Isolation of the third capsule-associated gene, CAP60, required for virulence in Cryptococcus neoformans

A polysaccharide capsule is one of the most important virulence factors for the pathogenic fungus Cryptococcus neoformans. We previously characterized two capsule-associated genes, CAP59 and CAP64. To further dissect the molecular mechanism of capsule synthesis, 16 acapsular mutants induced by 4-nitroquinoline-1-oxide were obtained. The acapsular phenotype of one of these mutants was complemented. The cloned gene was designated CAP60, and deletion of this newly described capsule-associated gene resulted in an acapsular phenotype. The proposed 67-kDa Cap60p contains 592 amino acids and appears to have a putative transmembrane domain close to the N terminus. DNA sequence analysis revealed that CAP60 has similarity to CAP59 at the center portion of its coding regions. Contour-clamped homogeneous electric field blot analysis suggested that these two genes are on the same chromosome. CAP60 and CAP59, however, could not be functionally substituted for each other by direct complementation or by domain swap experiments. In addition, CAP60 is closely linked to a gene which is similar to a cellulose growth-specific gene of Agaricus bisporus, CEL1. Immunogold electron microscopy studies of the epitope-tagged CAP60 gene revealed that Cap60p was primarily localized to the nuclear membrane. Animal model studies indicated that CAP60 is essential for virulence. Thus, CAP60 is required for both capsule formation and virulence.     

Heavy metals in the hair of opossum from Palo Verde, Costa Rica

Levels of lead, cadmium, mercury, chromium, and manganese were measured in the hair of opossum (Didelphis virginiana) from Palo Verde, Guanacaste, Costa Rica. This area has some agriculture, but is slated for extensive water development that will increase ecosystem exposure to a variety of agricultural chemicals. Metal levels were generally not intercorrelated except for chromium and lead, chromium and cadmium, and cadmium and lead. There were significant gender differences only for lead and chromium, with the significantly smaller females having higher levels. It is suggested that hair from mammals, particularly abundant ominivores may be useful, bioindicators of environmental quality over a long time period.     

The frequency of disfluencies during phonatory transitions in stuttered and nonstuttered speech

The AA. investigated the frequency of antibodies against Toxoplasma gondii in 426 women with repeated abortions, perinatal mortality and malformed newborns. They showed on the whole a low incidence even if they demonstrated a high incidence (77.7%) of antibodies in women with malformed newborns. The meaning of the observations are briefly discussed.     

INHIBITION AND ACTIVATION OF BARLEY PEPTIDE HYDROLASES II. PEPTIDE HYDROLASES B AND C,AND L-LEUCYL-β-NAPHTHYLAMIDASE

Peptide hydrolase B is inhibited by DIPF and appears to be a “serine esterase” enzyme. Para-chloromercuribenzoate is also inhibitory, but it acts irreversibly and not as a mercaptide former. Dithiothreitol acts irreversibly to inhibit the enzyme and thioglycolate is a weak, reversible inhibitor. Peptide hydrolase C is also inhibited by DIPF, and no consistent indication of metal ion or sulphydryl group involvement was observed. L-leucyl-β-naphthylamidase apears to be a metalloenzyme. It is mildly inhibited by some chelating agents and is stimulated by Ni²⁺ after prior treatment with EDTA. The enzyme is moderately inhibited by PCMPS and exhibits variable responses to different sulphydryl compounds.     

Geochemical signature of contaminated sediment remobilization revealed by spatially resolved X-ray microanalysis of annual rings of Salix nigra

An X-ray microprobe was used to determine the concentration and distribution of Ni, U, and other metals within annual rings of willows (Salix nigra L.) from a former de facto radiological settling basin (Steed Pond; SP) and a depositional environment downstream (Tims Branch; TB) on the Savannah River Site (SRS). Geochemical and historical information about both areas are well documented. Following spillway breaches at SP in 1984 and the early 1990s, TB is inundated with contaminated sediments during storms. Bulk elemental composition of tree cores was determined using ICP-OES. Synchrotron X-rayfluorescence (SXRF) analysis showed that the metal contents of SP and TB cores were an order of magnitude higher than those from a reference site. TB cores were enriched with Ni in 1984 and 1991, corresponding with SP spillway breaches (containing 790 mg kg(-1) Ni in 1991). Cores from SP exhibited an extremely high Ni peak in 1996, approximately 5000 mg kg(-1), even though contaminant levels at SP did not change. The geochemical signature of contaminants recorded in TB annual rings reflected the significant sediment remobilization events consistent with the detailed history of the site, and at concentrations relative to their proximity to the source term. However, physiological processes occurring within impacted trees strongly influence the chronological accuracy of dendroanalysis and must be investigated further.