Studies on the binding site of the galactose-specific agglutinin PA-IL from Pseudomonas aeruginosa

The binding properties of Pseudomonas aeruginosa agglutinin-I (PA-IL) with glycoproteins (gps) and polysaccharides were studied by both the biotin/avidin-mediated microtiter plate lectin-binding assay and the inhibition of agglutinin-glycan interaction with sugar ligands. Among 36 glycans tested for binding, PA-IL reacted best with two glycoproteins containing Galalpha1-->4Gal determinants and a human blood group ABO precursor equivalent gp, but this lectin reacted weakly or not at all with A and H active gps or sialylated gps. Among the mammalian disaccharides tested by the inhibition assay, the human blood group Pkactive Galalpha1-->4Gal, was the best. It was 7.4-fold less active than melibiose (Galalpha1-->6Glc). PA-IL has a preference for the alpha-anomer in decreasing order as follows: Galalpha1-->6 >Galalpha1-->4 >Galalpha1-->3. Of the monosaccharides studied, the phenylbeta derivatives of Gal were much better inhibitors than the methylbeta derivative, while only an insignificant difference was found between the Galalpha anomer of methyl- and p -NO2-phenyl derivatives. From these results, it can be concluded that the combining size of the agglutinin is as large as a disaccharide of the alpha-anomer of Gal at nonreducing end and most complementary to Galalpha1-->6Glc. As for the combining site of PA-IL toward the beta-anomer, the size is assumed to be less than that of Gal; carbon-6 in the pyranose form is essential, and hydrophobic interaction is important for binding.      

Ultrastructural aspects of wall regeneration byPythium protoplasts

Electron microscope studies were made of wall regeneration byPythium protoplasts. Wall regeneration began with the formation of a loose network of fibrils on the surface of the protoplast followed by increase in density of the fibrillar mesh and deposition of granular matrix material. The majority of the protoplasts did not develop beyond the loose fibrillar network stage, however a small percentage were able to complete wall formation and to form hyphal tubes. A clear zone of demarcation was visible between the fibrillar surface of the protoplast and the smooth surface at the base of the developing hyphal tube.     

Feline mucopolysaccharidosis VI: purification and characterization of the resident arylsulfatase B activity

Hepatic arylsulfatase B (ASB) from normal and mucopolysaccharidosis VI (MPS VI) cats was purified over 2,800- and 1,800-fold, respectively, and their physical and kinetic properties were characterized. In contrast to the normal feline enzyme, the partially purified MPS VI residual activity had a 100-fold greater Km value and was markedly less stable to thermal, cryo-, and pH-inactivation. In addition, the MPS VI enzyme had a more negative charge as determined by its migration on polyacrylamide gel electrophoresis and its elution profile on cation exchange chromatography. Finally, the MPS VI activity had approximately half the apparent molecular weight of the normal feline enzyme, which was a homodimer, suggesting that the genetic mutation in feline MPS VI altered the subunit association as well as the kinetic and stability properties of the mutant protein.     

Genetics of Somatic Fusion in PHYSARUM POLYCEPHALUM: the Ppii Strain

Plasmodial (somatic) fusion in a strain of Physarum polycephalum, a true slime mold, is controlled by four loci, each of which displays simple dominance. Two diploid plasmodia fuse with each other only if they are phenotypically or genotypically identical for all four fusion loci.     

Inherited XX sex reversal in the cocker spaniel dog

Summary Nine XX true hermaphrodites and two XX males were discovered in a family of American cocker spaniels. The true hermaphrodites were partially-masculinized females with ovotestes; the XX males had malformed male external genitalia and cryptorchid aspermatogenic testes. Wolffian and Mullerian duct derivatives were present in both true hermaphrodites and XX males. All four sires of sex-reversed dogs were normal XY males; five of the dams were anatomically normal females and one was an XX true hermaphrodite. A second true hermaphrodite reproduced as a female, producing anatomically normal offspring.All matings that produced sex-reversed offspring were consanguineous. Matings of the parents of sex-reversed cocker spaniels to normal beagles with no family history of intersexuality produced only normal offspring. Examination of G-banded karyotypes of the affected animals, their parents, and siblings, revealed no structural anomalies of the chromosomes that were consistently associated with sex-reversal.In assays for serologically-detectable H-Y antigen, the group of XX true hermaphrodites and the group of XX males had mean levels of the antigen not significantly different from that in normal male controls. Female parents of sex-reversed dogs and some of their female siblings were typed H-Y antigen positive, but the mean level of the antigen in this group was less than that of normal male controls.It is proposed that XX sex reversal in cocker spaniels is due to a mutant gene which when homozygous in females, results in a level of H-Y antigen similar to that found in normal males and the gonads develop as ovotestes or testes. When the gene is heterozygous in females, the level of serologically-detectable H-Y antigen is lowr than that found in normal males and the gonads develop as normal ovaries. The persistence of Mullerian structures in the presence of testicular tissue suggests that Mullerian inhibiting substance is deficient or ineffective in its action in this condition.Supported by NIH Postdoctoral Fellowship IF32 HL05515, University of Pennsylvania Genetics Center Grant, No. GM 20138, and NIH grants AI-19456, HD 17049, and HD 14357; and a grant from the Mrs. Cheever Porter Foundation.     

Yield and quality of forage maize (<i>Zea mays</i> L.) with different levels of subsurface drip irrigation and plant density

The scarcity of water in arid and semiarid regions of the world is a problem that every day increases by climate change. The subsurface drip irrigation (SDI) and changes in population density of plants are alternatives that can be used to make a sustainable use of water. Therefore, the objectives of this study were to determine the combination that allows for an increased corn performance and efficient use of water without losing the quality of forage. Three different irrigation levels were applied through a system of a SDI at three different densities of forage maize plants in an arid region. The results demonstrated that by applying different levels of water, either enough or lack of soil moisture is created, which is directly reflected in crop yield, and its determining variables such as green forage and dry matter yield, and nutritional quality. The irrigation level to a 100% of potential evapotranspiration (PET), at a density of 80000 plants/ha, increased yield of green forage to 57664 kg/ha; crude protein was 8.59%, while the rest of the quality parameters decreased. This study allowed to conclude that the irrigation level was the major factor in the response of the crop.     

Evidence for vasoactive intestinal polypeptide (VIP) altering the firing rate of preoptic,septal and midbrain central gray neurons

The effect of the iontophoretic application of vasoactive intestinal polypeptide (VIP) on the extracellular electrical activity (neuronal firing rate) of 91 neurons localized in the preoptic (PO), septal (S) region and midbrain central gray (MCG) was studied in urethane-anesthetized female rats. When applied in minute quantities, VIP induced both excitatory ($\text{N = 14}$) and inhibitory ($\text{N = 8}$) changes in the membrane excitability of PO and S neurons (total $\text{N = 58}$), while only inhibitory ($\text{N = 9}$) changes were observed in the MCG neurons (total $\text{N = 33}$; thus 24 MCG neurons were found to be unresponsive to VIP). The latency and duration of the VIP-induced response was, for the most part, characterized by a rapid onset and persisted for the duration of the ejecting pulse. However, five out of the 58 PO and S neurons and one out of the 33 MCG neurons did show responses that were longer and more variable in latency and duration. Of 26 PO neurons recorded and tested with VIP, only five neurons were determined to be antidromically identified (AI) as having their axons in the median eminence. The application of VIP increased the neuronal firing rate in two AI PO neurons, decreased the activity in one, and was ineffective in altering the activity in two other AI PO neurons. The VIP-induced changes in the neuronal firing rate appear to be specific and reproducible, and not related to the ejecting current nor pH of the solution. The results suggest that VIP, a gastrointestinal hormone that is also localized in the brain, can alter the neuronal firing rate of hypothalamic and midbrain neurons, thus providing additional evidence for its possible influence on brain and neuroendocrine function.