INHERITANCE of CUCUMBER TOLERANCE TO ZUCCHINI YELLOW MOSAIC VIRUS

Studies were carried out in Brazil to study the inheritance of tolerance to Zucchini yellow mosaic virus (ZYMV) in cucumber cv. Formosa. This cultivar was individually crossed with two cucumber lines from different varietal types (L(b) from a Brazilian type, and L(j) from a Japanese type), both susceptible to the virus. Two experiments, one for each line, were separately carried out, where 6 treatments (parents, generations F1, F2 and F1BC1 for both parents) were evaluated in a randomized block design with 5 repetitions. Cotyledons of 2-week-old cucumber seedlings were inoculated with ZYMV. Only the plants that did not show symptoms up to 63 days post inoculation were considered as tolerant. A chi-square (chi(2)) analysis for assessing segregation from F2 and both F1BC1, led to the conclusion that the tolerance found in cv. Formosa is determined by a recessive gene.

Sulcus vocalis: evidence for autosomal dominant inheritance

We found evidence of autosomal dominant hereditary transmission of sulcus vocalis. Four dysphonic patients from three generations of the same family were submitted to videolaryngoscopic examination (three patients) and to direct laryngoscopy ( one patient) to diagnose the hoarseness. Sulcus vocalis was diagnosed in all four patients. The finding of four affected individuals in three generations, with vertical transmission affecting man and women, is more consistent with autosomal dominant inheritance pattern; it is an etiological model that we propose for the sulcus vocalis in this pedigree.

NORs inheritance analysis in crossings including individuals from two stocks of rainbow trout (Oncorhynchus mykiss)

Silver nitrate staining of rainbow trouts (Oncorhynchus mykiss) chromosomes, for the identification of the nucleolar organizing regions (NORs), revealed that in individuals from Nucleo Experimental de Salmonicultura de Campos do Jordao (Brazil) NORs were located in the long arms of a submetacentric pair while in specimens from Mount Shasta (USA) NORs were located in the short arms of a submetacentric pair. Cytogenetic analysis of the offspring, obtained through artificial crosses including individuals from both stocks, allowed the identification of NORs in two submetacentric chromosomes, one in the short arms and the other in the long arms, confirming the effectiveness of the hybridization process. Complementary results obtained using the FISH technique with 18S and 5S rDNA probes showed that NOR-bearing chromosomes exhibited a cluster of 5S genes located in tandem with the 18S gene cluster in both stocks. The results allow us to suggest that the difference in NOR-bearing chromosomes found between the two stocks is likely to be due to a pericentric inversion involving the chromosome segment where 18S and 5S rDNA genes are located. The presence of ribosomal genes in the long arms of a submetacentric chromosome is apparently a particular characteristic of the rainbow trout stock of Campos do Jordao and might be used as a chromosome marker in studies of controlled crosses in this species.

Supernumerary chromosome inheritance in the curimbata (Prochilodus lineatus) of the Mogi-Guacu River

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inheritance of resistance to powdery mildew in pea and pathogenesis-related aspects

A herança da resistência ao oídio na cultivar de ervilha MK-10 e alguns aspectos histológicos da infecção foram estudados. Para o estudo da herança, as gerações F1, F2, retrocuzamentos e geração F3 de MK-10 com duas populações suscetíveis foram avaliadas. Nas avaliações histológicas observou-se a porcentagem de conídios germinados, porcentagem de conídios que formaram apressório, porcentagem de conídios que estabeleceram colônia e número de haustórios por colônia. Para comparar as razões de segregação obtidas no estudo da herança da resistência, adotou-se o teste do Qui-quadrado (X²) e para os dados das análises histológicas, utilizou-se o teste Tukey a 5% de probabilidade. Concluiu-se que a resistência de MK-10 ao oídio é devida a um par de alelos recessivos e que a resistência é expressa na fase de pré-penetração, completada por uma morte celular localizada pós-penetração, característica da presença do par de alelos recessivos er1er1.

Variances of direct genetic effects, maternal genetic effects, and cytoplasmic inheritance effects for milk yield, fat yield, and fat percentage

Milk yield, fat yield, and fat percentage during the first three lactations were studied using New York Holsteins that were milked twice daily over a 305-d, mature equivalent lactation. Those data were used to estimate variances from direct and maternal genetic effects, cytoplasmic effects, sire by herd interaction, and cow permanent environmental effects. Cytoplasmic line was traced to the last female ancestor using DHI records from 1950 through 1991. Records were 138,869 lactations of 68,063 cows calving from 1980 through 1991. Ten random samples were based on herd code. Samples averaged 4926 dams and 2026 cytoplasmic lines. Model also included herd-year-seasons as fixed effects and genetic covariance for direct-maternal effects. Mean estimates of the effects of maternal genetic variances and direct-maternal covariances, as fractions of phenotypic variances, were 0.008 and 0.007 for milk yield, 0.010 and 0.010 for fat yield, and 0.006 and 0.025 for fat percentage, respectively. Average fractions of variance from cytoplasmic line were 0.011, 0.008, and 0.009 for milk yield, fat yield, and fat percentage. Removal of maternal genetic effects and covariance for maternal direct effects from the model increased the fraction of direct genetic variance by 0.014, 0.021, and 0.046 for milk yield, fat yield, and fat percentage; little change in the fraction was due to cytoplasmic line. Exclusion of cytoplasmic effects from the model increased the ratio of additive direct genetic variance to phenotypic variance by less than 2%. Similarly, when sire by herd interaction was excluded, the ratio of direct genetic variance to phenotypic variance increased 1% or less.

Vertical inheritance and bursts of transposition have shaped the evolution of the BS non-LTR retrotransposon in Drosophila

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mendelian inheritance, linkage and genotypic disequilibrium in microsatellite loci isolated from Hymenaea courbaril (Leguminosae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)