Scanning electron microscopy of Penicillium conidia

The morphology of conidia in 211 species and 12 varieties belonging to the genus Penicillium Link ex Gray have been studied and compared.According to surface ornamentation, conidia have been classified into six groups: A, smooth-walled (7% of the species); B, delicately roughened (13%); C, warty (28%); D, echinate (10%); E, striate with low irregular ridges (36%); and F, striate with scarce high ridges or bars (6%). Whereas the first two groups are closely related in both shape and average size, a gradual reduction was observed in size and in the length/width (l/w) ratio in the remaining groups. Echinate conidia were globose, having the largest average size. Only four species produced conidia not surpassing 2 m in diameter. Maximum length observed was 8 m, and most elongated conidia had a l/w ratio of 3.5. Forty per cent of the species studied had globose conidia.Conidia of the monoverticillate species were generally smaller, more globose and frequently with ridges. In the Asymmetrica, the conidia were generally larger, and showed ridges in comparatively few species. Conidia of the Symmetrica, which were frequently striate with ridges, presented the most elongated forms. The largest average size was found in the conidia of the Polyverticillata which were generally warty. Finally, we have considered the variations in surface ornamentation of conidia during the evolution of the genus Penicillium and drawn attention to their possible relationship with certain habitats and ways of conidial dispersion.     

DNA sequences 3' of the Ig H chain cluster rearrange in mouse B cell lines

A mouse myeloma cell line MPC11 (IgG2b, kappa) and variants derived from it have been used to study DNA rearrangements that occur at the Ig H chain locus. One variant, F5.5, has acquired both VH gene and C epsilon gene rearrangements. Through genomic Southern blot analysis initially directed to mapping the C epsilon gene rearrangement, we observed that the VH region rearrangement was linked, through an inversion event, to sequences that originate 3' of the CH cluster, i.e., 3' of the C alpha gene. Subsequent studies have shown that DNA rearrangements within the region 3' of the C alpha gene are detected in several other mouse myeloma and hybridoma cell lines and are not associated with the expression of specific isotypes.     

Comparison of myosin isoenzymes present in skeletal and cardiac muscles of the Arctic charr Salvelinus alpinus (L.). Sequential expression of different myosin heavy chains during development of the fast white skeletal muscle.

The expression of myosin isoforms and their subunit composition in the white skeletal body musculature of Arctic charr (Salvelinus alpinus) of different ages (from 77-day embryos until about 5 years old) was studied at the protein level by means of electrophoretic techniques. Myosin from the white muscle displayed three types of light chain during all the developmental stages examined: two myosin light chains type 1 (LC1F) differing in both apparent molecular mass and pI, one myosin light chain type 2 (LC2F) and one myosin light chain type 3 (LC3F). The fastest-migrating form of LC1F seemed to be predominant during the embryonic and eleutheroembryonic periods. The slowest-migrating form of LC1F was predominant in the 5-year-old fish. Between 1 year and 4 years, both types of LC1F were present in similar amounts. Cardiac as well as red muscle myosin from 3-year-old fish had two types of light chain. The myosin light chains from atria and ventriculi were indistinguishable by two-dimensional electrophoresis, but were different from the myosin light chains from red muscle. Neither the light chains from cardiac nor red muscle were coexpressed with the myosin light chains of white muscle at any of the developmental stages examined. Two myosin heavy chain bands were resolved by SDS/glycerol/polyacrylamide gel electrophoresis of the extract from embryos. One of the bands was present in minor amounts. The other, and most abundant, band comigrated with the only band found in the extracts of white muscle myosin from older fish. One-dimensional Staphylococcus aureus V8 protease peptide mapping of these bands revealed some differences during development of the white muscle tentatively interpreted as follows. The myosin heavy chain band present in minor amounts in the embryos may represent an early embryonic form that is replaced by a late embryonic or foetal form in the eleutheroembryos. The foetal myosin heavy chain appears to be present until the resorption of the yolk sack and beginning of the free-swimming stage. A new form of myosin heavy chain, termed neonatal and probably expressed around hatching, is present until about 1 year of age.(ABSTRACT TRUNCATED AT 400 WORDS)     

Anabolic actions of a mixed beta-adrenergic agonist on nitrogen retention and protein turnover.

Subcutaneous administration of a mixed beta-agonist induced increases in muscle (+13%) and heart (+17%) weights, which were accompanied by a reduction in back (-13%) and perirenal (-27%) fat stores in young male rats, while no changes in liver were observed. The values of nitrogen retention (mg/day) were significantly higher in the beta-agonist treated animals (+16%) as well as those of muscle DNA content (+8%). On the other hand, no statistically significant changes in muscle protein synthetic activity (g protein synthetized/g RNA) were detected (control: 13.4 vs treated: 14.6), while muscle proteolytic activity was decreased (-9%) in those rats administered with the repartitioning agent. In this context, it is suggested that the anabolic effect of metaproterenol should be attributed to a reduction in muscle protein degradation rather than to changes in protein synthesis.     

Differing Neurochemical and Morphological Sequelae of Global Ischemia: Comparison of Single- and Multiple-Insult Paradigms

The purpose of this investigation was to investigate pathomechanisms responsible for the deleterious effects of repeated episodes of brief forebrain ischemia. Halothane-anesthetized male Wistar rats were subjected to either (a) a single 15-min period or (b) three 5-min periods (separated by 1 h) of global forebrain ischemia by bilateral carotid artery occlusions plus hypotension (50 mm Hg), followed by various periods of recirculation. Brain temperature was normothermic throughout. In one series of rats, extracellular levels of glutamate, glycine, and gamma-aminobutyric acid (GABA) were measured in the dorsolateral striatum (n = 6-8 per group) and lateral thalamus (n = 4-6 per group) by microdialysis and HPLC before and during ischemia and during 3-5 h of recirculation. In a parallel series of rats (n = 6 per group), ischemic cell change was quantified at 2 (dark neurons), 24, or 72 h following either single or multiple ischemic insults. A single 15-min ischemic period led to massive glutamate release (13-fold increase; p = 0.001), which returned to normal by 20-30 min of recirculation and remained normal thereafter. By contrast, in rats with three 5-min periods of ischemia, the glutamate level rise with each repeated insult (four- to 4.5-fold; p < or = 0.02) was smaller than that observed during the single 15-min insult, but a late sustained rise (five- to six-fold; p < 0.05) occurred at 2-3 h of recirculation. Brief ischemia-induced elevations of glycine and GABA levels were detected in both the single- and multiple-insult groups, with normalization during recirculation. In contrast, the excitotoxic index, a composite measure of neurotransmitter release ([glutamate] x [glycine]/[GABA]), differed markedly following single versus multiple insults (p = 0.002 by repeated-measures analysis of variance) and increased by seven- to 12-fold (p < 0.05) at 1-3 h following the third insult. The total amount of glutamate released was 3.3-fold higher in the multiple-insult than in the single-insult group (p < 0.02). At 2 h of recirculation, histopathological analysis of dorsolateral striatum showed a significantly greater frequency of dark neurons in the multiple- than in the single-insult group (p < 0.05 by analysis of variance). In the thalamus, a higher frequency of ischemic neurons was seen in the multiple-than in the single-insult group at all intervals studied. Thus, in rats with multiple ischemic insults, accelerated ischemic damage was found in the striatum, and severe ischemic injury was documented in the thalamus.(ABSTRACT TRUNCATED AT 400 WORDS)     

The conserved helicase motifs of the herpes simplex virus type 1 origin-binding protein UL9 are important for function.

The UL9 gene of herpes simplex virus encodes a protein that specifically recognizes sequences within the viral origins of replication and exhibits helicase and DNA-dependent ATPase activities. The specific DNA binding domain of the UL9 protein was localized to the carboxy-terminal one-third of the molecule (H. M. Weir, J. M. Calder, and N. D. Stow, Nucleic Acids Res. 17:1409-1425, 1989). The N-terminal two-thirds of the UL9 gene contains six sequence motifs found in all members of a superfamily of DNA and RNA helicases, suggesting that this region may be important for helicase activity of UL9. In this report, we examined the functional significance of these six motifs for the UL9 protein through the introduction of site-specific mutations resulting in single amino acid substitutions of the most highly conserved residues within each motif. An in vivo complementation test was used to study the effect of each mutation on the function of the UL9 protein in viral DNA replication. In this assay, a mutant UL9 protein expressed from a transfected plasmid is used to complement a replication-deficient null mutant in the UL9 gene for the amplification of herpes simplex virus origin-containing plasmids. Mutations in five of the six conserved motifs inactivated the function of the UL9 protein in viral DNA replication, providing direct evidence for the importance of these conserved motifs. Insertion mutants resulting in the introduction of two alanines at 100-residue intervals in regions outside the conserved motifs were also constructed. Three of the insertion mutations were tolerated, whereas the other five abolished UL9 function. These data indicate that other regions of the protein, in addition to the helicase motifs, are important for function in vivo. Several mutations result in instability of the mutant products, presumably because of conformational changes in the protein. Taken together, these results suggest that UL9 is very sensitive to mutations with respect to both structure and function, perhaps reflecting its multifunctional character.     

A longitudinal study of porcine serological responses to experimental infections with T-1 and T-3 Spanish Trichinella isolates.

Comparison of antibody response and antigen recognition was made by ELISA and western-blot analysis in pig experimental infections by T-1 and T-3 Spanish Trichinella isolates. Two groups of Iberian pigs were experimentally infected with 150 larvae/kg body weight of GM-1 and C-76 Spanish Trichinella isolates as representatives of T-1 and T-3 gene pools respectively. Antibody levels and antigen recognition were measured on days -14, 0, 6, 16, 20, 27, 34, 49, 63 and 82 after infection by ELISA and western-blotting assays. Antibody response against C-76 infection was significantly delayed and lower than against GM-1. The two Trichinella isolates were indistinguishable, however, by western blotting analysis, although recognition of larval antigens was quantitatively higher than adult ones. Interestingly, the principle larval antigenic components recognized by pigs were those recognized by the monoclonal anti-sera NIM-M1. Finally, there were no serological patterns indicative of the stage of infection ("antibody windows") discriminating, for example between early versus late infections.     

Effect of methabenzthiazuron on growth and nitrogenase activity in Vicia faba

The effects of the herbicide methabenzthiazuron (175 and 220 g ha^-1) on vegetative and reproductive growth, nodulation and nitrogenase activity of Vicia faba were studied in the field under Mediterranean conditions. Nitrogenase activity of excised nodules was estimated using the acetylene reduction assay four times during the developmental period. Leaf area index, dry weight and nitrogen content of the different parts of the plants were measured. Methabenzthiazuron-treated plants showed an increase in nodulation, nitrogenase activity and vegetative growth at early pod fill. Methabenzthiazuron also caused an increase in leaf N content and fruits. These were transient effects found during early and mid pot fill. Nevertheless, plants treated with these sublethal doses of herbicide improved seed production and nitrogen content of seeds at harvest time. The stimulatory effect of methabenzthiazuron on N₂ fixation and vegetative growth seems not be related with the transient stimulatory effect on photosynthetic capacity, also caused by the herbicide, since the stimulatory effect on N₂ fixation was apparent during pod fill, when photosynthetic capacity declined and was not modified by methabenzthiazuron.     

Cloning and expression of hepatitis B surface antigen in the yeastKluyveromyces lactis

Summary The gene coding for the major surface antigen of the hepatitis B virus was integrated into the genome ofKluyveromyces lactis and expressed up to levels of 0.4% of the total soluble protein.     

Detection of linkage for heterogeneous disorders by using multipoint linkage analysis.

We have compared the efficiency of the lod score test which assumes heterogeneity (lod2) to the standard lod score test which assumes homogeneity (lod1) when three-point linkage analysis is used in successive map intervals. If it is assumed that a gene located midway between two linked marker loci is responsible for a proportion of disease cases, then the lod1 test loses power relative to the lod2 test, as the proportion of linked families decreases, as the flanking markers are more closely linked, and as more map intervals are tested. Moreover, when multipoint analysis is used, linkage for a disease gene is more likely to be incorrectly excluded from a complete and dense linkage map if true genetic heterogeneity is ignored. We thus conclude that, in general, the lod2 linkage test is more efficient for detecting a true linkage when a complete genetic marker map is screened for a heterogeneous disorder.