Regulation of eurotium repens reproduction and secondary metabolite production

Eurotium repens [Anamorph Aspergillus repens] was isolated 1 from spoiled fruit. It reproduced sexually at different sucrose concentrations up to 50% [w/v]; water activity, 0.79. It reproduced asexually at high sucrose concentration 60% [w/v] water activity, 0.75. The concentrations of all detected amino acids were higher in the teleomorph than the anamorph except that of glycine, while alpha aminoadipic acid and alanine were detected in teleomorph only. The extracellular secondary metabolites produced by the teleomorph and anamorph stages were variable and different except epoxysuccinic acid and 2-pyruvylamino benzamide which were produced by the two stages. Glycine, arginine and calcium chloride unlike glutamic acid, aspartic acid and alanine, plays an important role in the induction of teleomorph stage formation at high sucrose concentration 60% [w/v]

Descrição histológica da via genital masculina e hermafrodita de escargots das espécies Achatina fulica E Achatina monochromatica / Histology description of the male and hermafrodite genital vias of the escargots Achatina fulica AND Achatina monochromatica

O objetivo deste trabalho foi descrever a histologia da via genital masculina e hermafrodita dos escargots das espécies Achatina fulica e Achatina monochromatica. Foram usados 10 exemplares adultos de cada espécie para análise histológica. Após o processo seletivo, pesagem e tomada das medidas da concha, os espécimes foram sacrificados por congelamento em freezer, a -2ºC por aproximadamente 10min. Para a exposição dos órgãos reprodutores foi efetuada uma incisão longitudinal iniciada na extremidade cranial e, acompanhando a torção do corpo, até a extremidade caudal. Cada animal foi dissecado, sobre uma placa de Petri, sob imersão em formol a 10% para melhor preservação dos tecidos. Foram coletados fragmentos representativos de cada segmento do sistema reprodutor e observou-se que a estrutura histológica dos mesmos não apresentou diferenças notórias, com exceção do ovotestis do Achatina fulica, no qual se constatou um número maior de células pigmentadas no epitélio germinativo do que, nesse mesmo epitélio, no Achatina monochromatica.

The aim of this work was to make histological description of the male and hermaphrodite genital system of escargots of the species Achatina fulica and Achatina monochromatica. Ten adult copies of each species were used for such analysis. After a selective process, weighting and measuring the shell, the specimens were sacrificed by freezing in freezer to -2ºC for approximately 10min. Reproductive organs were exposed by longitudinal incision made in the cranial extremity and by accompanying the sprain of the body, until the tail extremity. Each animal was dissected over a Petri plate, under immersion in 10% phormol for better preservation of the tissues. Representative fragments of each segment of the reproductive system were collected and it was observed that their histological structure did not present evident differences, except for the Achatina fulica ovotestis in which a larger number of pigmented cells was observed in the germinative epithelium than in the same epithelium in the Achatina monochromatica.

Asexual Recombination in a uvsH Mutant of Aspergillus nidulans

Mutations in the gene uvsH of Aspergillus nidulans result in increased spontaneous chromosome instability and increased intragenic and intergenic mitotic recombination in homozygous diploids. The aim of the present work was to obtain a uvs mutant of A. nidulans and to use it for the isolation of asexual recombinants (parameiotic segregants). The mutant uvsH, named B511, showed normal frequency of meiotic recombination in sexual crosses and high frequency of parameiotic segregants in the parasexual crossings with master strains (B511//A757 and B511//A288). Asexual haploid recombinants (parameiotic segregants), diploid and aneuploid segregants were recovered directly from the uvs//uvs+ heterokaryons (B511//A757 and B511// A288). Parameiotic segregants originated through mitotic crossing-over and independent assortment of chromosomes.

Parasexuality in asexual development mutants of Aspergillus nidulans

The parasexual cycle with parameiosis has been characterized previously by the occurrence of genetic recombination and haploidization inside heterokaryotic hyphae prior to conidial formation. The aim of current research was to characterize, through genetic and cytological analyses, an asexual development mutant strain of A. nidulans and to use it to obtain parameiotic segregants. Analyses showed the medusa phenotype of the B84 strain, whose mutant allele was mapped in the chromosome I. The heterokaryons B84(med)//G422(med+) and B84(med)//G839(brl) were formed in liquid MM+2% CM and inoculated in the appropriate selective media. Two mitotic segregant groups were obtained: aneuploids and haploid stable recombinants. Mitotic segregants, wild-types, and developmental mutants, which did not produce new visible mitotic sectors in the presence of Benomyl and which showed normal meiotic behavior during the sexual cycle, were classified as parameiotics.

Timing of fission in the starfish Allostichaster capensis (Echinodermata: Asteroidea) in laboratory

Timing of fission in the fissiparous starfish Allostichaster capensis under laboratory conditions is described. A. capensis generally splits across the disc along the fission plane during the spring, and then each half regenerates the missing arms during the rest of the year. The fission process can last eight hours. The healing process starts immediately after fission. A. capensis has impressive regeneration ability, including a comet, without signs of disc, regenerated two new arms

Computer simulations for biological aging and sexual reproduction

The sexual version of the Penna model of biological aging, simulated since 1996, is compared here with alternative forms of reproduction as well as with models not involving aging. In particular we want to check how sexual forms of life could have evolved and won over earlier asexual forms hundreds of million years ago. This computer model is based on the mutation-accumulation theory of aging, using bits-strings to represent the genome. Its population dynamics is studied by Monte Carlo methods

Características biológicas de claviceps paspali stev & hall / Biological characteristics of claviceps paspali stev & hall

Se estudia el ciclo biológico de claviceps paspali, un ascomycete parásito, altamente específico de gramíneas del género paspalum (pasto miel). Desarrolla un ciclo asexual (sphacelia deliquescens) en el interior de las flores del pasto miel y uno sexual, en la superficie del suelo. El primero, comienza con la llegada de las ascosporas a la flor, que germina desarrollando un micelio y una secreción melosa muy rica en conidios, con el tiempo ésta se transforma en una masa esclerotial. El segundo se inicia con la germinación del esclerocio, dando 2 a 4 cabezuelas estromáticas, en cuyo interior se encuetran peritecios que contienen ascos con 8 ascosporas, las cuales son expulsadas activamente y los insectos las transportan nuevamente a la flor, cerrándo así el ciclo. La fase asexual es la encargada de la difusión masiva del hongo y la sexual de mantener el hongo viable hasta el verano siguiente