NMR solution structure of a dsRNA binding domain from Drosophila staufen protein reveals homology to the N-terminal domain of ribosomal protein S5.

The double-stranded RNA binding domain (dsRBD) is an approximately 65 amino acid motif that is found in a variety of proteins that interact with double-stranded (ds) RNA, such as Escherichia coli RNase III and the dsRNA-dependent kinase, PKR. Drosophila staufen protein contains five copies of this motif, and the third of these binds dsRNA in vitro. Using multinuclear/multidimensional NMR methods, we have determined that staufen dsRBD3 forms a compact protein domain with an alpha-beta-beta-beta-alpha structure in which the two alpha-helices lie on one face of a three-stranded anti-parallel beta-sheet. This structure is very similar to that of the N-terminal domain of a prokaryotic ribosomal protein S5. Furthermore, the consensus derived from all known S5p family sequences shares several conserved residues with the dsRBD consensus sequence, indicating that the two domains share a common evolutionary origin. Using in vitro mutagenesis, we have identified several surface residues which are important for the RNA binding of the dsRBD, and these all lie on the same side of the domain. Two residues that are essential for RNA binding, F32 and K50, are also conserved in the S5 protein family, suggesting that the two domains interact with RNA in a similar way.     

Mapping murine loci for seizure response to kainic acid

Mature DBA/2J (D2) mice are very sensitive to seizures induced by various chemical and physical stimuli, whereas C57BL/6J (B6) mice are relatively seizure resistant. We have conducted a genome-wide search for quantitative trait loci (QTLs) influencing the differential sensitivity of these strains to kainic acid (KA)-induced seizures by studying an F₂ intercross population. Parental, F₁, and F₂ mice (8–10 weeks of age) were injected subcutaneously with 25 mg/kg of KA and observed for 3 h. Latencies to focal and generalized seizures and status epilepticus were recorded and used to calculate an overall seizure score. Results of seizure testing indicated that the difference in susceptibility to KA-induced seizures between D2 and B6 mice is a polygenic phenomenon with at least 65% of the variance due to genetic factors. First-pass genome screening (10-cM marker intervals) in F₂ progeny (n = 257) documented a QTL of moderate effect on Chromosome (Chr) 1 with a peak LOD score of 5.5 (17% of genetic variance explained) localized between D1Mit30 and D1Mit16. Provisional QTLs of small effect were detected on Chr 11 (D11Mit224–D11Mit14), 15 (D15Mit6–D15Mit46) and 18 (D18Mit9–D18Mit144). Multiple locus models generally confirmed the Mapmaker/QTL results and also provided evidence for another QTL on Chr 4 (D4Mit9). Multilocus analysis of seizure severity suggested that additional loci on Chrs 5 (D5Mit11), 7 (D7Mit66), and 15 (D15Nds2) might also contribute to KA-induced seizure response. Overall, our results document a complex genetic determinism for KA-induced seizures in these mouse strains with contributions from as many as eight QTLs. Received: 16 April 1996 / Accepted: 21 October 1996     

Cloned DNA probes distinguish endemic and exotic Entomophaga grylli fungal pathotype infections in grasshopper life stages

Entomophaga grylli is a fungal pathogen of grasshoppers and at least three pathotypes are recognized world-wide. Pathotypes 1 and 2 are endemic to North America while the Australian pathotype 3 had been released into two field sites in North Dakota between 1989 and 1991. Grasshoppers were collected over the summer at the field sites in 1992 and assessed for pathotype infection by cloned DNA probe analysis. The three most predominant grasshopper species that were infected ( Melanoplus sanguinipes, M. bivittatus and Camnula pellucida ) were assessed for pathotype infection with respect to their life stages (nymphal instars and adult males and females). Pathotype 1 predominantly infected grasshoppers in the subfamilies Oedipodinae and Gomphocerinae and pathotype 2 predominantly infected grasshoppers in the subfamily Melanoplinae. Early-instar M. sanguinipes and M. bivittatus had higher pathotype 2 infection frequencies, while late-instar and adult C. pellucida had higher pathotype 1 infection frequencies. Cross-infection by the pathotypes did occur in up to 3% of the individuals, on a per species basis, and primarily in later instar and adult grasshoppers. Pathotype 3 infections occurred in later instar and adults of the three grasshopper species. Infection of grasshoppers by E. grylli pathotypes is discussed with reference to the fungal life cycles.     

Ventilation and metabolism among rat strains

Strohl, Kingman P., Agnes J. Thomas, Pamela St. Jean, EvelynH. Schlenker, Richard J. Koletsky, and Nicholas J. Schork. Ventilation and metabolism among rat strains. J. Appl. Physiol. 82(1): 317-323, 1997.We examinedventilation and metabolism in four rat strains with variation in traitsfor body weight and/or blood pressure regulation.Sprague-Dawley [SD; 8 males (M), 8 females (F)], BrownNorway (BN; 10 M, 11 F), and Zucker (Z; 11 M, 12 F) rats were comparedwith Koletsky (K; 11 M, 11 F) rats. With the use of noninvasiveplethysmography, frequency, tidal volume, minute ventilation(E),O₂ consumption, andCO₂ production were derived atrest during normoxia (room air) and during the 5th minute of exposureto each of the following: hyperoxia (100% O₂), hypoxia (10%O₂-balanceN₂), and hypercapnia (7%CO₂-balance O₂). Statistical methods probedfor strain and sex effects, with covariant analysis by body weight,length, and body mass. During resting breathing, strain effects werefound with respect to both frequency (BN, Z > K, SD) and tidal volume(SD > BN, Z) but not to E. Sexinfluenced frequency (F > M) alone. Z rats had higher values forO₂ consumption,CO₂ production, and respiratoryquotient than the other three strains, with no independent effect bysex. During hyperoxia, frequency was greater in BN and Z than in SD orK rats; SD rats had a larger tidal volume than BN or Z rats; Z rats hada greater E than K rats; and M had alarger tidal volume than F. Strain differences persisted duringhypercapnia, with Z rats exhibiting the highest frequency andE values. During hypoxic exposure,strain effects were found to influenceE (SD > K, Z), frequency (BN > K), and tidal volume (SD > BN, K, Z). Body mass was only amodest predictor of E during normoxia, of both E and tidal volume withhypoxia, hypercapnia, or hyperoxia, and of frequency duringhypercapnia. We conclude that strain of rats, more than their body massor sex, has major and different influences on metabolism, the patternand level of ventilation during air breathing, and ventilation duringacute exposure to hypercapnia or hypoxia.

     

Muscle-specific enzyme activity patterns of the capillary bed of human oro-facial,masticatory and limb muscles

Enzyme-histochemical methods were used to analyse the activities of alkaline phosphatase (AP), dipeptidylpeptidase IV (DPP IV) and adenosine triphosphatase (ATPase) in capillaries of four different human oro-facial muscles, the major and minor zygomatic, the orbicularis oris and buccinator, one masticatory, the masseter and two limb muscles, the biceps brachii and first dorsal interosseus muscles. In all muscles, except for the orbicularis oris, the majority of the capillaries lacked enzyme activity. Therefore, none of these enzymes seems to be reliable as a general marker for human muscle capillaries. In general, the capillaries of the limb muscles and the major and minor zygomatic and the buccinator, were similar in their staining pattern for AP and ATPase, but differed in DPP IV staining. The orbicularis oris muscle differed from the other muscles by showing the largest proportion of capillaries with AP and ATPase activity. The masseter muscle had the largest proportion of capillaries stained for DPP IV. The muscle specific differences in enzyme activity of the capillaries are in agreement with our previous findings of specific differences between limb, oro-facial and masticatory muscles with respect to capillary supply and composition of fibre types and myosins. The results reflect functional specialization of the capillary bed of human muscles.     

Isolation of arboviruses from insects collected at Beatrice Hill, Northern Territory of Australia, 1974-1976

Between October 1974 and May 1976, 57 596 mosquitoes, 169 957 Culicoides, 5923 Lasiohelea and 1043 phlebotomines were collected for virus isolation at Beatrice Hill (lat. 12 degrees 39'S.,long. 131 degrees 20'E.) in the Northern Territory of Australia. A total of 94 viruses belonging to 22 different serological groupings was isolated. The following species of insect yielded viruses which were identified and those viruses marked with an asterisk represent a new record of insect host: Culex annulirostris: Ross River, Kokobera, Barmah Forest, Corriparta, Eubenangee*, Wongorr; Anopheles amictus: Mapputta*; An bancroftii: bovine ephemeral fever*; An farauti: Eubenangee*; An annulipes: Mapputta; Culicoides marksi: Barmah Forest*, Belmont, Eubenangee*, Wallal, Warrego, Leanyer*, Parker's Farm*, Humpty Doo*; C. peregrinus: Beatrice Hill*; C. oxystoma: Bunyip Creek*, Marrakai*; C. pallidothorax: Wongorr*; C. histrio: Thimiri*; Lasiohelea spp.: Humpty Doo*. Pools of mixed species of Culicoides yielded bluetongue, Belmont, CSIRO Village, Warrego and Facey's Paddock viruses. Filter-passing agents not yet identified, were isolated from Cx annulirostris and An bancroftii. As well as providing new locality records for all but one of the 22 viruses isolated, the study yielded five new viruses (bluetongue serotype 20, CSIRO Village, Marrakai, Beatrice Hill and Humpty Doo viruses) and a new record for Thimiri virus which had not been recorded previously in Australia nor had it been isolated from an arthropod. Nine of the viruses isolated occur in more than one family of Diptera.     

Decreased lipolysis in peanuts by a pyridazinone bioregulator

Peanut,Arachis hypogaea, plants were treated in the field with the bioregulator BAS 105 00W, 4-chloro-5-dimethylamino-2-phenylpyridazin-3-one, a substituted pyridazinone, at different times of development. The seeds were harvested, dried, hand-shelled, and analyzed for lipoxygenase activity and conjugated diene hydroperoxide content. Reduced lipoxygenase activity occurred when the bioregulator was applied to the plants at flowering and pegging. The conjugated diene hydroperoxide content decreased the most in peanuts when the bioregulator was applied at pegging. The apparent K_m for lipoxygenase of treated peanuts with linoleic acid as substrate was the same as that for untreated peanuts.     

Assay of interferon and viral antibodies in the cerebrospinal fluid in clinical neurology and psychiatry

Cerebrospinal fluids (CSF) of 245 neurological and 194 psychiatric patients were tested for viral antibodies and interferon. Complement dependent neutralizing antibodies to Herpesvirus hominis 1 were found in the CSF of patients with encephalitis (50.6%), meningitis (35.4%), lesions of peripheral nerves (36.9%), sclerosis multiplex (41.2%), schizophrenia (31.9%), senile dementia (51.4%), mental retardation (11.1%), ethylism (43.5%). Neutralizing antibodies to tick-borne encephalitis virus were found in the CSF of 38% patients with encephalitis, in 14% meningitis, 11% lesions of peripheral nerves and also in 5.6--11.8% of psychiatric patients. In encephalitis, meningitis and in lesions of peripheral nerves were found in the CSF frequently plaque neutralizing antobidies to the tick-borne orbivirus Lipovník, complement-fixing antibodies to lymphocytic choriomeningitis virus and hemagglutination inhibiting antibodies to measles virus. In multiple sclerosis were detected CSF antibodies to measles virus (44%), Herpesvirus hominis 1 (41.2%) and Lipovník virus (52.6%). In neurological patients were observed CSF antibodies simultaneously to two or three viruses in 16.7 to 40.6%, while in psychiatric patients in zero to 4.6%. CSF interferon was found in psychiatric patients with an equal or even higher incidence (33.7 to 57.1%) than in the neurological patients (29.6--38.6%, in multiple sclerosis only 16.7%). Non-interferon virus inhibitors were excluded. The evaluation of the ratio of serum and CSF titers of viral antibodies and of interferon indicated local synthesis of both in the central nervous system -- with the exception of antibodies to Herpesvirus hominis 1 in CSF of some patients with very high titres in serum and probable lesions of the blood brain barrier.     

Carotenogenesis and asparagine inLeptosphaeria michotii (West) Sacc.

Summary InLeptosphaeria michotii U¹⁴C-asparagine was incorporated into the coloured carotenoids, the synthesis of which carried on till day 8. The pigment turnover, obvious from day 6, was not modified by the light conditions used.Nicotine (0.25 to 4.5 mM) has been used to study carotenogenesis and sporulation rhythm regulation inL. michotii fed with asparagine 2.6 mM. Control cultures contained in darkness -carotene only and in continuous light -carotene 98% and lycopene 2%. The mold receiving nicotine 0.25 mM in darkness contained -carotene 98% and lycopene 2%. For nicotine 0.5 mM and upwards -carotene decreased, lycopene increased and -carotene appeared, the balance between these pigments also depending on the light conditions. Whereas period length () of the sporulation rhythm increased from one cycle to the next in control cultures in darkness, it was stabilized either by continuous light ( 27 h) or by nicotine 0.25 mM ( 30 h). For nicotine 0.5 mM sporulation was uniform in darkness or in light.