Inheritacne of submergence tolerance in rice

Summary Inheritance of submergence tolerance in rice (Oryza sativa L.) was investigated in an 8×8 diallel cross. Duration to 50% mortality of the diallel populations (F₁'s + parents) under completely submerged conditions at the seedling stage was used to characterize submergence tolerance instead of the usual submergence survival percentages.A strong prepotency of parents was found in transmitting the character to their offspring. Additive and nonadditive gene effects were highly significant. Parents highly tolerant to submergence also had high gca effects, and F₁'s between two tolerant parents were found to be the most tolerant of the diallel combinations. A high narrow-sense heritability was also observed.The additive-dominance model was found valid for this diallel cross. Submergence tolerance was partially dominant over susceptibility and recessive alleles were more concentrated in the susceptible parents IR42 and IR11288-B-B-69-1.     

Tomato: a crop species amenable to improvement by cellular and molecular methods

Summary Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures.In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.     

Productivity is a poor predictor of plant species richness

For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters(-2)) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.     

The hexobarbital sleeping time in a pharmacologico-toxicological experiment with special reference to age and chronobiologically-limited variations in Wistar rat strain WIST/Lppt]

Investigations were performed to determine the hexobarbital sleeping time (HST) of a strain of Wistar rats (WIST/Lppt). Another aim of the studies was to demonstrate possibilities to use the HST as a method to get additional informations during pharmacological and toxicological experiments. The age--and sex--dependent changes in the hexobarbital sleeping time of the investigated strain of rats are in coincidence with results of other authors, using different rat strains. Additionally, the HST more or less depends on circadian and circannual rhythm. It was stated that the HST as a prescreening-method before starting investigations in detail is of great importance.     

Development of cell content and shedding of Prototheca spp. in milk from infected udder quarters of cows

It was the objective of this study to analyse shedding patterns and somatic cell counts in cows and quarters infected with Prototheca spp. and to evaluate two approaches to identify infected animals by somatic cell count (SCC) or by bacteriological analysis of pooled milk samples. Five lactating dairy cows, chronically infected with Prototheca spp. in at least one quarter were studied over 11 weeks to 13 months. Quarter milk samples and a pooled milk sample from 4 quarters were collected aseptically from all quarters of the cows on a weekly basis. Culture results of quarter milk and pooled samples were compared using cross tabulation. SCC of quarter milk samples and of pooled samples were related to the probability of detection in the infected quarters and cows, respectively. Shedding of Prototheca spp. was continuous in 2 of 8 quarters. In the other quarters negative samples were obtained sporadically or over a longer period (1 quarter). Overall, Prototheca spp. were isolated from 83.6% of quarter milk samples and 77.0% of pooled milk samples of infected quarters and cows. Somatic cell counts were higher in those samples from infected quarters that contained the algae than in negative samples (p < 0.0001). The same applied for composite samples from infected cows. Positive samples had higher SCC than negative samples. However, Prototheca spp. were also isolated from quarter milk and pooled samples with physiological SCC (i.e. < 10(5)/ml). Infected quarters that were dried off did not develop acute mastitis. However, drying off had no effect on the infection, i.e. samples collected at calving or 8 weeks after dry off still contained Prototheca spp. Results indicate that pre-selection of cows to be sampled for Prototheca spp. by SCC and the use of composite samples are probably inadequate in attempts to eradicate the disease. However, due to intermittent shedding of the algae in some cows, single herd sampling using quarter milk samples probably also fails to detect all infected cases. Therefore, continuous monitoring of problem cows with clinical mastitis or increased SCC in herds during eradication programs is recommended.     

Responses to air flow and airborne plant odour in the Colorado beetle

Colorado beetles moved upwind in a wind tunnel. Odour from leaves of potato, nightshade, tomato and bittersweet enhanced the response. The response disappeared after four antennal segments had been amputated. The odour from meadow grass and dandelion repelled the beetles. Beetles 2–3 weeks emerged but not newly emerged beetles were slightly attracted by celerey. In the same wind tunnel, the scent of female beetles attracted males.Samenvatting In een windtunnel werden proeven gedaan over de reactie van Coloradokevers op de geur van diverse planten. In controleproeven werd een positief anemotactische reactie bij de kevers waargenomen, die werd versterkt door de geur van bladeren van aardappel, nachtschade, tomaat en bitterzoet. In beide gevallen verdween de anemotactische reactie na amputatie van 4 leden van de antennae. Gras en paardebloem beïnvloedden het anemotactisch effect in negatieve zin. Selderij bleek enigszins aantrekkelijk te zijn voor kevers van 2–3 weken oud. Met behulp van hetzelfde apparaat werd aangetoond dat de wijfjes een voor de mannetjes aantrekkelijke geur produceren.     

Nutritional management of inherited copper-associated hepatitis in the Labrador retriever

Canine hereditary copper-associated hepatitis is characterized by gradual hepatic copper accumulation eventually leading to liver cirrhosis. Therapy is aimed at creating a negative copper balance with metal chelators, of which d-penicillamine is the most commonly used. d-penicillamine often causes gastro-intestinal side effects and life-long continuous therapy may lead to a deficiency of copper and zinc. The aim of the current study was to investigate the effect of a low-copper, high-zinc diet as an alternative to continuous d-penicillamine treatment for the long-term management of canine copper-associated hepatitis.Sixteen affected Labrador retrievers were followed for a median time period of 19.1 months (range, 5.9–39 months) after being effectively treated with d-penicillamine. The dogs were maintained on a diet containing 1.3 ± 0.3 mg copper/1000 kcal and 64.3 ± 5.9 mg zinc/1000 kcal. Liver biopsies were taken every 6 months for histological evaluation and copper determination. Plasma alanine aminotransferase (ALT) and alkaline phosphatase, as well as serum albumin were determined.Dietary treatment alone was sufficient to maintain hepatic copper concentration below 800 mg/kg dry weight liver in 12 dogs during the study period. Four dogs needed re-treatment with d-penicillamine. ALT activity and albumin concentration were not associated with hepatic copper concentration, but showed a significant association with the stage and grade of hepatitis respectively. In conclusion, a low-copper, high-zinc diet can be a valuable alternative to continuous d-penicillamine administration for long-term management of dogs with copper-associated hepatitis. The copper re-accumulation rate of an individual dog should be considered in the design of a long-term management protocol and in determining re-biopsy intervals.