Anterior segment mesenchymal dysgenesis: Probable linkage to the MNS blood group on chromosome 4

Thirty-seven blood samples were analyzed for linkage from members of a single family with an anterior segment mesenchymal dysgenesis (ASMD1) with variable expressivity affecting members of at least six generations. Maximum-likelihood analysis for linkage between ASMD1 and 14 biochemical and serological markers in the family showed a probable linkage between ASMD1 and the MNS blood group on the long arm of chromosome 4 (Z = 2.36 at a recombination fraction of .09).     

Muscarinic Cholinergic Stimulation of Exogenous Phosphatidylinositol Hydrolysis Is Regulated by Guanine Nucleotides in Rabbit Brain Cortical Membranes

Rabbit brain cortical membranes, which have been extracted with 2 M KCl, hydrolyze exogenously added [3H]phosphatidylinositol [( 3H]PI) in a guanine nucleotide- and carbachol-dependent manner. Both oxotremorine-M and carbachol are full agonists with EC50 values of 8 and 73 microM, respectively. Pirenzepine and atropine inhibit carbachol-stimulated [3H]PI hydrolysis. The hydrolysis-resistant guanine nucleotide analog guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) is the most potent in supporting carbachol-stimulated hydrolysis of PI. There is no effect of carbachol in the absence of guanine nucleotides or in the presence of 100 microM adenosine 5'-O-(3-thiotriphosphate), adenosine-5'-(beta, gamma-imido)triphosphate, or sodium pyrophosphate. Guanylyl-5'-(beta,gamma-imido)triphosphate [Gpp(NH)p] in the presence of carbachol also stimulates PI hydrolysis although much less than that seen with GTP gamma S. GDP and Gpp(NH)p are potent antagonists of the GTP gamma S-dependent carbachol response. Optimal stimulation by carbachol and GTP gamma S was observed at 0.3-1 microM free Ca2+ and 6 mM MgCl2. Limited trypsinization resulted in loss of receptor-regulated PI breakdown and a slight decrease in basal activity. These results demonstrate that phospholipase C hydrolysis of exogenous PI by rabbit cortical membranes may be stimulated by carbachol in a guanine nucleotide-dependent manner.     

Seasonal fluctuations of zooplankton biomass in Lake Xolotlán (Managua)

Seasonal fluctuations of zooplankton biomass (dry weight) were determined during a year in two localities of Lake Xolotlán (Managua). Biomass estimations of the most common species of rotifers, cladocerans and copepods were made. The maximal zooplankton biomass was observed in February–April (dry season) in coincidence with the period of highest phytoplankton abundance. Copepods contributed with 78% and 84% to the mean zooplankton biomass at points 1 and 7, respectively. Cladocera biomass was lowest during most of the year, and it was probably controlled by fish predation. Development of rotifer biomass was more intense during the rainy season, when detritus particles were more abundant. Daily fluctuations of zooplankton biomass were not pronounced.     

Sequence and characterization of Bacillus subtilis CheW.

A Bacillus subtilis open reading frame (ORF) encoding a predicted polypeptide of 156 amino acids was subcloned and sequenced. The polypeptide was found to be homologous to CheW of Escherichia coli, sharing 28.6% amino acid identity. The ORF was verified by using a bacteriophage T7 expression system in E. coli. The gene was inactivated by insertion of a nonpolor chloramphenicol acetyltransferase cassette in its N-terminal region. In the absence of chemoeffectors, the mutant displayed a smooth swimming bias, with some tumbling. The CheW- mutant was defective on swarm plates but was complemented by a plasmid that expressed wild type CheW. Addition of attractant or repellent to the CheW- mutant resulted in transient smooth swimming or tumbling, respectively. However, capillary assays revealed that chemotaxis was substantially impaired in the mutant strain.     

Biotransformation of cycloalkanones: Controlled oxidative and reductive bioconversions by anAcinetobacter species

Summary Culture conditions have been optimised to enable resting cell cultures ofAcinetobacter calcoaceticus NCIMB 9871 to selectively undertake either oxidative or reductive biotransformations of various bicyclic ketones.     

Construction and characterisation of a yeast artificial chromosome library containing three haploid maize genome equivalents

We have constructed a yeast artificial chromosome (YAC) library using high-molecular-weight DNA prepared from agarose-embedded leaf protoplasts of the maize inbred line UE95. This library contains 79 000 clones with an average insert size of 145 kb and should therefore represent approximately three haploid genome equivalents. The library is organised as an ordered array in duplicate microtitre plates. Forty-one pools of DNA from 1920 individual clones have been prepared for rapid screening of the library by the polymerase chain reaction (PCR). Using this approach, together with conventional colony hybridisation, we have been able to identify between one and eight positive clones for every probe used.     

Adaptations of Goldner's Masson Trichrome Stain for the Study of Undecalcified Plastic Embedded Bone

Specialized adaptations for application of Goldner's Masson trichrome stain to plastic embedded undecalcified bone specimens are presented. This stain can be used successfully on methyl-glycol methacrylate, glycol methacrylate and Spurr embedded bones. The stain affords the advantage of good cellular staining due to the hematoxylin component with concomitant sharp discrimination of mature bone matrix which stains green, immature new bone matrix which stains red, and calcified cartilage which stains very pale green. Use of red filters during photomicrography aids in bone-osteoid discrimination in black and white photographs.     

Scanning electron microscopy ofMycoplasma pneumoniae on the membrane of individual ciliated tracheal cells

Summary Cell monolayer cultures were prepared from hamster tracheal explants by a collagenase exposure and subsequent incubation in Waymouth’s MAB 87/3 medium. The epithelial outgrowth occurred on glass cover slips. Cilia on the monolayers continued to beat normally after the “parent” explant was removed. Monolayer cultures infected withMycoplasma pneumoniae had significant amounts of attachment. A morphological analysis of the attachment was conducted with scanning electron microscopy. Clusters, cocci, and filaments ofM. pneumoniae all attached to the epithelial cells, but the filaments were especially common. Mycoplasmas were seen in association with both ciliated and nonciliated cell membranes. On ciliated cells, mycoplasmas were on the ciliary strands and on the cell membrane. When located immediately adjacent to or in between cilia, mycoplasmas were oriented vertically with the constricted attachment tip oriented down toward the host cell membrane. When located more than a micron away from the ciliary fibers, mycoplasmas lay horizontally along the epithelial cell membrane. The photographic data suggest that clusters or “sperules” of mycoplasmas may liberate individual mycoplasmas that attach to the cell membrane. It appears that the receptor sites forM. pneumoniae are rather uniformly distributed along the ciliated cell membrane, and are not restricted to the interciliary areas. Electron microscopy was done with the cooperation of Dr. R. Macleod and the staff of the Center for Electron Microscopy at the University of Illinois. Critical editorial review was provided by C. Dayton. This investigation was supported in part by grants to M. G. G. from the National Institute of Allergy and Infectious Diseases (AI 12559) and the National Heart, Lung, and Blood Institute (HL 23806), Bethesda, Maryland.     

The induction of sensitivity to gibberellin in aleurone tissue of developing wheat grains

Aleurone tissue from undried immature developing wheat grains (Triticum aestivum L. cv. Sappo), normally insensitive to gibberellic acid, can be made to respond to the hormone by a series of temperature treatments. Incubation of the de-embryoed grains at temperatures above 27° C for at least 8 h causes the tissue to become sensitive. Prolonged incubation at temperatures below 27° C does not effect a change in sensitivity. In addition to the requirement for exposure to an elevated temperature for a period of several hours the tissue must also subsequently be subjected to a period at a lower temperature for just a few seconds for the response to be observed. Once sensitized, the tissue remains responsive to gibberellic acid for substantial periods of time. Exposure of the tissue to temperatures which induce sensitivity to gibberellic acid also results in an increased leakage of amino acids. It is suggested that the increase in sensitivity to gibberellin requires two separate processes to take place. One could be a homeoviscous adaptation of the cell membranes in response to elevated temperature, the other a subsequent, permanent change in conformation of membrane components.