,每个四分体微核数平均2.82个。在杂种F_1花粉发育的每个时期都可产生不同频率的败育花粉。在三细胞成熟花粉期,杂种F_1可育花粉百分率为67.36%,基本能够满足传粉受精的需要,但其结实率仅为2.79%,远远低于两亲本结实率。因此杂种F_1花粉的败育不是导致其结实率低的主导因素。     

利用原位杂交技术检测免疫球蛋白重链mRNA在T和B淋巴瘤内的表达

应用原位杂交技术和免疫组织化学法对８例Ｂ淋巴瘤和４例Ｔ淋巴瘤进行了ＩｇＨｍＲＮＡ和ＩｇＭ,κ,λ的检测。结果显示,８例Ｂ淋巴瘤ＩｇＨｍＲＮＡ均为阳性,位于胞核周围,有的ｍＲＮＡ阳性反应成点状位于胞质的一侧。７例胞质中ＩｇＭ,κ或λ为阳性。１例胞质内无ＩｇＭ,κ或λ,但胞核内ＩｇＨｍＲＮＡ阳性反应成点状分布,可能是初级ＲＮＡ转录。在Ｔ淋巴瘤中,只有一例胞核内出现初级ＲＮＡ转录,因为早期Ｔ淋巴瘤,也有Ｄ、Ｊ基因片段的重排     

中国蹄盖蕨属日本蹄盖蕨组植物的分类与分布

本文报道了中国蹄盖蕨属日本蹄盖蕨组植物２系８种,有分种检索表,文献引证和标本引证以及本组植物的分布。     

SARCOPLASMIC RETICULUM AND T TUBULES IN DIFFERENTIATING RAT SKELETAL MUSCLE

An electron microscope study has been made of the distribution of membrane couplings between the sarcoplasmic reticulum (SR) and either the plasmalemma or the T tubules in fetal and neonatal rat intercostal muscle. Within primitive muscle cells at 12 days of gestation, the SR forms both simple and specialized membrane junctions with the plasmalemma; caveolae are very few, and T tubules are not detected. Undifferentiated cells neighbor muscle cells. Occasionally these cells contain subsurface couplings between the endoplasmic reticulum and plasmalemmae. Possible relationships between these couplings and the peripheral couplings of muscle cells are discussed. By 15–18 days of gestation, caveolae and beaded T tubules, comparable to those of cultured muscle, develop; T tubules lie along-side myofibrils and are rarely transverse. SR couples both to T tubules and to plasmalemmae during this period. T tubules with lineal profiles appear after further development and their orientation transverse to A–I junctions becomes increasingly evident. Membrane couplings between SR and T tubules also increase in number, whereas the incidence of peripheral coupling declines rapidly Evidence suggests that peripheral couplings are swept into myotubes as caveolae proliferate and T tubules form. SR thus appears to initially couple with the plasmalemma and then to await T tubular growth. This contrasts with the developmental pattern described in cultured chick muscle in which peripheral couplings are not reported and T tubules with diads and triads occur at very primitive stages of muscle differentiation.     

中间偃麦草与小麦杂种配子形成途径的细胞学研究

以中间偃麦草与小麦烟农在１５的发杂种子Ｆ１及其５个自交和回交世代（Ｆ２,Ｆ３,ＢＣ１,ＢＣ２,ＢＣ３）为材料,对杂种Ｆ１配子形成途径的细胞学特点进行了研究。结果表明,杂种Ｆ１减数第一分裂基本正常,在减数第二分裂观察到由于当染色体不对称分离产生的无染色质和仅带有微核的子细胞,小孢子染色体数目为２４～３５条,根据ＢＣ１推算的Ｆ１产生的雌配子染色体数目为２０～３５条,Ｆ２根尖细胞和花粉母细胞内染色体数目     

EXPERIMENTAL STUDIES OF PLEIOTROPY AND EPISTASIS IN ESCHERICHIA COLI. I. VARIATION IN COMPETITIVE FITNESS AMONG MUTANTS RESISTANT TO VIRUS T4

Mutants selected for novel phenotypes frequently exhibit maladaptive pleiotropic effects. One may reasonably ask whether these effects are properties of the novel phenotypes per se, or whether these effects depend upon the particular genotypes conferring the novel phenotypes. To address this issue, I examined an array of independent mutants, derived from Escherichia coli B, that were all completely resistant to the virus T4. Each resistant mutant had maladaptive pleiotropic effects, but there was highly significant variation in competitive fitness among mutants. The degree of reduction in competitive fitness was strongly associated with cross-resistance to virus T7 and with the inferred position of the mutated gene in a complex metabolic pathway. This variation in competitive fitness permits refinement of the resistant phenotype by selection among resistant genotypes. This mechanism complements refinement of the resistant phenotype by selection for epistatic modifiers of maladaptive pleiotropic effects.     

木霉菌株T6木聚糖酶固态发酵条件和酶学性质研究

研究了碳源和氮源、起始pH、接种量及温度等条件对一野生型木霉Trichoderma sp.T6菌株固态发酵产木聚糖酶的影响。在28℃培养4d后,酶活力可达1918IU/g干培养物。酶的最适反应温度为50℃,最适反应pH4.5。不同温度保温1h后,测定酶的半失活温度为47.7℃,酶的pH稳定性也进行了研究。     

RESTRICTED GENE FLOW IN A MOVING HYBRID ZONE OF THE NEWTS TRITURUS CRISTATUS AND T. MARMORATUS IN WESTERN FRANCE

Two hybridizing species of newts, Triturus cristatus and T. marmoratus, with overlapping distributions show a parapatric distribution when surveyed in detail. The factors that govern the distribution of cristatus vs. marmoratus in the département (province) of Mayenne in western France are identified as forestation and relief. The parapatric hybrid zone running through Mayenne is narrow but widens to approximately 20 km in an area with mixed habitat. In this area most breeding sites are shared and F₁ hybrids form about 4% of the total population. Analysis of survey data collected about 30 years previously also shows an essentially parapatric distribution. Comparison of past and present distribution maps reveals that cristatus has superseded marmoratus over large areas in the south of Mayenne. An area where marmoratus replaced cristatus also exists, but it is more limited in size. Gene flow between cristatus and marmoratus is analyzed using 10 diagnostic genetic markers [9 protein loci and mitochondrial (mt) DNA]. In syntopic populations nuclear gene flow is bidirectional with a mean frequency of introgressed alleles (f) of 0.3%. In allotopic populations of cristatus and marmoratus gene flow is present in areas of species replacement (f = 0.3%), while gene flow appears to be absent in those areas that have been continuously occupied by a single species. At the biogeographic level, the presence or absence of introgression is paralleled by the persistence or absence, respectively, of pockets of cristatus–marmoratus syntopy. All F₁ hybrids possess the cristatus type mtDNA. This may be due to asymmetric interspecific mate choice and would explain the observed absence of introgression of the maternally inherited mtDNA genome in areas where cristatus replaced marmoratus. The cristatus–marmoratus hybrid zone bears characteristics of both the clinal (parapatric) hybrid zone model and the mosaic hybrid zone model. Such a mixed model—for which we propose the term “reticulate hybrid zone”—can be appreciated only if studied over a two-dimensional geographic area and also through time.     

木霉菌株T6木聚糖酶固态发酵条件和酶学性质研究*

研究了碳源和氮源、起始pH、接种量及温度等条件对一野生型木霉Trichoderma sp.T6菌株固态发酵产木聚糖酶的影响。在28℃培养4d后,酶活力可达1918IU/g干培养物。酶的最适反应温度为50℃,最适反应pH4.5。不同温度保温1h后,测定酶的半失活温度为47.7℃,酶的pH稳定性也进行了研究。