Über die Induktion der sexuellen Vermehrung und die genotypische Determination der Wuchsform bei Microsporon gypseum (Bodin) Guiart & Grigoraki

Zusammenfassung Die Autoren beschreiben die Technik der Induktion der Cleistothecienentwicklung auf Agarnährböden und fassen die Ergebnisse der Hybridisation von zwei morphologisch verschiedenen Wuchsformen desMicrosporon gypseum (Bodin)Guiart &Grigoraki 1928 sensu lato zusammen. Ein Stamm (phänotypisch incurvata) wurde aus einer mykotischen Läsion des Menschen isoliert und ist mit dem ConidienstadiumNannizzia incurvataStockdale 1961 identisch. Der zweite Stamm (phänotypisch lanogypsea) wurde aus der Erde isoliert und entspricht morphologisch weder dem ConidienstadiumN. incurvataStockd. 1961,N. gypseaStockd. 1963 nochN. fulvaStockd. 1963. Da beide Stämme kompatibel sind, halten die Autoren die Wuchsform lanogypsea für eine morphologische Mutante der ArtN. incurvata.In sieben unabhängigen Hybridisationen wurden insgesamt 3951 Kulturen verfolgt. Mit Hilfe der Mikromanipulationstechnik erhielt man darunter 486 monoascosporische Kulturen. Die Spaltungsverhältnisse wurden durch den X² Test beglaubigt.Die Wuchsform incurvata und lanogypsea wird durch den Mechanismus der Kernvererbung gelenkt. Die Erblichkeit der studierten Wuchsform wird durch die Voraussetzung monofaktorialer Anlage vom Typ der asexuellen Sporulation erklärt. Diese Voraussetzung bestätigten die durchgeführten Kreuzungsversuche.Die spontane Pleomorphie der monoascosporischen Kulturen ohne Segregationserscheinungen bezeugt, daß sie nicht durch den Zustand einfacher Heterokaryose bewirkt wird.

---

Summary The authors of the present paper describe the technique of the induction of production of cleistoteciae in the agar medium and they summarize the results of hybridization of two morphologically different growth forms ofMicrosporon gypseum (Bodin)Guiart &Grigoraki 1928 sensu lato. One strain (phenotype incurvata) has been isolated from a mycotic lesion of man and is identic with the conidial stage ofNannizzia incurvataStockdale 1961. The other strain (phenotype lanogypsea) has been isolated from soil and it does correspond neither morphologically to the conidial stage ofN. incurvataStockdale 1961, nor toN. gypseaStockdale 1963, nor toN. fulvaStockdale 1963. As both strains are compatible, the authors take the growth form lanogypsea for a morphological mutant of the speciesN. incurvata.On the whole 3951 cultures were followed in seven independent hybridisations. Out of this number 486 cultures were monoascosporic and were obtained by means of the micromanipulation technique. The segregation ratio was verified by the X² test.The growth form incurvata and lanogypsea is controlled by the mechanism of nuclear heredity. The inheritance of the growth form is explained by the hypothetic monofactorial allelic basis of the type of asexual sporulation. This presumption has been proved by the hybridisations which had been effectuated.The spontaneous pleomorphism of monoascosporic cultures gives evidence of the fact that pleomorphism is not conditional on the state of simple heterokaryosis, but by mutation.

     

Epistatic gene effects on the yield of the parents of F1, F2, BC1 and BC2 progeny

The genetic analysis of 5 tomato hybrids (Danubius F₁, Luna F₁, Lido F₁, Balkan F₁ and Mi-10 F₁) was made. We produced their F₁, F₂, BC₁ and BC₂ generations and analysed their yield (on the first three flower branches) as well as some of the yield components of tomato fruits (mean fruit weight, mean fruit weight on the first flower branch, fruit length, fruit width, and number of locules). In order to estimate the gene effects, we applied the additive-dominance mode with three and six parameters. Epistatic gene effects were estimated by applying the six-parameter mode (Mather and Jinks 1982). As for yield and yield components, there were significant differences between the mean values of parents and their progeny. On the basis of the investigated genetic parameters, the obtained results suggested that the additive and dominance gene effects prevailed in the yield and yield components (Danubius F₁, Luna F₁, Lido F₁, Mi-10 F₁), whereas epistatic gene effects were excluded. As for the hybrid Balkan F₁, we recorded significant gene effects, both the additive and the dominance ones in the yield inheritance: additive x additive and dominance x dominance (with the negative sign). The estimated values of the epistatic gene effects were the most prominent in inheriting the feature average fruit weight on the first flower branch — additive x dominance gene effects. They represented the most frequent type of the interallele interaction recorded in the investigated hybrids.     

Two copies of bla NDM-1 gene are present in NDM-1 producing Pseudomonas aeruginosa isolates from Serbia

New Delhi metallo-β-lactamase producing Pseudomonas aeruginosa isolates are of special interest since P. aeruginosa is a major cause of nosocomial infections, the treatment of which could now be jeopardized, especially in developing countries. Six additional NDM-1 positive P. aeruginosa clinical isolates belonging to two different genotypes were shown to be plasmid-free. PFGE-hybridization experiments revealed the chromosomal location of the bla _NDM-1 gene. Restriction analysis and hybridization revealed that two copies of the bla _NDM-1 gene are present in the genomes of all tested isolates, as in previously characterized P. aeruginosa MMA83. Moreover, it was shown that increasing imipenem concentration did not have the effect on copy number of the bla _NDM-1 gene in the genome of P. aeruginosa MMA83.     

Detection of a Trimeric Human Immunodeficiency Virus Type 1 Gag Intermediate Is Dependent on Sequences in the Matrix Protein, p17

Previous studies have shown that single amino acid changes in the amino-terminal matrix (MA) domain, p17, of the human immunodeficiency virus type 1 Gag precursor Pr55, can abrogate virion particle assembly. In the three-dimensional structure of MA such mutations lie in a single helix spanning residues 54 to 68, suggesting a key role for this helix in the assembly process. The fundamental nature of this involvement, however, remains poorly understood. In the present study, the essential features of the MA helix required for virus assembly have been investigated through the analysis of a further 15 site-directed mutants. With previous mutants that failed to assemble, residues mapped as critical for assembly were all located on the hydrophobic face of the helix and had a key role in stabilizing the trimeric interface. This implies a role for the MA trimer in virus assembly. We support this interpretation by showing that purified MA is trimeric in solution and that mutations that prevent virus assembly also prevent trimerization. Trimerization in solution was also a property of a larger MA-capsid (CA) Gag molecule, while under the same conditions CA only was a monomer. These data suggest that Gag trimerization driven by the MA domain is an intermediate stage in normal virion assembly and that it relies, in turn, on an MA conformation dependent on the hydrophobic core of the molecule.     

西藏墨脱格当乡野生虎捕食家畜现状与保护建议

曾经在西藏东南的阔叶林中广泛分布的孟加拉虎,目前仅有一个小种群残留在墨脱县境内。2000年5－6月间,在大型家畜遭受野生虎捕食最严重的墨脱县格当乡展开调查,试图寻找减轻虎害的方法。结果表明：1994－1995年虎的捕食率达到最高,对牛和骡马的捕食率分别是17．9％和9．4％;但1996年后,捕食率分别降低到7．8％和1．8％,这可能与1996年当地曾捕杀过一头虎有关。1993－1999年间,全乡牛的数量下降了11％,但骡马数量上升了23％,这是因为当地为增加运输能力而从别处购得骡马。据反映,目前格当乡境内大约有4－5头虎。1997年和1999年,均见母虎和小虎同行,说明该种群尚有繁殖。在抽样的21户居民家中,1999年4月到2000年5月间,66．6％的人家有大型牲畜遭虎捕杀,共损失牛27头,马12匹,而自1993年以来,21户中共有18户（85．8％）,有牲畜被杀记录,共计损失117头。其中对牛的捕食率达19．7％,对马达11．9％,平均每户损失牛1．2头,骡马0．5匹。非法狩猎减少了虎的猎物如野猪、羚牛等的数量,是老虎转向家畜的主要原因之一。虎害已对格当乡群众的经济造成较大负面影响。但格当乡以及周边地区保护着中国最后的野生孟加拉虎种群,为确保虎的长期生存同时减少人－虎冲突,建议改变目前放牧方式,尽可能联合放牧、增加看护;改善放牧地条件,清除牧场周围蕨草丛;减少对羚牛等有蹄类的猎杀,以减少对老虎猎物种群的破坏;对部分家畜移入棚内试行圈养,既保护家畜,又提高乳制品产量和增加农家肥料;实行多种经营方法,建议养一些山羊和家禽;政府应该帮助安置好部分愿意外迁的居民,这样既满足这些居民的需要,同时也减轻对当地野生动物种群的压力。     

Zebrafish genetic models for arrhythmia

Over the last decade the zebrafish has emerged as a major genetic model organism. While stimulated originally by the utility of its transparent embryos for the study of vertebrate organogenesis, the success of the zebrafish was consolidated through multiple genetic screens, sequencing of the fish genome by the Sanger Center, and the advent of extensive genomic resources. In the last few years the potential of the zebrafish for in vivo cell biology, physiology, disease modeling and drug discovery has begun to be realized. This review will highlight work on cardiac electrophysiology, emphasizing the arenas in which the zebrafish complements other in vivo and in vitro models; developmental physiology, large-scale screens, high-throughput disease modeling and drug discovery. Much of this work is at an early stage, and so the focus will be on the general principles, the specific advantages of the zebrafish and on future potential.