Candida albicans and three other Candida species contain an elongation factor structurally and functionally analogous to elongation factor 3.

A cell-free poly(U)-dependent translation elongation system from Candida albicans is ATP-dependent due to the presence of an elongation factor 3 (EF3)-like activity. Saccharomyces cerevisiae ribosomes added to a C. albicans postribosomal supernatant (PRS) supported poly(U)-dependent elongation, suggesting that the C. albicans lysate contained a soluble translation factor functionally analogous to the S. cerevisiae translation factor EF-3. The presence of EF-3 in C. albicans was confirmed by Western blotting using an antibody raised against S. cerevisiae EF-3. This antibody was also used to screen a selection of Candida species, all of which possessed EF-3 with molecular mass in the range of 110-130 kDa.     

Nonaspiration fine needle cytology. Application of a new technique to nodular thyroid disease

The basic principle underlying fine needle aspiration (FNA) is the aspiration of cellular material from target masses, often utilizing fairly high suction pressures. The procedure requires a needle and a syringe, advisedly held in a syringe holder, enabling single-handed suction to be exercised. Mastery of the technique is variable, with few operators acquiring consistent skill. A new technique, pioneered in France but essentially unpublicized, eliminates active aspiration, replacing it by the principle of capillary suction of fluid or semifluid material into a thin channel (a fine needle). This nonaspiration sampling method was tested in a consecutive series of 50 solid thyroid nodules. Simultaneously performed conventional FNAs served as controls. Cell samples were cytologically assessed as unsuitable, diagnostic/adequate or diagnostic/superior, without knowledge of the sampling method employed. Diagnostically superior specimens were obtained significantly more frequently by the nonaspiration technique in 36 benign lesions and 13 neoplasms. The method of nonaspiration fine needle cytology ("cytopuncture") is described and illustrated, and the implications for its use in other sites are discussed.     

Effects of phospholipid composition on the metabolism of triacylglycerol, cholesteryl ester and phosphatidylcholine from lipid emulsions injected intravenously in rats

Lipid emulsions were prepared with a similar size and lipid composition to natural lymph chylomicrons, but in which the surface phospholipid was either egg phosphatidylcholine, dioleoyl-, dimyristoyl-, dipalmitoyl- or 1-palmitoyl-2-oleoylphosphatidylcholine (EYPC, DOPC, DMPC, DPPC or POPC). When injected into the bloodstream of conscious rats, the emulsions containing EYPC or POPC were metabolized similarly to natural chylomicrons, consistent with rapid lipoprotein lipase-mediated hydrolysis of triacylglycerols, followed by hepatic uptake of the remnants derived from the emulsions. Phospholipids from the injected emulsions were removed more slowly and became associated with the high-density lipoprotein fractions of the plasma. Emulsions containing DPPC were metabolized differently. Triacylglycerols disappeared very slowly from plasma, indicating lack of hydrolysis by lipoprotein lipase, and phospholipid radioactivity did not transfer to high-density lipoprotein. With emulsions containing DMPC, the plasma removal rates for emulsion triacylglycerols and cholesteryl esters were fast, but phospholipid radioactivity failed to transfer to the high-density lipoprotein fractions of plasma. With DOPC emulsions, clearances were slower than EYPC or POPC emulsions, but transfer to high-density lipoproteins was efficient. Therefore, an unsaturated chain at the glycerol 2-position was necessary for rapid hydrolysis by lipoprotein lipase and for efficient transfer of phospholipids to high-density lipoproteins. With an unsaturated chain at the glycerol 2-position, a saturated chain at the glycerol 1-position optimized the rate of remnant removal from the plasma.     

Holozygosity for sex-linked genes in males of the termiteIncisitermes schwarzi

The termite Incisitermes schwarzi has multiple sex chromosomes that have arisen by repeated translocations between autosomes and previously existing sex chromosomes. Two sex-linked allozyme loci--Acp-1 and Est-3--are holozygous, not hemizygous, in males (the heterogametic sex). Both loci show less than 1% crossing-over between X and Y chromosomes, and alleles of both are in marked disequilibrium with respect to X vs Y linkage. The two loci assort independently in female meiosis, indicating that they lie on different sex chromosomes. But they are tightly linked in male meiosis because of nonrandom assortment of the multiple X and Y chromosomes in males of this species. The findings of holozygosity and strong linkage disequilibrium suggest that differential selection in the two sexes at or near these loci may be responsible for the establishment of the translocations in this species. The existence of active Y-linked alleles also suggests that the translocations may have occurred recently.     

G-11 staining in Turner's syndrome with mos 45,X/46,X,r(?)

Mos 45,X/46,X,r(?) in 4 patients with Turner's syndrome and no signs of virilization, and in one pair of monozygotic twins, one of them with clitoral hypertrophy, was studied using combined cytogenetic techniques and specially G-11 staining for the characterization of the X or Y origin of the rings. In all 6 patients the ring was G-11 positive, attesting its Y origin. Both twins were operated and bilateral streak gonads with a bilateral nodule of testicular tissue were found. Similar small rings were also studied in one patient with mos 46,XX/46,X,r(X) and in one nonvirilized Turner's syndrome patient with a larger ring; in these two cases the ring was G-11 negative. It seems that the small rings occasionally found in Turner's syndrome are more frequently from Y origin and therefore prophylactic gonadectomy should be considered.     

Mixing patterns in Amazon lakes

The diel mixing patterns of two small floodplain lakes, Lago Jacaretinga in the Amazon drainage, and Lago Cristalino in the Rio Negro system, were investigated during both the high-water and low-water states of the Amazon River hydrograph. Measurements included temperature, oxygen, ammonia, phosphate, and chlorophyll. In both lakes thermal stratification developed during the day and was eroded at night. During the low-water period when the lakes were shallow, nocturnal circulation extended to the lake bottom, whereas when the lakes were deeper (greater than about 5 m), circulation did not reach the bottom and an anoxic hypolimnion developed. During the low-water period, percent of oxygen concentrations were relatively high but always less than saturation. Low oxygen concentrations were observed during the high-water period. At all times nocturnal mixing supplied a significant amount of oxygen to the lake ecosystems. Nighttime upward mixing of recycled nitrogen and phosphorus also appeared to be important nutrient sources for algal productivity.     

Unsuccessful induction of low-zone tolerance to bovine serum albumin injected into the subarachnoid space

Introduction of T-dependent antigens into the subarachnoid space (isas) resulted in higher systemic antibody responses in mice than injections into the peritoneal cavity (ip) or other sites commonly used for immunization. Antibody production in isas immunized mice was not increased by treatment with cyclophosphamide (Cy) at doses known to abolish T-suppressor-cell activity, but such treatment increased antibody production in ip immunized mice toward the higher level which was observed in the isas immunized animals. Suppressor cell-dependent low zone tolerance (LZT) to TNP-BSA could not be induced by isas injections of deaggregated BSA (d-BSA). Conversely, mice which were unresponsive to ip injected d-BSA showed consistent systemic antibody responses when the antigen was injected isas. These observations indicate that immune responses initiated within the CNS are associated with relatively ineffective induction of systemic suppressor cell activity.     

High-frequency conversion to a "fluffy" developmental phenotype in Aspergillus spp. by 5-azacytidine treatment: evidence for involvement of a single nuclear gene.

Transient exposure of mycelia from Aspergillus niger and Aspergillus nidulans to the cytidine analog 5-azacytidine, leading to no more than 0.3 to 0.5% substitution for cytosine by 5-azacytosine in A. nidulans DNA, resulted in the conversion of a high fraction of the cell population (more than 20%) to a mitotically and meiotically stable "fluffy" developmental phenotype. The phenotypic variants are characterized by the developmentally timed production of a profuse fluffy network of undifferentiated aerial hyphae that seem to escape signals governing vegetative growth. Genetic analysis with six different fluffy clones reveals that this trait is not cytoplasmically coded, is recessive in heterozygous diploids but codominant in heterokaryons, and exhibits a 1:1 Mendelian segregation pattern upon sexual sporulation of heterozygous diploids. Complementation and mitotic haploidization studies indicated that all variants are affected in the same gene, which can be tentatively located on chromosome VIII of A. nidulans. Molecular analysis to search for modified bases showed that DNA methylation is negligible in in both A. niger and A. nidulans and that no differences could be detected among DNAs from wild-type cells, fluffy clones, or mycelia exposed to 5-azacytidine. It thus appears that high-frequency conversion of fungal mycelia to a stable, variant developmental phenotype by 5-azacytidine is the result of some kind of target action on a single nuclear gene and that this conversion can occur in organisms virtually devoid of DNA methylation.