Linkage of autosomal recessive lamellar ichthyosis to chromosome 14q.

We have mapped the locus for lamellar ichthyosis (LI), an autosomal recessive skin disease characterized by abnormal cornification of the epidermis. Analysis using both inbred and outbred families manifesting severe LI showed complete linkage to several markers within a 9.3-cM region on chromosome 14q11. Affected individuals in inbred families were also found to have striking homozygosity for markers in this region. Linkage-based genetic counseling and prenatal diagnosis is now available for informative at-risk families. Several transcribed genes have been mapped to the chromosome 14 region containing the LI gene. The transglutaminase 1 gene (TGM1), which encodes one of the enzymes responsible for cross-linking epidermal proteins during formation of the stratum corneum, maps to this interval. The TGM1 locus was completely linked to LI (Z = 9.11), suggesting that TGM1 is a good candidate for further investigation of this disorder. The genes for four serine proteases also map to this region but are expressed only in hematopoietic or mast cells, making them less likely candidates.     

Bioluminescent Salmonella typhimurium provides a rapid assay for measuring the efficacy of freeze-drying suspension media

A strain of Salmonella typhimurium , transformed to a bioluminescent phenotype, was used to compare three freeze-drying suspension media: inositol serum broth with and without added gelatin and sterile skimmed milk. Recovery and growth studies performed by measuring changes in bioluminescence demonstrated that of the three media tested, the routinely used inositol serum broth was the most effective freeze-drying suspension medium.     

Comparison of techniques for measuring plasmid stability in yeasts

Summary Three techniques for measuring plasmid stability in yeasts are described and evaluated. The yeast used was aKluyveromyces lactis strain which was transformed with a plasmid, pCR1, to enable production of heterologous α-amylase. The techniques were based on plate counts on a selective antibiotic-containing medium and a non-selective medium, and on clearing zones on starch-supplemented plates for α-amylase detection. The plate ratio and clearing zones methods gave comparable results while the transfer colony method estimated much lower plasmid stabilities.     

Flight style in bats as predicted from wing morphometry: the effects of specimen preservation

An as yet unconsidered potential error in studies that predict flight style from morphological measurements of bats is the effect of the specimen type employed. On the basis of the finding that morphological measurements taken from fluid-preserved bat specimens may not yield values equivalent to those taken from the live animal, we compared the values of several variables (lifting surface area, wingspan, mass, aspect ratio, wing loading and minimum power speed) for live and fluid-preserved little brown bats ( Myotis lucifugus ) with the accepted standards for this species given by Norberg & Rayner (1987). Significant differences were detected for lifting surface area, wingspan, mass, aspect ratio and wing loading values taken from live bats and their respective values reported by Norberg & Rayner. Differences between preserved bats and Norberg & Rayner's numbers were limited to lifting surface area and wingspan (extended wing positions only), aspect ratio (all wing positions), and mass (both 70% ethanol- and 45% isopropyl alcohol-preserved specimens). Thus, Norberg & Rayner's values correspond most closely to values obtained from preserved museum specimens, a fact reflecting the source of their data in this instance. This and other limitations involved in attempting to predict the flight style of bats from a few morphological characters are discussed.     

Prevalence of headache and migraine in schoolchildren.

OBJECTIVES--To determine the prevalence rates of the various causes of severe headache in schoolchildren, with special emphasis on migraine and its impact on school attendance. DESIGN--Population based study in two stages, comprising an initial screening questionnaire followed by clinical interviews and examination of children with symptoms and a control group of asymptomatic children matched for age and sex. SETTING--67 primary and secondary schools in the city of Aberdeen. SUBJECTS--2165 children, representing a random sample of 10% of schoolchildren in Aberdeen aged 5-15 years. MAIN OUTCOME MEASURES--(a) the prevalence of migraine (International Headache Society criteria) and of other types of headache; (b) the impact of migraine on school attendance. RESULTS--The estimated prevalence rates of migraine and tension headache were 10.6% (95% confidence interval 9.1 to 12.3) and 0.9% (0.5 to 1.5) respectively. The estimated prevalence rates for migraine without aura and migraine with aura were 7.8% (95% confidence interval 6.5 to 9.3) and 2.8% (2.0 to 3.8) respectively. In addition, 10 children (0.7%) had headaches which, though lasting less than two hours, also fulfilled the International Headache Society criteria for migraine, 14 (0.9%) had tension headaches, and 20 (1.3%) had non-specific recurrent headache. The prevalence of migraine increased with age, with male preponderance in children under 12 and female preponderance thereafter. Children with migraine lost a mean of 7.8 school days a year due to all illnesses (2.8 days (range 0-80) due to headache) as compared with a mean of 3.7 days lost by controls. CONCLUSIONS--Migraine is a common cause of headache in children and causes significantly reduced school attendance.     

Analysis of a primer-independent GTF-I from Streptococcus salivarius

Abstract A glucosyltransferase (GTF) gene, designated gtfL , from Streptococcus salivarius was cloned and expressed in Escherichia coli and its nucleotide sequence determined. The GTF-L enzyme catalysed the synthesis of water-insoluble glucan in a primer-independent manner. The nucleotide sequence and derived amino acid sequence of GTF-L were similar in size and domain structure to previously sequenced glucosyltransferases. However, a 464-bp region of high variability was identified which could be selectively amplified from strains of S. salivarius by the polymerase chain reaction and could therefore form the basis for species identification. No sequence-specific motifs related to the solubility and linkage of the glucan product or its need for a dextran primer could be ascertained.     

How does the G protein,Gi2, transduce mitogenic signals?

Serpentine receptors coupled to the heterotrimeric G protein, G_i2, are capable of stimulating DNA synthesis in a variety of cell types. A common feature of the G_i2-coupled stimulation of DNA synthesis is the activation of the mitogen-activated protein kinases (MAPKs). The regulation of MAPK activation by the G_i2-coupled thrombin and acetylcholine muscarinic M₂ receptors occurs by a sequential activation of a network of protein kinases. The MAPK kinase (MEK) which phosphorylates and activates MAPK is also activated by phosphorylation. MEK is phosphorylated and activated by either Raf or MEK kinase (MEKK). Thus, Raf and MEKK converge at MEK to regulate MAPK. G_i2-coupled receptors are capable of activating MEK and MAPK by Raf-dependent and Raf-independent mechanisms. Pertussis toxin catalyzed ADP-ribosylation of α_i2 inhibits both the Raf-dependent and-independent pathways activated by G_i2-coupled receptors. The Raf-dependent pathway involves Ras activation, while the Raf-independent activation of MEK and MAPK does not involve Ras. The Raf-independent activation of MEK and MAPK most likely involves the activation of MEKK. The vertebrate MEKK is homologous to the Ste11 and Byr2 protein kinases in the yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe, respectively. The yeast Ste11 and Byr2 protein kinases are involved in signal transduction cascades initiated by pheromone receptors having a 7 membrane spanning serpentine structure coupled to G proteins. MEKK appears to be conserved in the regulation of G protein-coupled signal pathways in yeast and vertebrates. Raf represents a divergence in vertebrates from the yeast pheromone-responsive protein kinase system. Defining MEKK and Raf as a divergence in the MAPK regulatory network provides a mechanism for differential regulation of this system by G_i2-coupled receptors as well as other receptor systems, including the tyrosine kinases.     

Expression and secretion of wheat α-amylase in Kluyveromyces lactis

The plasmid pCR1 has been constructed to express a wheat -amylase enzyme in Kluyveromyces lactis strains. The contruct is based on the vector pCXJ-kan1, which has been derived from pDK1, a native plasmid of K. lactis var. drosophilarum containing the essential regions for plasmid replication and stability. Contruct pCR1 produces an -amylase by DNA isolated from a wheat cDNA clone and is controlled by a Saccharomyces cerevisia PGK promoter. Correspondence to: C. Russell     

MsmE, a lipoprotein involved in sugar transport in Streptococcus mutans.

Metabolic labelling by [14C]palmitic acid showed that growth of Streptococcus mutans LT11 in raffinose, an inducer of the msm operon, resulted in increased production of a 45-kDa lipoprotein corresponding to MsmE, which is believed to be a sugar-binding protein. MsmE was also labelled when an msmE clone was expressed in Escherichia coli. The presence of a lipid anchor on MsmE provides a likely explanation of how the sugar-binding protein component of the msm binding protein-dependent multiple sugar transport system is retained at the cell surface.