Susceptibility of Legionella pneumophila to Ultraviolet Radiation

Distilled water suspensions of Legionella pneumophila were found to be sensitive to low doses of germicidal ultraviolet radiation.     

A spectroscopic study of metal ion and ligand binding to β-lactamase II

β-Lactamase II has two metal-binding sites. The electronic spectra of Cd(II)- and Co(II)-substituted β-lactamase II have been investigated. It is suggested that a thiol ligand is involved in metal binding at the first site. The stoichiometric dissociation constants for Co(II) binding to β-lactamase II were estimated to be 0.13 and 2.66 mM (pH 6.0, 4°C, 1 M NaCl) by equilibrium dialysis. Competition between Zn(II) and Co(II) for the first metal binding site suggests a value of 0.7 μM (pH 6.0, 30°C, 1 M NaCl) for the dissociation constant o Zn(II).The electronic spectra of the Co(II) enzyme lead to the suggestion that the coordination geometries around the metal ions in the first and second sites are related to those of a distorted tetrahedron and octahedron, respectively.     

The influence of zooplankton food resources on the morphology of the estuarine clupeid Gilchristella aestuarius (Gilchrist, 1914)

Synopsis The body shape of the estuarine clupeidGilchristella aestuarius from the St. Lucia system is different from that of the same species in other estuaries. The morphology ofG. aestuarius is discussed in relation to long term food availability in the St. Lucia system.     

Scanning electron microscopic study of spermatozoa from gossypol-treated rats

Summary Spermatozoa from the cauda epididymidis of gossypol-treated rats exhibit distinctive departures from the morphology of spermatozoa from control rats: wrinkled and disorganized cell membrane in the head and tail regions, cell membrane missing from segments of the tail midpiece and principal piece regions, malformed heads, decapitate spermatozoa, retention of a cytoplasmic droplet at variable loci along tail midpieces, and looped tails. The observations suggest that gossypol exerts its contraceptive effect during spermatocytogenesis and spermiogenesis, including the posttesticular development and maturation of spermatozoa in the epididymis.     

Chemical induction of β-carotene biosynthesis

Marsh white seedless grapefruit were treated with the 2-diethylaminoethanol esters of the following acids: benzoic, phenylacetic, hydrocinnamic, 4-phenylbutyric, 5-phenylvaleric, valeric, hexanoic, heptanoic, octanoic, nonanoic, 5-chlorovaleric, cyclohexanecarboxylic, phenoxyacetic, p-chlorophenoxyacetic, 3-phenoxypropionic, cinnamic and p-chlorocinnamic. Several of these esters, in particular the hexanoate, 4-phenylbutyrate and cinnamate, caused the accumulation of large amounts of β-carotene. The effects of the hexanoate and of 2-phenoxytriethylamine, which causes only lycopene accumulation, were studied as functions of time. The hexanoate caused the rapid accumulation of lycopene during the first day. The amount of lycopene then began to decrease and that of β-carotene increased until, after 14 days, β-carotene was the major pigment. 2-Phenoxytriethylamine caused rapid lycopene accumulation during the first day and a slow steady increase afterwards. Thus, the mode of action of the β-carotene inducers may be similar to that of the lycopene inducers except that the former are probably rapidly hydrolysed by the esterase(s) in the flavedo, so that they no longer inhibit the cyclase(s), and β-carotene is accumulated at the expanse of lycopene.     

Effects of insecticides on acetylene reduction by Azotobacter vinelandii and soybean nodules

Summary Nine organophosphate and carbamate insecticides were tested for effects on ability of Azotobacter vinelandii to reduce acetylene. Only Gardona^R, at higher concentrations, was significantly inhibitory. The same pesticides were tested with soybeans (Glycine max L.). Some minor phytotoxic effects were noted, but there was no inhibition of the ability of the excised nodules of the plants to reduce acetylene.Published with the approval of the Director of the North Dakota Agricultural Experiment Station as Journal Article No. 726. Portion of a thesis presented by the senior author in partial fulfillment of the requirements for the M.S. degree in bacteriology at North Dakota State University.Published with the approval of the Director of the North Dakota Agricultural Experiment Station as Journal Article No. 726. Portion of a thesis presented by the senior author in partial fulfillment of the requirements for the M.S. degree in bacteriology at North Dakota State University.     

Specific adsorption of starch oligosaccharides in the gel phase of starch granules

The gel phase of native starch-granules is penetrable by such low-molecular-weight solutes as oligosaccharides, amino acids, and salts [Lathe and Ruthven, Biochem. J., 62 (1956) 665]. Molecules larger than about 1000 daltons are effectively excluded. Starch oligosaccharides (maltotriose through maltoheptaose and perhaps higher) exhibit anomalous behavior in that they are taken up by the gel phase far in excess of the amount expected on the basis of their molecular size. Adsorption was measured by using radioactive starch oligosaccharides and counting weighed amounts of solution before and after equilibration with starch granules. The measurements were corrected for water sorption by the starch granules and for exclusion effects as ascertained by controls with nonstarch types of oligosaccharides. Maximum adsorption was observed with maltotetraose. The results indicate a specific binding between the starch oligosaccharides and molecular chains in the starch, presumably those chains in the gel phase. We suggest that these chains constitute interbranch regions of branched molecules, or segments of linear molecules in the gel or amorphous phase, the segments being of sufficient length to form a double helix or other association with the linear oligosaccharides.