Comparison of two lignin-degrading fungi:Phlebia radiata andPhanerochaete chrysosporium

Summary The ligninolytic enzymes ofPhlebia radiata were produced in static conditions earlier developed forPhanerochaete chrysosporium. The production pattern of lignin peroxidases resembled that ofP. chrysosporium. The extracellular proteins ofPhlebia radiata were separated by isoelectric focusing. Four proteins with acidic isoelectric points (4.15) were detected by peroxidase staining. The peroxidases ofP. radiata reacted with antibodies produced against a peroxidase ofPhanerochaete chrysosporium and vice versa. Thus the lignin peroxidases of the two fungi have major similarities despite slight differences in their isoelectric points and molecular weights. Veratryl alcohol was produced by both fungi and degraded to veratraldehyde, two lactones and a quinone by the ligninolytic cultures.     

Energy metabolism,body-temperature and breathing parameters in nontorpid blue-naped mousebirdsUrocolius macrourus

Summary Breathing frequencyF _r of resting blue-naped mousebirdsUrocolius macrourus lies between 50–70 per min and correlates directly with ambient temperatureT _a and energy metabolismM. The nocturnal mean energy intake per breath varies between 5.6–17.7 mJ/g. At highT _a the birds show gular fluttering with a relatively constantF _r of about 460 min^–1.M shows a constant absolute day-night difference of 25 J/g·h; the relative differences areT _a-dependent between 36–168% (lower values at lowerT _a). Thermal conductance is 2.10–2.15 J/g·h·°C (predicted 2.67), indicating a good insulation. Basal metabolic rate BMR is reduced by 63% compared to predicted values. At aT _a-range of +8–36 °C the birds are normothermic. Below this range nocturnalT _b andM decrease slightly with fallingT _a. The birds show partial heterothermia (shallow hypothermia). Clustering is an effective energy saving strategy which allows loweringM with keeping highT _b even at lowT _a.Oxygen-intake is controlled byF _r as well as by tidal volumeV t inT _a-dependent changing portions.V T can vary between 0.29–0.91 ml (mean value 49.7 ml).Abbreviations T _a ambient temperature - T _b body temperature - M energy metabolism - F _r breathing frequency - V T tidal volume - BMR basal metabolic rate - TNP thermoneutral point     

Infectious rotavirus enters cells by direct cell membrane penetration, not by endocytosis.

Rotaviruses are icosahedral viruses with a segmented, double-stranded RNA genome. They are the major cause of severe infantile infectious diarrhea. Rotavirus growth in tissue culture is markedly enhanced by pretreatment of virus with trypsin. Trypsin activation is associated with cleavage of the viral hemagglutinin (viral protein 3 [VP3]; 88 kilodaltons) into two fragments (60 and 28 kilodaltons). The mechanism by which proteolytic cleavage leads to enhanced growth is unknown. Cleavage of VP3 does not alter viral binding to cell monolayers. In previous electron microscopic studies of infected cell cultures, it has been demonstrated that rotavirus particles enter cells by both endocytosis and direct cell membrane penetration. To determine whether trypsin treatment affected rotavirus internalization, we studied the kinetics of entry of infectious rhesus rotavirus (RRV) into MA104 cells. Trypsin-activated RRV was internalized with a half-time of 3 to 5 min, while nonactivated virus disappeared from the cell surface with a half-time of 30 to 50 min. In contrast to trypsin-activated RRV, loss of nonactivated RRV from the cell surface did not result in the appearance of infection, as measured by plaque formation. Endocytosis inhibitors (sodium azide, dinitrophenol) and lysosomotropic agents (ammonium chloride, chloroquine) had a limited effect on the entry of infectious virus into cells. Purified trypsin-activated RRV added to cell monolayers at pH 7.4 medicated 51Cr, [14C]choline, and [3H]inositol released from prelabeled MA104 cells. This release could be specifically blocked by neutralizing antibodies to VP3. These results suggest that MA104 cell infection follows the rapid entry of trypsin-activated RRV by direct cell membrane penetration. Cell membrane penetration of infectious RRV is initiated by trypsin cleavage of VP3. Neutralizing antibodies can inhibit this direct membrane penetration.     

Simultaneous pressure and 19F NMR pH measurements of smooth muscle cells of intact hog carotid arteries at rest and during contractions with norepinephrine

Using 19F NMR we have measured the intracellular pH of the vascular smooth muscle cells of hog carotid arteries at rest and during contractions induced with norepinephrine. Experiments were performed on single, intact arteries closed at both ends, superfused from the lumen and loaded with the 19F NMR pH indicator alpha-difluoromethylalanine. At rest, luminal pressure was maintained at 100 +/- 2 mm Hg and intracellular pH was 7.12 +/- 0.04. Contractions elicited with 10(-5) M norepinephrine were associated with a pressure increase of 18 +/- 6 mm Hg and a decrease in pH of 0.04 +/- 0.02 units.     

A minority of 46,XX true hermaphrodites are positive for the Y-DNA sequence including SRY

Summary A total of 30 cases of 46,XX true hermaphroditism was analysed for Y-DNA sequences including the recently cloned gene for male testis-determination SRY. In 3 cases, a portion of the Y chromosome including SRY was present and, in 2 cases, was localised, to Xp22 by in situ hybridisation. Since previous studies have shown that the majority of XX males are generated by an X-Y chromosomal interchange, the Xp22 position of the Yp material suggests that certain cases of hermaphroditism can arise by the same meiotic event. The phenotype in the 3 SRY-positive cases may be caused by X-inactivation resulting in somatic mosaicism of testis-determining factor expression giving rise to both testicular and ovarian tissues. Autosomal or X-linked mutation(s) elsewhere in the sex-determining pathway may explain the phenotype observed in the remaining 27 SRY-negative cases.     

Prenatal diagnosis of 21-hydroxylase deficiency congenital adrenal hyperplasia using the polymerase chain reaction

Summary We present an improved method for the prenatal diagnosis of congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency. The polymerase chain reaction (PCR) was used to analyze DNA from an affected index case, the parents, and a cultured chorionic villus sample, for point mutations in the steroid 21-hydroxylase (CYP21) gene. We can predict that the fetus is an unaffected carrier.     

haemolysin of Escherichia coli: Comparison of pore-forming properties between chromosome and plasmid-encoded haemolysins

Abstract Lipid bilayer experiments were performed with chromosome-encoded haemolysin of Escherichia coli . The addition of the toxin to the aqueous phase bathing lipid bilayer membranes of asolectin resulted in the formation of transient ion-permeable channels with two states at small transmembrane voltages. One is prestate (single-channel conductance 40 pS in 0.15 M KCl) of the open state, which had a single-channel conductance of 420 pS in 0.15 M KCl and a mean lifetime of 30 s. Membranes formed of pure lipids were rather inactive targets for this haemolysin. Experiments with different salts suggested that the haemolysin channel was highly cation-selective at neutral pH. The mobility sequence of the cations in the channel was similar if not identical to their mobility sequence in the aqueous phase. The single-channel data were consistent with a wide, water-filled channel with an estimated minimal diameter of about 1 nm. The pore-forming properties of chromosome-encoded haemolysin were compared with those of plasmid-encoded haemolysin. Both toxins share common features, oligomerize probably to form pores in lipid bilayer membranes. Both types of haemolysin channels have similar properties but different lifetimes.     

A portable EAG system for the measurement of pheromone concentrations in the field

A robust and portable apparatus for the measurement of pheromoneconcentrations under field conditions has been developed. Ituses the insect antenna (Lobesia botrana Hb.) itself as a sensitiveand specific pheromone detector. Shock-proof contact with theelectrodes is maintained by fixing the antenna in a specially-shapedplexiglass holder mounted within a glass tube. This allows measurementsto be made while moving the apparatus. Continuous airflow throughthe tube is generated by a suction pump and the incoming aircan be purified by passage through a charcoal filter. This allowsto readjust the offset and to calibrate the instrument by theapplication of pheromone pulses of known concentrations. Removalof the filter allows the direct access of ambient air over theantenna which responds by generating an electro-antennogram(EAG) as a measure of the pheromone concentration. Using the calibration curve, relative pheromone concentrationsin ambient air in a vineyard can be determined. Sample measurementsfrom areas treated with artificial pheromone for pest controlare presented.     

Somatic cell hybrids, sequence-tagged sites, simple repeat polymorphisms, and yeast artificial chromosomes for physical and genetic mapping of proximal 17p.

Somatic cell hybrids retaining the deleted chromosome 17 from 15 unrelated Smith-Magenis syndrome (SMS) [del(17)(p11.2p11.2)] patients were obtained by fusion of patient lymphoblasts with thymidine kinase-deficient rodent cell lines. Seventeen sequence-tagged sites (STSs) were developed from anonymous markers and cloned genes mapping to the short arm of chromosome 17. The STSs were used to determine the deletion status of these loci in these and four previously described human chromosome 17-retaining hybrids. Ten STSs were used to identify 28 yeast artificial chromosomes (YACs) from the St. Louis human genomic YAC library. Four of the 17 STSs identified simple repeat polymorphisms. The order and location of deletion breakpoints were confirmed and refined, and the regional assignment of several probes and cloned genes were determined. The cytogenetic band locations and relative order of six markers on 17p were established by fluorescence in situ hybridization mapping to metaphase chromosomes. The latter data confirmed and supplemented the somatic cell hybrid results. Most of the hybrids derived from [del(17)(p11.2p11.2)] patients demonstrated a similar pattern of deletion for the marker loci and were deleted for D17S446, D17S258, D17S29, D17S71, and D17S445. However, one of them demonstrated a unique pattern of deletion. This patient is deleted for several markers known to recognize a large DNA duplication associated with Charcot-Marie-Tooth (CMT) disease type 1A. These data suggest that the proximal junction of the CMT1A duplication is close to the distal breakpoint in [del(17)(p-11.2p11.2)] patients.