The helminth fauna from the common seal (Phoca vitulina vitulina, Linné, 1758) of the Wadden Sea in Lower Saxony. Part 2: Nematodes.

During the seal epidemic in 1988 and the beginning of 1989, 115 common seals found dead on the shores of the Wadden Sea of Lower Saxony were investigated for the presence of nematodes. The lungworm Otostrongylus circumlitus Railliet 1899 was found in 26.1% of the seals, the lungworm Parafilaroides gymnurus Railliet 1899 in 26.9% and the heartworm Dipetalonema spirocauda Leidy 1858 in 32.2% of the seals. In the digestive tract, two anisakid species were found, Pseudoterranova decipiens Mozgovoi 1951 in 87.8% and Contracaecum osculatum Rudolphi 1802 in 10.4% of the seals. Statistical analysis revealed a negative correlation between age of the seals and prevalence and intensity of infestation with the two lungworm species and the heartworms. Adult seals were found not to be infected with Dipetalonema spirocauda and Parafilaroides gymnurus, whereas the prevalence of the two anisakid species increased with increasing age of the seals. Pseudoterranova decipiens was found more often in autumn and winter than in summer. This parasite was more prevalent and had higher worm counts in the eastern part of the Wadden Sea than in the western part. Parafilaroides gymnurus and Dipetalonema spirocauda were found more often in seals with smaller blubber thickness than in well fed seals.     

Progress in breeding interspecific hybrid ryegrasses

Stable hybrids were produced between tetraploid perennial and Italian ryegrasses derived from commercial varieties and germplasm introduced from European collections. Spaced plant characteristics were used to select Fl plants for the production of F2 families which were assessed in small plots for growth and quality traits. Ten of the 19 selected hybrid families were based on perennial ryegrass collected from the Zurich Uplands. The influence of this parental material in improving vegetative growth during early spring, late summer and autumn was demonstrated. Its use in improving feeding value by increasing the water-soluble carbohydrate content of hybrids was also shown. Consequently, selected hybrid varieties based on this new genetic resource showed considerable improvements in seasonal growth and quality over the older hybrid variety Augusta and Italian ryegrass variety RvP.     

Academic research. California sets up three new institutes

Three University of California campuses were chosen last week as sites for a new $900 million program designed to keep the state a world leader in research and to bolster its economy. Each of the three schools will receive $25 million a year for 4 years from the state, with companies and other sources putting up at least twice that amount.     

Hallucinogenic amphetamine selectively destroys brain serotonin nerve terminals

(+/-)-3,4-Methylenedioxyamphetamine (MDA), an amphetamine analog with hallucinogenic activity, produced selective long-lasting reductions in the level of serotonin, the number of serotonin uptake sites, and the concentration of 5-hydroxyindoleacetic acid in rat brain. Morphological studies suggested that these neurochemical deficits were due to serotonin nerve terminal degeneration. These results show that MDA has toxic activity for serotonin neurons in rats and raise the question of whether exposure to MDA and related hallucinogenic amphetamines can produce serotonin neurotoxicity in the human brain.     

Molecular analysis of the hotspot of recombination in the murine major histocompatibility complex

Biological and serological assays have been used to define four subregions for the I region of the major histocompatibility complex (MHC) in the order I-A, I-B, I-J, and I-E. The I-J subregion presumably encodes the I-J polypeptide of the elusive T-cell suppressor factors. Restriction enzyme site polymorphisms and DNA sequence analyses of the I region from four recombinant mouse strains were used to localize the putative I-B and I-J subregions to a 1.0-kilobase (kb) region within the E beta gene. Sequencing this region from E beta clones derived from the two mouse strains: B10.A(3R), I-Jb and B10.A(5R), I-Jk initially used to define the I-J subregion revealed that these regions are identical, hence the distinct I-Jb and I-Jk molecules cannot be encoded by this DNA. In addition, the DNA sequence data also refute the earlier mapping of the I-B subregion. Analysis of the DNA sequences of three parental and four I region recombinants reveals that the recombinant events in three of the recombinant strains occurred within a 1-kb region of DNA, supporting the proposition that a hotspot for recombination exists in the I region. The only striking feature of this hotspot is a tetramer repeat (AGGC)n that shows 80 percent homology to the minisatellite sequence which may facilitate recombination in human chromosomes.     

Path-Coefficient Analysis of Seed Yield Components in Euphorbia lathyris L.

The interrelationships of seed yield components in Euphorbia lathyris L. have been studied by means of path-coefficient analysis. Two of seven components, ‘Number of flowers of primary inflorescence’ and ‘Number of flowers of secondary inflorescences’ proved to be of major importance through direct effects on ‘Total number of fruits’ as indicator of seed yield. Indirect effects generally arc being canalized via the same variables. Selection for seed yield is made possible through the relation between ‘Number of secondary branches’ and ‘Number of flowers of secondary inflorescences’.     

A photogrammetric method for calculating soil bulk density§

Soil bulk density is an important parameter in many research fields. Unfortunately, no single method exists for measuring bulk density for a wide range of soil conditions. We have carried out tests and compared the results of a photogrammetric method for bulk density estimation as a supplement to widely‐used methods (core method, excavation method).The differences between the methods indicate the potential for using photogrammetry as a supplementary application for estimating soil bulk density.