The cytotaxonomy ofEmilia spp. (Asteraceae: Senecioneae) occurring in Brazil

Analysis of several populations in a large part of the distribution area of the genusEmilia in Brazil has revealed only two species: the diploidE. sonchifolia and the tetraploidE. fosbergii. The more widely reportedE. coccinea was not found. They show a karyotype constancy in morphology and chromosome number (2n = 10 and 2n = 20, respectively), C-banding pattern and number of secondary constrictions. Some indications were found thatE. fosbergii may be an allopolyploid and that its ancestors had different genome sizes.     

Production,cross reactivity,and epitope analysis of monoclonal antibodies against rat kidney gamma glutamyltransferase

Eighteen IgGl monoclonal antibodies (blabs) have been produced against gamma-glutamyl transferase (GGT) from rat kidney. They were specific to the light subunit of the enzyme with affinity constants ranging from 0.3 to 7.5 10⁸ M^–1, while they did not react with GGT from other sources i.e. human and pig kidney, rat and guinea pig liver, suggesting species and organ specificity. Two of the blabs (N° 11 and 21) lost their immunoreactivities towards rat kidney GGT in the presence of N-acetyl-neuraminic acid, while immunoreactivities of the other blabs were unchanged. Furthermore, Mabs No 11 and 21 did not react with desialylated rat kidney GGT. These findings suggest that N-acetyl-neuraminic acid is involved in the epitopes recognized by these two Mabs.Abbreviations ELISA enzyme linked immunosorbent assay - GGT gamma-glutamyltransferase - Mab monoclonal antibody - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis     

Octanoylation of the lipoyl domains of the pyruvate dehydrogenase complex in a lipoyl-deficient strain of Escherichia coli

The overexpression of a subgene encoding a hybrid lipoyl domain of the dihydrolipoamide acetyltransferase component of the pyruvate dehydrogenase complex of Escherichia coli has previously been shown to result in the formation of lipoylated and unlipoylated products. Overexpression of the same subgene in a lipoic acid biosynthesis mutant growing under lipoate-deficient conditions has now been shown to produce domains modified by octanoylation as well as unmodified domains. It was concluded from the mass of a lipoyl-binding-site peptide that the modification involves N6-octanoylation of the lysine residue (Lys244) that is normally lipoylated, and this was confirmed by the trypsin-insensitivity of the corresponding Lys244-Ala-245 bond, and the absence of modification in a mutant domain in which Lys244 is replaced by Gln. This novel protein modification raises interesting questions concerning the pathway of lipoic acid biosynthesis and the mechanism of enzyme lipoylation.     

Cartilage proteoglycans. Assembly with hyaluronate and link protein as studied by electron microscopy.

Aggregates formed by the interaction of cartilage proteoglycan monomers and fragments thereof with hyaluronate were studied by electron microscopy by use of rotary shadowing [Wiedemann, Paulsson, Timpl, Engel & Heinegård (1984) Biochem. J. 224, 331-333]. The differences in shape and packing of the proteins bound along the hyaluronate strand in aggregates formed in the presence and in the absence of link protein were examined in detail. The high resolution of the method allowed examination of the involvement in hyaluronate binding of the globular core-protein domains G1, G2 and G3 [Wiedemann, Paulsson, Timpl, Engel & Heinegård (1984) Biochem. J. 224, 331-333; Paulsson, Mörgelin, Wiedemann, Beardmore-Gray, Dunham, Hardingham, Heinegård, Timpl & Engel (1987) Biochem. J. 245, 763-772]. Fragments comprising the globular hyaluronate-binding region G1 form complexes with hyaluronate with an appearance of necklace-like structures, statistically interspaced by free hyaluronate strands. The closest centre-to-centre distance found between adjacent G1 domains was 12 nm. Another fragment comprising the binding region G1 and the adjacent second globular domain G2 attaches to hyaluronate only by one globule. Also, the core protein obtained by chondroitinase digestion of proteoglycan monomer binds only by domain G1, with domain G3 furthest removed from the hyaluronate. Globule G1 shows a statistical distribution along the hyaluronate strands. In contrast, when link protein is added, binding is no longer random, but instead uninterrupted densely packed aggregates are formed.     

Pericentric inversion of chromosome 19 in three families

Summary Pericentric inversion of chromosome 19 has been found in several members of three unrelated families from a restricted geographical region. In one of the families, an additional pericentric inversion of chromosome 9 was observed. Reproductive problems, multiple abortions in two families and a neonatal death in the third, were present. A review of previously described cases is included, and the genetic risk connected with this type of rearrangement is also discussed.     

DR antigen expression on ovarian carcinoma cells does not correlate with their capacity to elicit an autologous proliferative response

Summary Expression of HLA-DR antigens by purified preparations of human ovarian carcinoma cells freshly isolated from surgical specimens was examined in parallel with the capacity of tumor cells to elicit a blastogenic response from autologous lymphocytes in mixed lymphocyte-tumor culture (MLTC) assay. Of 21 tumor preparations, 11 (52%) reacted with monoclonal antibodies 279 and/or 949 specific for a monomorphic determinant of HLA-DR antigens, with heterogeneous positivity, ranging between 30% and 95%. In this series of patients positive MLTC occurred in 8/21 individual experiments. The HLA-DR expression was proportionally similar in tumors giving positive MLTC (4/8=50%) and negative MLTC (7/13=53%). The lack of correlation between DR expression on tumor cells and stimulatory activity in autologous MLTC and the fact that DR-negative tumors could induce lymphocyte stimulation, support the hypothesis that blastogenesis occurs upon recognition of tumor-associated antigens, different from DR molecules, possibly tumor-specific antigens.     

The Salmonella wien virulence plasmid pZM3 carries Tn1935, a multiresistance transposon containing a composite IS1936-kanamycin resistance element

Tn1935, a 23.5-kb transposon mediating resistance to ampicillin, kanamycin, mercury, spectinomycin, and sulfonamide was isolated from pZM3, an IncFIme virulence plasmid from Salmonella wien. Tn1935 possesses the entire sequence of Tn21 and contains two additional DNA segments of 0.95 and 2.7 kb carrying the ampicillin and kanamycin resistance genes, respectively. The latter is part of a composite element since it is flanked by two IS15-like insertion sequences (IS1936) in direct orientation. IS1936 is about 800 bp long and is closely related to IS15 delta, IS26, IS46, IS140, and IS176. Functional analysis of IS1936-mediated cointegrates shows that both insertion sequences are active and able to form cointegrates at the same frequency. Resolution of the cointegrates requires the presence of the host Rec system. The presence of the composite IS1936-element within Tn1935 supports the hypothesis that multidrug resistance transposons evolved by insertion of antibiotic determinants which are themselves transposable.     

Tricyclic Imipramine Modification of the Circadian Rhythms of Hypothalamic Serotonin, its Precursors and Acid Catabolite in Individually Housed Rats

Circadian rhythms of serotonin (5HT), its precursors tryptophan (TP) and 5-hydroxy-tryptophan (5HTP) and its acid catabolite 5-hydroxy-indoleacetic acid (5HIAA), were determined in the hypothalamus of control rats and rats which had been treated continuously with subcutaneous imipramine (10 mg/kg/day) for 2 weeks.

Rats were individually housed and entrained to LD12:12. Controls showed the 5HT and TP peaks in the light and dark periods respectively, as reported in the literature, but no inverted correlation (antiphase) between SHT and 5HIAA rhythms.

Imipramine significantly modified circadian rhythm characteristics: the 5HT acrophase was advanced, that of TP and 5HIAA was delayed. Imipramine also significantly increased hypothalamic SHT and TP concentrations.     

Decline in measles mortality: nutrition,age at infection,or exposure?

The mortality from measles was studied in an urban area of Guinea-Bissau one year before and five years after the introduction of a vaccination programme. The years after the introduction of immunisation saw a decline in mortality among unvaccinated children with measles. This decline occurred despite a lower age at infection and an increasing prevalence of malnourished children. State of nutrition (weight for age) did not affect the outcome of measles infection. The incidence of isolated cases, however, increased in the period after the introduction of measles vaccination. As mortality was lower among these cases, diminished clustering explained some of the reduction in mortality. Comparison between the urban district and a rural area inhabited by the same ethnic group showed a lower age at infection, less clustering of cases, and lower case fatality ratios in the urban area.Endemic transmission of measles in urban districts leads to less clustering of cases, which may help explain the usually lower case fatality ratios in these areas. As measles vaccination increases herd immunity and diminishes clustering of cases, it may reduce mortality even among unvaccinated children who contract the disease.     

Screening of yeasts for production of xylitol fromd-xylose and some factors which affect xylitol yield inCandida guilliermondii

Summary The ability to convertd-xylose to xylitol was screened in 44 yeasts from five genera. All but two of the strains produced some xylitol with varying rates and yields. The best xylitol producers were localized largely in the speciesCandida guilliermondii andC. tropicalis. Factors affecting xylitol production by a selectedC. guilliermondii strain, FTI-20037, were investigated. The results showed that xylitol yield by this strain was affected by the nitrogen source. Yield was highest at 30–35°C, and could be increased with decreasing aeration rate. Using high cell density and a defined medium under aerobic conditions, xylitol yield byC. guilliermondii FTI-20037 from 104 g/ld-xylose was found to be 77.2 g/l. This represented a yield of 81% of the theoretical value, which was computed to be 0.9 mol xylitol per mold-xylose.Issued as NRCC publication No. 28798.