Ticks (Acari:Ixodidae) of the Blue and White Nile ecosystems in the Sudan with particular reference to theRhipicephalus sanguineus group

Twenty-four adult ixodid tick species, infesting livestock and some wildlife hosts along the Blue and White Nile in the Sudan, were identified. Three species,Boophilus geigyi, Rhipicephalus camicasi andR. bergeoni, were recorded for the first time from the Sudan. Tick numbers on indigenous breeds of cattle (Bos indicus) were relatively low, ranging between 17.1 and 40.5 per animal. Young cattle grazing with the herd carried significantly fewer ticks than older animals. With the exception ofB. annulatus andR. simus, which have extended their distribution further north into Blue Nile, Gezira and Khartoum Provinces, the distribution patterns of the most important cattle ticks have been relatively unchanged over the past 30 years.TheRhicicephalus sanguineus group was represented by six species.R. camicasi was the only species present on cattle, sheep and goats in the north in Kassala and Khartoum Provinces, whereas this species occurred sympatrically withR. guilhoni andR. turanicus further south in Gezira and Blue Nile Provinces. In the Southern Region of the Sudan onlyR. turanicus andR. guilhoni were present, the latter being by far the predominant species, with peak activity towards the end of the rains in the Jonglei Canal Area.R. bergeoni was collected once, from cattle near the Ethiopian border in Blue Nile Province, whereasR. sanguineus sensu stricto was collected throughout the study area, from domestic dogs only. Finally,R. sulcatus was found once on a hare.The distributions of the common tick species are correlated with the occurrence of tick-borne diseases of domestic animals and recommendations for the control of tick-borne diseases and their vectors in the Sudan are given.     

Deletion 2q31.3→2q33.3: gene dosage effect of ribulose 5-phosphate 3-epimerase

In a new case of interstitial del(2q), measurements of ribulose 5-phosphate 3-epimerase activity suggested that the locus for this enzyme might be localized to the subregion 2q32q33.3.     

Dopamine beta-hydroxylase from bovine adrenal medulla contains covalently-bound pyrroloquinoline quinone

Treatment of homogeneous dopamine beta-hydroxylase (DBH) preparations from bovine adrenals with the inhibitor phenylhydrazine (PH) changed the structureless absorption spectrum of DBH into spectra with a maximum at 350 nm. A product with this absorption spectrum could be detached with pronase, enabling its isolation. It appeared to be the C(5) hydrazone of pyrroloquinoline quinone (PQQ) and PH, as judged from its properties and the fact that it could be transformed into PQQ itself. From the yield obtained a ratio of 0.85 PQQ per enzyme subunit was calculated. In contrast to copper-quinoprotein amine oxidases (EC 1.4.3.6), hydrazone formation in DBH did not require saturation of the mixture with O2. DBH is the first copper-quinoprotein hydroxylase found so far. The implications of this finding for the current views on mechanism of action and inhibition by hydrazines are discussed. The success of the recently developed 'hydrazine method' [(1987) FEBS Lett. 221, 299-304] for all different types of amine oxidoreductases, suggest that the method could also be applied to other enzymes for which hydrazines are inhibitors and where the identity of the cofactors has not been established or the presence of PQQ is suspected.     

Hydrazone formation of 2,4-dinitrophenylhydrazine with pyrroloquinoline quinone in porcine kidney diamine oxidase

Homogeneous diamine oxidase (EC 1.4.3.6) from porcine kidney was treated with the inhibitor 2,4-dinitrophenylhydrazine (DNPH). The coloured compounds formed were detached with pronase and purified to homogeneity. When the reaction with DNPH was conducted under an O2 atmosphere, the product (obtained in a yield of 55%) was the C(5)-hydrazone of pyrroloquinoline quinone (PQQ) and DNPH, as revealed by its chromatographic behaviour, absorption spectrum and 1H-NMR spectrum. Only 6% of this hydrazone was formed under air, the main product isolated being an unidentified reaction product of DNPH with the enzyme. Porcine kidney diamine oxidase is the second mammalian enzyme shown to have PQQ as its prosthetic group. In view of the requirements for hydrazone formation with DNPH, it is incorrect to assume that inhibition of this type of enzymes with common hydrazines is simply due to blocking of the carbonyl group of its cofactor.     

Computer-assisted mathematical analysis of sigmoid biological events

A program in BASIC is described which allows accurate quantificationof some numerical parameters that can be objectively correlatedto biological indexes in sigmoid biological events. Attentionwas focused on the polymerization process of actin (a muscleprotein with a mol. wt of 42 000 daltons) studied as the variationin the OD₃₆₀ index with time. The experimental points, if plotted,can be well approximated by a rational function of the typeOD₃₆₀ = f(t), which passes through the origin and can be representedgraphically by a sigmoid curve. The program was very helpfulin comparing the experimental curves and in analysing significantparameters, such as maximum velocity and asymptote, that characterizethese curves and whose interpretation would otherwise be purelysubjective. Received on July 11, 1985; accepted on January 13, 1986     

Rhodotorula nothofagi sp. nov., isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

An unusual Rhodotorula isolated from decayed wood of Nothofagus obliqua (Mirb.) Blume is described and illustrated. This species differs from all accepted Rhodotorula species (1–7, 10) to warrant its establishment as a new species, Rhodotorula nothofagi sp. nov.Postgraduate student from the Instituto de Ecología y de Evolución, Universidad Austral de Chile, Valdivia.     

Increased GH responsiveness to dopamine receptor stimulation in alcohol addicts during the late withdrawal syndrome

In humans the release of growth hormone (GH) elicited by dopamine (DA) and DA agonists may represent a reliable model to assess change in sensitivity of DA receptors. We now report that in chronic alcoholics, 4–7 days after the suspension of alcohol consumption, the increase of GH response to DA infusion was higher than that seen in non alcoholic volunteers. The specificity of this GH response to DA administration was demonstrated by the use of domperidone, a novel peripheral antagonist of DA receptors. These results suggest the development of hyper-responsiveness of DA receptors involved in the control of GH secretion in chronic alcoholics during the later phases of the “withdrawal syndrome”.     

Paleolirnnological records of carotenoids and carbonaceous particles in sediments of some lakes in Southern Alps

Stratigraphic analyses of organic carbon, organic nitrogen and algal and bacterial carotenoids in short cores of profundal sediments of four alpine lakes (Tovel, Leit, Paione superiore and Tom) were used to reconstruct their trophic history. In addition, depth distribution of carbonaceous particle concentrations provided information on lake contamination from atmospheric deposition. In three lakes (Tovel, Leit and Tom), sedimentary carotenoids unique to sulfur photosynthetic bacteria (okenone and isorenieratene) provide evidence of changes in the oxygen, light and sulfide conditions in the water column. All the lakes are oligotrophic or moderately productive, and the algal community is dominated by Chlorophyta, Pyrrhophyta and Cryptophyta. Cyanobacteria are rather poorly represented. The steep increase of carbonaceous particles in the uppermost sediment layers of all the lakes suggests that lake contamination by atmospheric transport of pollutants began in the 1940s to 1950s. These data, coupled with those from a parallel study on Chrysophycean scale-inferred pH, indicate recent acidification in those which are poorly buffered (Paione superiore and Leit).