大丽轮枝菌异核体及其后代的形态与致病力变异

以硝酸盐利用缺陷型突变（ｎｉｔ突变）和抗杀菌剂突变两种遗传标记,对大丽轮枝菌（Ｖｅｒｔｉｃｉｌｌｉｕｍｄａｈｌｉａｅ）异核体后代的形态和致病力进行研究,结果表明,菌核型菌株与菌丝型菌株经菌丝融合形成异核体后,菌丝型菌株能恢复形成微菌核,其后代单孢菌落形成微菌核的数量明显低于菌核型亲本,且遗传性状不稳定;随着转代次数的增多,微菌核形成能力的丧失较菌核型亲本菌株快,异核体后代对棉苗的致病力变化较大,一     

大丽轮枝菌异核体及其后代的形态与致病力变异*

以硝酸盐利用缺陷型突变（nit突变）和抗杀菌剂突变两种遗传标记,对大丽轮枝菌（Verticilliumdahliae）异核体后代的形态和致病力进行研究,结果表明,菌核型菌株与菌丝型菌株经菌丝融合形成异核体后,菌丝型菌株能恢复形成微菌核,其后代单孢菌落形成微菌核的数量明显低于菌核型亲本,且遗传性状不稳定;随着转代次数的增多,微菌核形成能力的丧失较菌核型亲本菌株快。异核体后代对棉苗的致病力变化较大,一般均低于致病力强的亲本菌株,或介于两个亲本致病力之间,或与亲本致病力相近。     

大丽轮枝菌异核体及其后代的形态与致病力变异

以硝酸盐利用缺陷型突变（nit突变）和抗杀菌剂突变两种遗传标记,对大丽轮枝菌（Verticilliumdahliae）异核体后代的形态和致病力进行研究,结果表明,菌核型菌株与菌丝型菌株经菌丝融合形成异核体后,菌丝型菌株能恢复形成微菌核,其后代单孢菌落形成微菌核的数量明显低于菌核型亲本,且遗传性状不稳定;随着转代次数的增多,微菌核形成能力的丧失较菌核型亲本菌株快。异核体后代对棉苗的致病力变化较大,一般均低于致病力强的亲本菌株,或介于两个亲本致病力之间,或与亲本致病力相近。     

大丽轮枝菌微菌核形成能力的遗传

带有硝酸盐利用缺陷型遗传标记的大丽轮技菌Verticilliumdahliae黑色菌核型和白色菌丝型菌株在25℃下配对培养,形成野生型融合菌落带,对融合带的分生孢子后代进行遗传分析的结果表明,融合带中的异核体表现不稳定,分布不均匀。微菌核遗传因子可随亲本细胞质在异核体中的运动和交换而发生迁移。     

大丽轮枝菌微菌核形成能力的遗传*

带有硝酸盐利用缺陷型遗传标记的大丽轮技菌Verticilliumdahliae黑色菌核型和白色菌丝型菌株在25℃下配对培养,形成野生型融合菌落带,对融合带的分生孢子后代进行遗传分析的结果表明,融合带中的异核体表现不稳定,分布不均匀。微菌核遗传因子可随亲本细胞质在异核体中的运动和交换而发生迁移。     

大丽轮枝菌微菌核形成能力的遗传

带有硝酸盐利用缺陷型遗传标记的大丽轮枝菌Ｖｅｒｔｉｃｉｌｌｉｕｍ ｄａｈｌｉａｅ黑色菌核型和白色菌丝型菌株在２５℃下配对培养,形成野生型融合菌落带,对融合带的分生孢子后代进行遗传分析的结果表明,融合带中的异核体表现不稳定,分布不均匀。微菌核遗传因子可随亲本细胞质在异核体中的运动和交换而发生迁移。     

粟长蠕孢菌的异核现象及异核体核型比影响因素的研究

本试验通过23株带有遗传标记的粟长蠕孢菌突变菌株,获得生理性状及生长势不同于亲本的异核体。利用营养缺陷型标记菌株研究的结果表明,粟长蠕孢菌异核体的形成及核型成分的变化受选择压力的影响。原生质体检测结果表明,在异核菌丝体中,异核细胞占46.7%,同核细胞占53.3%。分生孢子检测结果表明,只有0.06%的分生孢子保持异核状态。     

胶孢镰刀菌产生串珠镰刀菌素的不稳定性

从陕北克山病病区分离到的两株串珠镰刀菌素产生菌株——胶孢镰刀菌(Fusarium subglutinans Wollenw.et Reinking)陕-6号和2-17号进行单孢分离,分别得到23和19个单孢分离株。这些单孢菌株可分为两种培养型:一种形态上与原始菌株相似,产生串珠镰刀菌素,产色素,具有大、小分生孢子,转管八次产毒量有下降;另一种则不产串珠镰刀菌素和孢子,无色素,后者在二株菌的单孢分离菌中所占比例分别为60.9％和15.8％。由此可见,胶孢镰刀菌产毒稳定性受异核体和该菌单核变异性共同影响。     

粟长孺孢菌的异核现象

本文报道了粟长孺孢的菌(Hetminthosporium setariae)的异核现象。用γ-射线和甲基磺酸乙酯诱变获得的颜色、形态和营养突变株(H8、Hw)可在基本培养基上形成异核体(8W)。其以上各种特性不同于亲本。 8W分离之后的突变株可稳定地传代,混合后仍能形成异核体。从而证实了该菌的异核性。观察并测定了亲本株和异核体的生长率、致病性及产孢能力。粟长孺孢菌(H8)和玉蜀黍长孺孢菌(866·R-8)可形成种间异核体。     

胶孢镰刀菌产生串珠镰刀菌素的不稳定性

从陕北克山病病区分离到的两株串珠镰刀菌素产生菌株－胶孢镰刀菌陕－６号和２－１７号进行单孢分离,分别得到２３和１９个单孢分离株。这些单孢菌株可为两种培养型：一种形态上与原始菌株相似,产生串珠镰刀菌素,产色素,具有大、小分生孢子,转管八次产毒量有下降,另一种则不产串珠镰刀菌素和孢子,无色素,后者在二株菌的单孢分离菌中所占比例分别为６０．９％和１５．８％。由此可见,胶孢镰刀菌产毒稳定性受异核体和该菌单     

Acetylcholine receptor clustering associates with proteoglycan biosynthesis in C2 variant and heterkaryon muscle cells

Several lines of evidence have suggested roles for proteoglycans (PGs) in acetylcholine receptor (AChR) clustering on muscle cells. One line of evidence comes from the correlation between a defect in the biosynthesis of glycosaminoglycans (GAGs), the defining carbohydrates of PGs, and the failure of spontaneous AChR clustering in the S27 cell line, a genetic variant of the C2 muscle cell line. Two approaches were used in the present study to investigate whether GAG and AChR clustering defects are causally linked. First, the formation of AChR clusters was examined in two more variant lines, S11 and S26, also isolated from the C2 muscle cell line on the basis of deficiencies in GAG biosynthesis. S11 and S26, like S27, are also defective in AChR clustering. Ion exchange analysis of the GAGs made by the S11, S26, and S27 lines revealed that the defects in GAG biosynthesis differ between the three lines. Second, heterokaryon myotubes formed between pairs of the GAG defective variants were tested for complementation in both AChR clustering and GAG biosynthesis. AChR clusters were conspicuous on individual heterokaryon myotubes, and GAG biosynthesis was restored to near wild type levels in the heterokaryon cultures. Complementation in GAG biosynthesis corroborates the biochemical data that the relevant mutations in the genetic variants are in different genes and establishes that the defects are not dominant. The consistent correlation between GAG defects and the failure of AChR clustering across three independent genetic variants and the complementary association of GAG biosynthesis with AChR clustering in heterokaryon myotubes argues against a chance association of the two phenotypes and for a causal relationship between PGs and AChR clustering. A prominent chondroitin sulfate peak correlated with AChR clustering in the heterokaryon cultures. This is consistent with earlier results suggesting that chondroitin sulfate in general is required for the spontaneous clustering of AChRs in C2 cultures and further suggests that a particular chondroitin sulfate proteoglycan may be essential for the clustering process. © 1996 John Wiley & Sons, Inc.     

Escape from mating-type incompatibility in bisexual (A + a) Neurospora heterokaryons.

In Neurospora crassa, strains of opposite mating type generally do not form stable heterokaryons because the mating type locus acts as a heterokaryon incompatibility locus. However, when one A and one a strain, having complementing auxotrophic mutants, are placed together on minimal medium, growth may occur, although the growth is generally slow. In this study, escape from such slow growth to that at a wild type or near-wild type rate was observed. The escape cultures are stable heterokaryons, mostly having lost the mating type allele function from one component nucleus, so that the nuclear types are heterokaryon compatible. Either A or a mating type can be lost. This loss of function has been attributed to deletion since only one nuclear type could be recovered in all heterokaryons except one, but deletion spanning adjacent loci has been directly demonstrated in a minority of cases. Alternatively when one component strain is tol and the other tol+ (tol being a recessive mutant suppressing the heterokaryon incompatibility associated with mating type), escape may occur by the deletion or mutation of tol+, also resulting in heterokaryon compatibility. An induction mechanism for escape is speculated upon.     

On the independence of barrage formation and heterokaryon incompatibility in Neurospora crassa

A barrage is a line or zone of demarcation that may develop at the interface where genetically different fungi meet. Barrage formation represents a type of nonself recognition that has often been attributed to the heterokaryon incompatibility system, which limits the co-occurrence of genetically different nuclei in the same cytoplasm during the asexual phase of the life cycle. While the genetic basis of the heterokaryon incompatibility system is well characterized in Neurospora crassa, barrage formation has not been thoroughly investigated. In addition to the previously described Standard Mating Reaction barrage, we identified at least three types of barrage in N. crassa; dark line, clear zone, and raised aggregate of hyphae. Barrage formation in N. crassa was evident only when paired mycelia were genetically different and only when confrontations were carried out on low nutrient growth media. Barrages were observed to occur in some cases between strains that were identical at all major heterokaryon incompatibility (het) loci and the mating-type locus, mat, which acts as a heterokaryon incompatibility locus during the vegetative phase of N. crassa. We also found examples where barrages did not form between strains that had genetic differences at het-6, het-c, and/or mat. Taken together, these results suggest that the genetic control of barrage formation in N. crassa can operate independently from that of heterokaryon incompatibility and mating type. Surprisingly, barrages were not observed to form when wild-collected strains of N. crassa were paired. However, an increase in the frequency of pairings that produced barrages was observed among strains obtained by back-crossing wild strains to laboratory strains, or through successive rounds of inbreeding of wild-derived strains, suggesting the presence in wild strains of genes that suppress barrage.     

Developmentally regulated expression of vascular smooth muscle myosin heavy chain isoforms

Two types of smooth muscle myosin heavy chain (MHC) isoforms, SM1 and SM2, were recently identified to have different carboxyl termini (Nagai, R., Kuro-o, M., Babij, P., and Periasamy, M. (1989) J. Biol. Chem. 264, 9734-9737). SM1 and SM2 are considered to be generated from a single gene through alternative RNA splicing. In this study we investigated expression of vascular MHC isoforms during development in rabbits at the mRNA, protein, and histological levels. In adults, all smooth muscle cells reacted with both anti-SM1 and anti-SM2 antibodies on immunofluorescence, suggesting the coexpression of SM1 and SM2 in a single cell. In fetal and perinatal rabbits, however, only anti-SM1 antibody consistently reacted with smooth muscles. Reactivity with anti-SM2 antibody was negative in the fetal and neonatal blood vessels and gradually increased during 30 days after birth. These developmental changes in SM1 and SM2 expression at the histological level coincided with mRNA expression of each MHC isoform as determined by S1 nuclease mapping, indicating that expression of SM1 and SM2 is controlled at the level of RNA splicing. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of myosin from fetal and perinatal aortas revealed the presence of large amount of SM2. Interestingly, fetal SM2 did not cross-react with our anti-SM2 antibody on immunoblotting. We conclude that expression of SM1 and SM2 are differentially regulated during development and that a third type of MHC isoform may exist in embryonic and perinatal vascular smooth muscles.     

Bacteriophage Typing of Salmonellae. II. New Bacteriophage Typing Scheme

A phage-typing technique for salmonellae is described. One battery of phages was used to type three serotypes of Salmonella, namely, S. typhimurium, S.typhimurium var. copenhagen, and S. heidelberg. In all, 443 S. heidelberg cultures were typed into 22 phage types, 185 S. typhimurium cultures into 35 phage type, and 92 S. typhimurium var. copenhagen cultures into 26 phage types. The stability of the phage types was established by retyping 168 cultures belonging to all three serotypes. The epidemiological significance of the phage types demonstrated was evaluated by comparing phage types obtained from the University of Minnesota and those from the National Animal Disease Laboratory. Further investigation of the S. heidelberg phage types has shown that the cultures represented repeated isolates from the same birds or from a group of birds in the same flock.     

稻恶苗菌异核体三种核型核DNA的RAPD分析

利用RAPD技术,对稻恶苗菌TJ47-26异核体的紫、红、白三种核型(同核体)核DNA进行比较,用80种10bp长的随机引物进行DNA扩增,共检测了基因组中近400个位点,未发现三种核型的基因组间有明显差异,表明紫、红、白三种核型的DNA碱基序列高度相似。由此推测TJ47-26异核体的三种不同核型是来自同一个核的变异体。     

Carotenogenesis in Phycomyces

Time course studies of carotenoid production and of mycelial growth in liquid cultures of Phycomyces blakesleeanus wild type [NRRL 1555 (?)], red mutants C9, C10 and C13 and the heterokaryon C2 * C9 are reported. The ratios of the concentrations of lycopene, γ-carotene and β-carotene in the red mutant C13 and in the heterokaryon C2 * C9 during the growth periods were measured. In these strains the concentration of lycopene is close to its final value after 2 days of growth, at a time at which β-carotene is just beginning to be produced. It is suggested that the β-carotene produced late is possibly synthesized via β-zeacarotene.     

红麻(Hibiscus cannabinus L.)种质资源的鉴定与分类研究

对300份野生红麻和337份栽培红麻的形态学鉴定发现,红麻的茎、叶、花、果等植物学性状的类型多样,差异明显,遗传多样性十分丰富。野生红麻和栽培红麻一样,染色体数为2n=36,同属红麻种（Hibiscus cannabinus L．）;核型有2n=36=32M＋2SM＋2M（SAT）、2n=36=34M＋2M（SAT）和2n=36=32M＋2ST＋2M（SAT）等;综合形态学研究结果,将野生红麻分为普通、多毛、螺旋花和扁圆果4种类型,其中普通型又可分为3个亚类,普通型与栽培红麻亲缘关系最近,并发现红麻存在亚种。栽培红麻可分为9个变种17个类型,其中4个为新发现变种,7个为新发现类型。     

Effect of model sorptive phases on phenanthrene biodegradation: molecular analysis of enrichments and isolates suggests selection based on bioavailability

Reduced bioavailability of nonpolar contaminants due to sorption to natural organic matter is an important factor controlling biodegradation of pollutants in the environment. We established enrichment cultures in which solid organic phases were used to reduce phenanthrene bioavailability to different degrees (R. J. Grosser, M. Friedrich, D. M. Ward, and W. P. Inskeep, Appl. Environ. Microbiol. 66:2695-2702, 2000). Bacteria enriched and isolated from contaminated soils under these conditions were analyzed by denaturing gradient gel electrophoresis (DGGE) and sequencing of PCR-amplified 16S ribosomal DNA segments. Compared to DGGE patterns obtained with enrichment cultures containing sand or no sorptive solid phase, different DGGE patterns were obtained with enrichment cultures containing phenanthrene sorbed to beads of Amberlite IRC-50 (AMB), a weak cation-exchange resin, and especially Biobead SM7 (SM7), a polyacrylic resin that sorbed phenanthrene more strongly. SM7 enrichments selected for mycobacterial phenanthrene mineralizers, whereas AMB enrichments selected for a Burkholderia sp. that degrades phenanthrene. Identical mycobacterial and Burkholderia 16S rRNA sequence segments were found in SM7 and AMB enrichment cultures inoculated with contaminated soil from two geographically distant sites. Other closely related Burkholderia sp. populations, some of which utilized phenanthrene, were detected in sand and control enrichment cultures. Our results are consistent with the hypothesis that different phenanthrene-utilizing bacteria inhabiting the same soils may be adapted to different phenanthrene bioavailabilities.     

Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Molecular Analysis of Enrichments and Isolates Suggests Selection Based on Bioavailability

Reduced bioavailability of nonpolar contaminants due to sorption to natural organic matter is an important factor controlling biodegradation of pollutants in the environment. We established enrichment cultures in which solid organic phases were used to reduce phenanthrene bioavailability to different degrees (R. J. Grosser, M. Friedrich, D. M. Ward, and W. P. Inskeep, Appl. Environ. Microbiol. 66:2695–2702, 2000). Bacteria enriched and isolated from contaminated soils under these conditions were analyzed by denaturing gradient gel electrophoresis (DGGE) and sequencing of PCR-amplified 16S ribosomal DNA segments. Compared to DGGE patterns obtained with enrichment cultures containing sand or no sorptive solid phase, different DGGE patterns were obtained with enrichment cultures containing phenanthrene sorbed to beads of Amberlite IRC-50 (AMB), a weak cation-exchange resin, and especially Biobead SM7 (SM7), a polyacrylic resin that sorbed phenanthrene more strongly. SM7 enrichments selected for mycobacterial phenanthrene mineralizers, whereas AMB enrichments selected for a Burkholderia sp. that degrades phenanthrene. Identical mycobacterial and Burkholderia 16S rRNA sequence segments were found in SM7 and AMB enrichment cultures inoculated with contaminated soil from two geographically distant sites. Other closely related Burkholderia sp. populations, some of which utilized phenanthrene, were detected in sand and control enrichment cultures. Our results are consistent with the hypothesis that different phenanthrene-utilizing bacteria inhabiting the same soils may be adapted to different phenanthrene bioavailabilities.