A survey of dairy effluent management in the south of Chile

A survey was carried out on 55 commercial dairy farms located in the South of Chile during 1995-97. A questionnaire was developed to obtain informed estimates of dairy effluent management on those farms. Information was analysed on an annual basis using a computer spreadsheet linking all the parameters surveyed. In addition, slurry samples were taken for analysis of dry matter content (DM). Herd size varied between 50 and 800 cows per farm. A large proportion of the total volume of effluents produced came from rainfall (46%), dirty water accounted for 29% with only 25% from cow's faeces and urine. The large volume of effluents produced resulted in a reduced storage capacity (on average of 2 months) or more frequent and higher application rates to the field. Only 37% of the farmers knew the application rates of manure and there was a wide range in the quantity used per year (12 m(3)/ha to 300 m(3)/ha). Dairy effluents were applied mainly on grass (71%) throughout the year but, mostly concentrated during the winter and spring time using only surface irrigation system. The total solids contents of effluents was very low, with 62% of the samples being <4% DM. This reflected the large volumes of clean water that the storage tanks received. The information collected has identified problems in effluent management in Chilean dairy farms where research and technology transfer will be necessary to avoid pollution problems.

The impact of genome defense on mobile elements in Microbotryum

Repeat induced point mutation (RIP), a mechanism causing hypermutation of repetitive DNA sequences in fungi, has been described as a ‘genome defense’ which functions to inactivate mobile elements and inhibit their deleterious effects on genome stability. Here we address the interactions between RIP and transposable elements in the Microbotryum violaceum species complex. Ten strains of M. violaceum, most of which belong to different species of the fungus, were all found to contain intragenomic populations of copia-like retrotransposons. Intragenomic DNA sequence variation among the copia-like elements was analyzed for evidence of RIP. Among species with RIP, there was no significant correlation between the frequency of RIP-induced mutations and inferred transposition rate based on diversity. Two strains of M. violaceum, from two different plant species but belonging to the same fungal lineage, contained copia-like elements with very low diversity, as would result from a high transposition rate, and these were also unique in showing no evidence of the hypermutation patterns indicative of the RIP genome defense. In this species, evidence of RIP was also absent from a Class II helitron-like transposable element. However, unexpectedly the absolute repetitive element load was lower than in other strains.

A two-locus forensic match probability for subdivided populations

A two-locus match probability is presented that incorporates the effects of within-subpopulation inbreeding (consanguinity) in addition to population subdivision. The usual practice of calculating multi-locus match probabilities as the product of single-locus probabilities assumes independence between loci. There are a number of population genetics phenomena that can violate this assumption: in addition to consanguinity, which increases homozygosity at all loci simultaneously, gametic disequilibrium will introduce dependence into DNA profiles. However, in forensics the latter problem is usually addressed in part by the careful choice of unlinked loci. Hence, as is conventional, we assume gametic equilibrium here, and focus instead on between-locus dependence due to consanguinity. The resulting match probability formulae are an extension of existing methods in the literature, and are shown to be more conservative than these methods in the case of double homozygote matches. For two-locus profiles involving one or more heterozygous genotypes, results are similar to, or smaller than, the existing approaches.