A further 46,XYp- female

A 24-year-old female with a Swyer syndrome phenotype was found to have a 46,X,del (Y) (p11) karyotype. This observation is consistent with the recently confirmed assignment of the testis-determining master gene to the deletion interval 1A of the Y (Page et al., 1987). Otherwise, it illustrates the etiological heterogeneity of the Swyer phenotype and allows to emphasize the de novo origin of XYp-females.     

Extracellular Overflow of Neuroactive Amino Acids During Severe Insulin-Induced Hypoglycemia: In Vivo Dialysis of the Rat Hippocampus

Hypoglycemia-evoked changes in levels of extracellular excitatory and inhibitory amino acids were studied using the microdialysis technique. A newly designed dialysis probe was inserted stereotaxically into the rat hippocampus. Animals were then subjected to insulin-induced hypoglycemia; then blood glucose levels were restored by glucose injections after a 30-min period of isoelectric electroencephalography. Dialysates were collected before, during, and after the isoelectric period. Amino acids in the dialysates were analyzed by liquid chromatography and fluorescence detection following automatic precolumn derivatization with o-phthaldialdehyde. During the isoelectric phase, the concentration of aspartate increased 15-fold, whereas glutamate, gamma-amino-butyric acid, taurine, and phosphoethanolamine levels were elevated three- to sixfold. Smaller increases were observed for nonneuroactive amino acids such as asparagine, alanine, and phenylalanine. In contrast to all other amino acids, the glutamine content was reduced to less than 30% of preisoelectric values. The concentrations of the neuroactive amino acids were restored to normal in the post-isoelectric phase. These data demonstrate that there is an extracellular overflow of neuroactive amino acids, especially aspartate, during severe hypoglycemia.     

Familial inv(2) (p2300q11.2)

A hitherto undescribed inv(2) (p2300q11.2) was found in 2 generations of a family ascertained through a holoprosencephalic liveborn boy with normal karyotype. This inversion, quite probably not related to the child malformations, does not seem neither impair reproductive fitness nor to yield viable recombination aneusomies.     

Evolution of catalytic proteins

Summary It is believed that all present-day organisms descended from a common cellular ancestor. Such a cell must have evolved from more primitive and simpler precursors, but neither their organization nor the route such evolution took are accessible to the molecular techniques available today. We propose a mechanism, based on functional properties of enzymes and the kinetics of growth, which allows us to reconstruct the general course of early enzyme evolution. A precursor cell containing very few multifunctional enzymes with low catalytic activities is shown to lead inevitably to descendants with a large number of differentiated monofunctional enzymes with high turnover numbers. Mutation and natural selection for faster growth are shown to be the only conditions necessary for such a change to have occurred.     

The Electrical Conductivity of Bovine Milk in Mastitis Diagnosis

The electrical conductivity (EC) of milk is mainly a function of the electrolyte concentration in the milk and therefore raised in mastitis. The present investigation was aimed at elaborating, if possible, a diagnostic model for screening purposes based on EC determinations and consistent with the diagnostic procedures and interpretations commonly used in laboratory milk diagnosis in the Nordic countries (Klastrup 1975). According to this diagnosis (here called reference diagnosis) cell numbers above 300,000/ml (cell count or the corresponding CMT-score) in foremilk quarter samples during the main part of the lactation period and significantly above the lowest value on within-udder comparison during late lactation are considered indicative of mastitis and bacteriological examinations are made when called for.     

Distichia acicularis sp. nov. – a new cushion forming Juncaceae from the high Andes of Ecuador

Distichia acicularis is described as a new species of Juncaceae. It occurs in the high Andes of Ecuador between 3200 m and 4200 m above sea level. Its closest relative is D. muscoides Nees & Meyen from which it is distinct through its narrow, linear, mucronate leafblades and its 1–3 mm long auricles at the junction of the leafsheath to the blade.     

Stability of solvent formation in Clostridium acetobutylicum during repeated subculturing

Summary Clostridium acetobutylicum ATCC 824 was submitted to repeated subculturing at 24-hour intervals for 218 days. The organism retained its ability to form solvents, although the fermentation slowly became increasingly acidogenic during the first 200 days. Except for the initial spore inoculum, the cultures were not subjected to heat shocking between the serial transfers. When the inoculum volume was doubled from 3.3% to 6.7% after 200 days of subculturing, the product formation pattern quickly shifted back from acids to primarily butanol. Acetone production also resumed after being undetectable for more than 50 days. The relative formation of acetate and ethanol remained nearly constant throughout the experiments, while the formation of butyrate mirrored that of butanol.     

New taxa and combinations in neotropical Juncus (Juncaceae)

Juncus arequipensis andJ. breviculmis are described as new species, andJ. ramboi subsp.colombianus as a new subspecies.Juncus arcticus Willd. var.mexicanus (Willd.), var.montanus (Engelm.), and var.andicola (Hook.) are proposed as new combinations.     

The Influence of Specific Phospholipids on the Interaction of Hexokinase with the Outer Mitochondrial Membrane

Repeated washing of a brain mitochondrial fraction results in a progressive decrease in the proportion of mitochondrially bound hexokinase that can be solubilized during a subsequent incubation with glucose-6-phosphate (glucose-6-P). Phospholipids removed during the washing procedure can be added back to washed mitochondria, resulting in enhancement of the solubilization by glucose-6-P. Column and thin-layer chromatographic methods have been used to isolate and identify active phospholipids. Additional studies were performed with purified lipids obtained commercially. Both lysophospholipids and acidic phospholipids were active in enhancing solubilization of hexokinase by glucose-6-P. Phospho-inositides, particularly diphosphoinositide, were quite effective, raising the possibility that the actively metabolized phosphoinositides may be involved in regulation of hexokinase binding in vivo.