Studies on the dominant-lethal and fertility effects of the heavy metal compounds methylmercuric hydroxide, mercuric chloride, and cadmium chloride in male and female mice

Dominant-lethal effects of 10 mg/kg methylmercuric hydroxide were studied in male mice from two hybrid stocks and in females from one of these stocks. Two other compounds, mercuric chloride (2 mg/kg) and cadmium chloride (2 mg/kg), were studied only in females for dominant-lethal (in one hybrid stock) and reproductive capacity effects (in two hybrid and one mixed stocks). All compounds were administered in a single intraperitoneal injection. When males of one of the two stocks studied were treated with methylmercuric hydroxide, the females to which they were mated exhibited a slight reduction in the total number of implantations and in the number of living embryos. These reductions were accompanied by a very small increase in the incidence of dead implantations. In females, cadmium chloride had no detectable dominant-lethal or other fertility effects, except superovulation. On the other hand, the two mercury compounds slightly reduced the numbers of implants and living embryos in females subjected to dominant-lethal studies. The two mercury compounds also induced a slight reduction in the long-term reproductive performance of one stock of females. These results and those reported earlier by others, indicate that the mercury compounds studied so far are not potent inducers of dominant-lethal mutations in male and female mice. It is not clear whether the small effects on male or female fertility induced in some cases, particularly the increase in dead implantations and reductions in the number of living embryos, were attributable to dominant-lethal mutations or to nongenetic causes.     

Bau und Entwicklung des menschlichen Pankreas

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Ornithologische Beobachtungen in den Leitha-Auen bei Zurndorf (Burgenland)

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Downscaling indicators of forest habitat structure from national assessments

Downscaling is an important problem because consistent large-area assessments of forest habitat structure, while feasible, are only feasible when using relatively coarse data and indicators. Techniques are needed to enable more detailed and local interpretations of the national statistics. Using the results of national assessments from land-cover maps, this paper demonstrates downscaling in the spatial domain, and in the domain of the habitat model. A moving window device was used to measure structure (habitat amount and connectivity), and those indicators were then analyzed and combined with other information in various ways to illustrate downscaling.     

Estimating Arundo donax shoot biomass

We developed an equation for estimating Arundo donax shoot dry weight from shoot length. The equation, shoot dry weight (g) = 14.254 (standard error = ±0.275) × shoot height² (m), was as effective at explaining a high proportion of total variation in shoot dry weight (R² = 0.90) as more complicated equations containing additional morphometric parameters. Tested against two independent datasets, the equation provided accurate estimates of dry weight for shoots ranging from 0.3 to 7.06 m height (dataset 1, P < 0.0001, R² = 0.87, N = 29; dataset 2, P < 0.0001, R² = 0.82, N = 192). The equation provides aboveground biomass estimates from stem counts and heights more rapidly than harvest methods.