New host and locality records for two protozoan (Myxosporea, Coccidia) parasites of marine fishes

This is the first report of the myxosporean Ortholinea orientalis from Atlantic herring Clupea harrengus. It infects the kidney tubules and previously was known from Pacific herring Clupea pallasii and navaga Eleginus navaga in the White Sea and North Pacific Ocean. This is also the first report of the coccidian Eimeria raibauti from Norway pout Trisopterus esmarkii. It infects the epithelium of the pyloric ceca and previously was known only from poorcod Trisopterus minutus in the Mediterranean Sea. The new records are both from the northern North Sea.     

Behavior of nursery/peer-reared and mother-reared rhesus monkeys from birth through 2 years of age

The behavior of 8 nursery/peer-reared and 16 mother-only reared rhesus macaques was observed between birth and 5 months of age, with follow-up studies conducted when the animals were 10–21 months old and living in large social groups. Nursery-reared neonates were more awake, active, and irritable than mother-only reared monkeys. From 1 to 5 months of age the nursery/peer-reared animals exhibited a greater variety of behaviors than the mother-only reared infants, which spent the majority of the time in ventral contact with mothers. As juveniles the groups were indistinguishable with the exception of more self-directed behaviors observed in the nursery/peer-reared monkeys. Both rearing conditions, by virtue of their atypicality, imposed restrictions on social development. The behavioral similarity of the juveniles while in the large social group may be a function of maturation or due to the rehabilitative effect of the large social group.     

Detection of novel sequence heterogeneity and haplotypic diversity of HLA class II genes

Nucleic acid sequences of the second exons of HLA-DRB1, –DRB3/4/5, –DQB1, and –DQA1 genes were determined from 43 homozygous cell lines, representing each of the known class II haplotypes, and from 30 unrelated Caucasian subjects, comprising 60 haplotypes. This systematic sequence analysis was undertaken in order to a) determine the existence of sequence microheterogeneity among cell lines which type as identical by methods other than sequencing; b) determine whether direct sequencing of class II genes will identify the presence of more extensive sequence polymorphism at the population level than that identified with other typing methods; c) accurately determine the molecular composition of the known class II haplotypes; and d) study their evolutionary relatedness by maximum parsimony analysis. The identification of seven previously unidentified haplotypes carrying five new allelic amino acid sequences suggests that sequence microheterogeneity at the population level may be more frequent than previously thought. Maximum parsimony analysis of these haplotypes allowed their evolutionary classification and indicates that the higher mutation rate at DRB1 compared to DQB1 loci in most haplotypic groups is inversed in specific haplotype lineages. Furthermore, the extent and localization of gene conversions and point mutations at class II loci in the evolution of these haplotypes is significantly different at each locus. Identification of additional HLA class II molecular microheterogeneity suggests that direct sequence analysis of class II HLA genes can uncover new allelic sequences in the population and may represent a useful alternative to current typing methodologies to study the effects of sequence allelism in organ transplantation.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers M35890 through M35953.     

Expression and stability of amplified genes encoding 5-enolpyruvylshikimate-3-phosphate synthase in glyphosate-tolerant tobacco cells

Two distinct cDNAs for 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) were obtained from a glyphosate-tolerant tobacco cell line. The cDNAs were 89% identical and the predicted sequences of the mature proteins were greater than 83% identical with EPSPS proteins from other plants. Tobacco EPSPS proteins were more similar to those from tomato and petunia than Arabidopsis. One cDNA clone, EPSPS-1, represented a gene that was amplified in glyphosate-tolerant cells, while the gene for EPSPS-2 was unaltered in these cells. Consequently, EPSPS-1 mRNA was more abundant in tolerant than unselected cells, whereas EPSPS-2 mRNA was at relatively constant levels in these cell lines. Exposure of unselected cells and tobacco leaves to glyphosate produced a transient increase in EPSPS mRNA. However, glyphosate-tolerant cells containing amplified copies of EPSPS genes did not show a similar response following exposure to glyphosate. A significant proportion of the EPSPS gene amplification was maintained when tolerant cells were grown in the absence of glyphosate for eight months. Plants regenerated from these cells also contained amplified EPSPS genes.     

Pea lectin is correctly processed,stable and active in leaves of transgenic potato plants

A gene encoding the preproprotein of the pea (Pisum sativum) lectin was expressed in transgenic potato plants using a cauliflower mosaic virus (CaMV) 35S promoter or a tobacco ribulose bisphosphate carboxylase small subunit (ssRubisco) promoter. Presence of the pea lectin to levels greater than 1% of total soluble leaf protein was detected by radioimmunoassay (RIA). The pattern of expression derived from the two promoters was established using both RIA and a squash-blot immunolocalisation technique. Western blotting demonstrated that the preproprotein was correctly processed, generating and subunits that assembled to give an isolectin form observed in pea seeds and roots. It was also found that the haemagglutination activity and specificity of pea lectin synthesised in transgenic potato leaves was comparable to purified lectin from pea cotyledons.     

A comparative assessment of purification techniques for mesophyll protoplasts of Brassica napus L.

The effects of three different general purification protocols have been assessed quantitatively using mesophyll protoplasts of Brassica napus. Within the initial sample two distinct sub-populations were determined. The methods used influenced the ratio of the vacuolated to chloroplastic type protoplast sub-populations. Overall recovery rates of the initial sample varied according to the method used from 38% to 27%, but the relative recovery of the sub-populations varied considerably with a purified ratio of between 1.0:0.78 to 1.0:7.0. Size distribution profiles of the initial and purified populations are also presented.     

Sequence analysis of two exons from the murine dystrophin locus

We have isolated two genomic clones from the murine dystrophin locus, containing single exons encoding protein sequence from the putative actin-binding domain of the amino-terminus and the terminal portion of the triple helical domain. Using interspecific backcross progeny mice, both clones were shown to be X-linked. Sequence analysis indicated that the amino-terminal clone contains a 173 bp exon exhibiting 90% nucleotide sequence identity to human dystrophin exon 6, whilst the C-terminal clone contains a 61 bp exon with 93% nucleotide sequence identity to the human cDNA sequence.

     

Mouse Chromosome 7

Chair of Committee for Mouse Chromosome 7     

Pathfinding by zebrafish motoneurons in the absence of normal pioneer axons.

Individually identified primary motoneurons of the zebrafish embryo pioneer cell-specific peripheral motor nerves. Later, the growth cones of secondary motoneurons extend along pathways pioneered by primary motor axons. To learn whether primary motor axons are required for pathway navigation by secondary motoneurons, we ablated primary motoneurons and examined subsequent pathfinding by the growth cones of secondary motoneurons. We found that ablation of the primary motoneuron that pioneers the ventral nerve delayed ventral nerve formation, but a normal-appearing nerve eventually formed. Therefore, the secondary motoneurons that extend axons in the ventral nerve were able to pioneer that pathway in the absence of the pathway-specific primary motoneuron. In contrast, in the absence of the primary motoneuron that normally pioneers the dorsal nerve, secondary motoneurons did not pioneer a nerve in the normal location, instead they formed dorsal nerves in an atypical position. This difference in the ability of these two groups of motoneurons to pioneer their normal pathways suggests that the guidance rules followed by their growth cones may be very different. Furthermore, the observation that the atypical dorsal nerves formed in a consistent incorrect location suggests that the growth cones of the secondary motoneurons that extend dorsally make hierarchical pathway choices.