Assessing pathogenicity of MLH1 variants by co-expression of human MLH1 and PMS2 genes in yeast

<p>Abstract</p> <p>Background</p> <p>Loss of DNA mismatch repair (MMR) in humans, mainly due to mutations in the <it>hMLH1 </it>gene, is linked to hereditary nonpolyposis colorectal cancer (HNPCC). Because not all <it>MLH1 </it>alterations result in loss of MMR function, accurate characterization of variants and their classification in terms of their effect on MMR function is essential for reliable genetic testing and effective treatment. To date, <it>in vivo </it>assays for functional characterization of <it>MLH1 </it>mutations performed in various model systems have used episomal expression of the modified MMR genes. We describe here a novel approach to determine accurately the functional significance of <it>hMLH1 </it>mutations <it>in vivo</it>, based on co-expression of human MLH1 and PMS2 in yeast cells.</p> <p>Methods</p> <p>Yeast <it>MLH1 </it>and <it>PMS1 </it>genes, whose protein products form the MutLα complex, were replaced by human orthologs directly on yeast chromosomes by homologous recombination, and the resulting MMR activity was tested.</p> <p>Results</p> <p>The yeast strain co-expressing hMLH1 and hPMS2 exhibited the same mutation rate as the wild-type. Eight cancer-related <it>MLH1 </it>variants were introduced, using the same approach, into the prepared yeast model, and their effect on MMR function was determined. Five variants (A92P, S93G, I219V, K618R and K618T) were classified as non-pathogenic, whereas variants T117M, Y646C and R659Q were characterized as pathogenic.</p> <p>Conclusion</p> <p>Results of our <it>in vivo </it>yeast-based approach correlate well with clinical data in five out of seven hMLH1 variants and the described model was thus shown to be useful for functional characterization of <it>MLH1 </it>variants in cancer patients found throughout the entire coding region of the gene.</p

The growth rate of ruffe, Gymnocephalus cernuus (L., 1758) in the Szczecin Lagoon, the Odra mouth and Lake D±bie

The otoliths back readings method was applied to test the growth rate of Gymnocephalus cernuus from the three water basins of the Odra estuary area Usability of the von Bertalanfy′s equation and quadratic and cubic polynomials theoretical reading of length and weight growth rate was compared. The weight growth of fish aged two to eight was stated to be very uniform

Grow-out of northern pike (Esox lucius L.) larvae under uncontrolled conditions

Background. This study aimed to determine survival rate, extent of cannibalism, and growth rate of northern pike (Esox lucius L.) larvae fed live zooplankton during a grow-out period, i.e., the time prior to when fish become valuable as stocking material. An attempt was also made to assess the food conversion ratio (FCR) with respect to the natural food applied. Materials and methods. Grow-out operations began with 1-day-old pike larvae and involved experimental in-ground tanks with no artificial aeration, forced water flow, artificial circadian lighting, or temperature control. Differently structured habitats (black polyethylene foil, vascular plants, or plastic netting) were placed in all the tanks to separate larvae and provide cover. Feeding live zooplankton to the larvae began on day 3 and food was administered such that larvae were always surrounded by a zooplankton "cloud." Results. The survival rate during the first- (days 1-7) and second (days 8-27) stage of culture was 92.3% and 95.7%, respectively. Highest survival rates were associated with tanks with polyethylene foil habitats, while lowest survival rates were associated with tanks containing plastic netting. No cannibalism was observed in any tank. During the growout period, the total length of larvae increased by an average of 20.88 mm. Although the length increase observed in the three experimental treatments was similar; the significantly highest (P < 0.01) mean length (32.66 mm) was associated with larvae raised in tanks containing polyethylene foil. Until day 13, the mean weight of the larvae did not differ between the three treatments (P = 0.21). At and beyond day 20, fish kept in tanks equipped with polyethylene foil exhibited higher weight increments and on termination of the experiment the mean individual weight of larvae was significantly higher (P < 0.05) than those of larvae in tanks with vascular plants and plastic netting. The food conversion ratio, calculated for the entire culture period was 4.9. Conclusion. High survival rate of the cultured pike larvae demonstrated the success of pike larvae grow-out under uncontrolled conditions

Maturation and fecundity of mackerel (Scomber scombrus L.) in Northwest Atlantic

Studies were carried out in 1983-1984 on gonad development, sex ratio, and absolute and relative fecundity of mackerel from a pre-spawning concentration in Northwest Atlantic. Relationship between gonad development and fish length and sex was determined. Absolute fecundity varied from about 240 thousand to 1160 thousand eggs and correlated most strictly with the fish length

On some problems of reproduction of ruff, Gymnocephalus cernuus (L., 1758) in the Lake D±bie

Changes in the Lake Dąbie ruff gonad maturity and egg diameter were studied. Absolute and relative fecundity values were calculated. The egg diameter distribution suggests portional spawning. The absolute fecundity was found to range within 13,338-82,233 and was most closely correlated with the total fish weight. No effect of body size, age, and ovary weight on the relative fecundity was found

The stock, size and changes in the growth rate of the Northwest Atlantic mackerel (Scomber scombrus L.) in 1971-1983

The influence of the year class size (in numbers) and a stock biomass on the growth rate of 13 cohorts (1971-1983) of the Northwest Atlantic mackerel were investigated. It has been stated that the year class size actually influenced the growth of the examined fish only in the first year of life. The stock biomass was strongly correlated with the growth rate during the first and the second years of life. The density-dependent growth in 3-7 years old mackerel was not observed

Characteristics of age and growth of mackerel (Scomber scombrus L.) from Northwest Atlantic

Age of mackerel caught in Northwest Atlantic in 1983-1984 was determined from otoliths. Growth rate was obtained from direct measurements and back calculations. Growth rate differed noticeably between particular year classes as well as sexes

Some data on the biology of common bream, Abramis brama (L., 1758), from the Międzyodrze waters

Growth rate (based on fry length measurements and back calculations), condition, relative gonad size, and length at first maturity were determined in the common bream population inhabiting Międzyodrze, a deltaic area situated in the vicinity of Szczecin