An influenza A virus-specific and HLA-DRw8-restricted T cell clone cross-reacting with a transcomplementation product of the HLA-DR2 and DR4 haplotypes

The clone TA10 is a T3+ T4+ T8- proliferative and cytolytic human T cell clone. This clone has been shown to be specific for the hemagglutinin of influenza A Texas virus and restricted by an HLA class II molecule associated with the DRw8-Dw8.1 phenotype. Here we show that TA10 and all of its subclones can also react with eight HLA-DRw8 negative, Epstein-Barr virus (EBV)-transformed cell lines or phytohemagglutinin blasts in the absence of influenza antigens. All of these cell lines are HLA-DR2/DR4 with a classic DR2 long haplotype. The only nonreactive HLA-DR2/DR4 cell line observed bears a DR2 short haplotype. Only heterozygous HLA-DR2/DR4 but not parental DR2 or DR4 EBV-transformed cell lines can be recognized by TA10, indicating that the cross-reacting determinant is a transcomplementation product between HLA-DR2 and HLA-DR4 haplotypes. DR-specific, but not DQ- or DP-specific monoclonal antibodies, inhibit in the proliferation assay and in the chromium release test both the DRw8-Dw8.1-restricted and the anti-DR2/DR4 reactions. These results show that HLA-DR-restricted, anti-viral human T cell clone can evidence cross-reactivity for allospecific class II molecules of the major histocompatibility complex, and human CTL can recognize transcomplementation products of class II HLA genes. In addition, the results suggest that a beta-chain coded for by an HLA-DR gene and associated with an alpha-chain coded for by a still unidentified but possibly HLA-DQ gene constitute this functional transcomplementation product.     

Mechanism of protein salting in and salting out by divalent cation salts: balance between hydration and salt binding

The preferential interactions of proteins with solvent components were studied in concentrated aqueous solutions of the sulfate, acetate, and chloride salts of Mg2+, Ba2+, Ca2+, Mn2+ and Ni2+ [except for CaSO4, BaSO4, Mn-(OAc)2, and Ni(OAc)2], and results were compared with those of the Na+ salts. It was found that, for all the salts, the preferential hydration increased in the order of Cl- less than CH3-COO- less than SO42- regardless of the cationic species used, in agreement with the anionic lyotropic series, and that the same parameter exhibited a tendency to increase in the order of Mn2+, Ni2+ less than Ca2+, Ba2+ less than Mg2+ less than Na+. The salting-out and stabilizing or salting-in and destabilizing effectiveness of the salts were interpreted in terms of the observed preferential interactions. The surface tension increment of salts, which is a major factor responsible for the preferential interactions of the Na+ salts, had no correlation with those of the divalent cation salts. It was shown that the binding of divalent cations to the proteins overcomes the salt exclusion due to the surface tension increase, leading to a decrease in the preferential hydration. In conformity with this mechanism, the preferential interaction of MgCl2 was strongly pH dependent, because of the protein charge-dependent affinity of Mg2+ for proteins, while NaCl showed no pH dependence of the preferential interaction. The proposed mechanism was supported by a strong correlation between the preferential interaction results and the interaction of these salts with the model peptide compound acetyltetraglycine ethyl ester, described by Robinson and Jencks.     

Spore age and coverslip placement affects germination and post-germination development of Colletotrichum dematium var circinans

Spore suspensions from young (10–14 da; young spores) and old (4 mo; old spores) colonies of PColletotrichum dematium var circinans were placed on slides. Coverslips were left off, placed on in the normal manner, or supported on shims. Slides were placed in moist chambers and incubated in light or dark for up to 48 hrs. Germination and post-germination development were studied. Shimming had some beneficial effect on germination, especially for old spores in dark. In general, more germ-tubes and appressoria were produced on spores under shims than spores with other coverslip treatments. By 48 hrs more old spores under shims germinated, and greater numbers of germ-tubes and appressoria were produced than on other old spores under different coverslip treatments. However, numbers produced were lower than those predicted for comparably treated young spores. Spore age, incubation regime, and placement of coverslips did not affect germ-tube initiation. For all treatments more germ-tubes were initiated from spore tops than bottoms or tips. Fewer germ-tubes were initiated from spore centers than other locations on tops and bottoms, and from both tips than one tip. Approximately 26 % of all appressoria were produced sessile. A higher percentage of sessile appressoria were produced on old spores (80 %) than on young spores (20%).     

On the structure and chromosome location of the 72- and 92-kDa human type IV collagenase genes.

The 72- and 92-kDa type IV collagenases are members of a group of secreted zinc metalloproteases. Two members of this family, collagenase and stromelysin, have previously been localized to the long arm of chromosome 11. Here we assign both of the two type IV collagenase genes to human chromosome 16. By sequencing, the 72-kDa gene is shown to consist of 13 exons, 3 more than have been reported for the other members of this gene family. The extra exons encode the amino acids of the fibronectin-like domain which has so far been found in only the 72- and 92-kDa type IV collagenase. The evolutionary relationship among the members of this gene family is discussed.     

Use of EDTA to prevent spontaneous cell-to-cell transformation provides a more accurate estimation of gene transfer frequencies

Summary Spontaneous cell-to-cell transformation between naturally competent bacteria on selective media resulted in an overestimation of the transferability of genetic information. EDTA effectively prevented transformation on selective media whereas DNaseI did not reliably inhibit cell-to-cell transformation. An improved method to estimate gene transfer frequencies is described.     

Regulation of cellular differentiation during Dictyostelium morphogenesis.

In Dictyostelium there are multiple prestalk cell types that have a complex pattern of directed cell movement during slug formation and culmination. Three extracellular signals, cyclic AMP, DIF and ammonia, control cell type differentiation. Recently there has been considerable progress in understanding their modes of action and interaction.     

Steroid glucuronides as male pheromones in the reproduction of the African catfish Clarias gariepinus—a brief review

After ovulation, female African catfish are strongly attracted by the odor of male conspecifics. This attraction depends on the presence of the seminal vesicle, a part of the male reproductive organs. Removal of the seminal vesicle illustrates this fact. A low dose of seminal vesicle fluid, added to the water, appears to be highly attractive for catfish which have ovulated. Fractionation of the fluid and testing of the different fractions shows that steroid glucuronides could be responsible for the attraction. These steroid glucuronides can be identified with gas chromatographic-mass spectrometric analysis. A mixture of glucuronides, prepared to resemble the composition of the seminal vesicle fluid, evokes a dose-dependent attraction. The most potent odorant, observed by measuring electrical responses from the olfactory epithelium and from the olfactory tract appears to be 3α,17α-dihydroxy-5β-pregnan-20-one-3α-glucuronide.     

Collagen type I fibril packing in vivo and in vitro

Reviewed are works concerning the mechanisms of collagen (type I) fibril packing and the influence of macromolecular structure and physicochemical parameters of the medium on the process.     

Neurogenic cholinergic dilation observed in isolated vessels of the skeletal muscles of cats (the caudal femoral artery)

Neuromediated behaviour of feline caudal femoral arteries was studied in vitro. Transmural stimulation of arteries, previously constricted by noradrenaline, caused an up to 58% relaxation of the induced tone. Atropine (10(-5) g/ml) blocked this response by 93%. The removal of endothelium did not affect the magnitude of the response. It is suggested that the caudal femoral artery is an example of a blood vessel which has muscarinic receptors located directly on its smooth muscles.