Storage mites sensitivity and allergic respiratory disease

Summary In order to evaluate the frequency of skin sensitivity to Storage Mites and the role of such sensitization in respiratory allergic disease in workers with occupational exposure to stored items we studied 217 dock workers, 93 farmers and 104 white collars.From the results of skin prick tests the sensitization to sole Storage Mites appears significantly higher among people working in docks or farms, compared with a control group. This confirms the role of the working environment in inducing sensitization to Storage Mites. Rhinitis and asthma however affect nearly always (27/29 cases) people with an associated sensitization to House Dust Mites. Further studies are needed to define the allergenic importance of Storage Mites in working environments.     

Analysis of the human regulators of complement activation (RCA) gene cluster with yeast artificial chromosomes (YACs).

The human regulators of complement activation gene cluster (RCA cluster) have been partially characterized with yeast artificial chromosomes (YACs). While the data confirm many points previously elucidated, the finer resolution of YAC mapping has allowed the discovery and/or localization of partial gene duplications, the determination of gene orientations, and the measurement of gaps between known genes. Here nine overlapping YACs that encompass a genomic region of 800 kb, encoding four RCA genes and three gene-like elements, are described. The encoded genes and two of the gene-like elements share the same orientation and are ordered (5' to 3') DAF, CR2, CR1, MCP-like, CR1-like, and MCP. A C4bp-like region lies upstream from DAF and is likely to correspond to one recently observed by F. Pardo-Manuel, J. Rey-Campos, A. Hillarp, B. Dahlback, and S. Rodriguez de Cordoba (1990, Proc. Natl. Acad. Sci. USA 87: 4529-4533). MCP-like, a new genetic element, was discovered and found to be homologous to the 5' portion of the MCP gene. Two large gaps of 85 kb (between CR2 and DAF) and 110 kb (between DAF and the C4bp-like element) could carry additional RCA genes. The arrangement of CR1, MCP-like, CR1-like, and MCP, in that order, strongly suggests that this region was generated by a single duplication of neighboring CR1/CR1-like and MCP/MCP-like forerunners. The RCA YACs will now serve as convenient DNA sources for the subcloning and further characterization of this region.     

Localization of the amphotropic murine leukemia virus receptor gene to the pericentromeric region of human chromosome 8.

The host range of retroviruses is determined primarily by the presence of specific receptors on target cells which are recognized by the retroviral envelope glycoprotein. Somatic cell hybrids have been used to determine the chromosomal locations of several retroviral receptors in mice prior to their molecular cloning. Here we report that by using human-Chinese hamster somatic cell hybrids and a retroviral vector, we have mapped the receptor for the amphotropic murine leukemia virus to the pericentromeric region of human chromosome 8.     

Hydrogen cyanide and embryonal dormancy in apple seeds

Embryos of apple ( Malus domestica Borh. cv. Antonówka) were treated with 1 m M gaseous HCN for 6 h and cultured under a 12 h photoperiod. HCN pretreatment stimulated germination, increased the length of hypocotyls, shortened the main root and decreased the percentages of seedlings with asymmetrically grown as well as with asymmetrically greened cotyledons. High activity of β-cyanoalanine synthase (EC 4.4.1.9) and a sharp increase in cyanogen content during embryo culture suggested very low levels of endogenous HCN. despite the activity of HCN releasing enzymes. The obtained data allow us to postulate an important role for cyanide in the regulatory complex controlling dormancy in apple seeds. Experiments with respiratory inhibitors indicated, however, that HCN pretreatment affected neither the alternative electron transport pathway nor residual respiration.     

Cyanide controls enzymes involved in lipid and sugar catabolism in dormant apple embryos during culture

The activities of alkaline lipase (EC 3.1.1.3, AlkL), isocitrate lyase (EC 4.1.3.1. ICL), pyruvate kinase (EC 2.7.1.40. PK) and glucose–6–phosphate dehydrogenase (EC 1.1.1.49, G6PDH) were determined in cultured, dormant embryos of apple (Malus domestica Borb. cv. Antonówka), pretreated with gaseous HCN. The C₆/C₁ , ratio was estimated in the same material. The activities of AlkL and ICL were not stimulated by HCN pretreatment until the period of maximum stimulation of germination. The activity of G6PDH was inhibited by cyanide only late during the culture of embryos. Therefore, the changes in these activities are considered to be the result and not the cause of enhanced germination. On the other hand, also PK, active very early during the culture of embryos, was modified as a result of the treatment. The cyanide-induced changes in activity of this enzyme in cotyledons (inhibition followed by stimulation) were similar to those in the whole embryo, whereas its changes in the embryonal axis (stimulation followed by inhibition) resembled CN-induced changes in PK in axes of apple seeds submitted to cold stratification (Bogatek and Lewak 1988). The estimation of C₆/C₁ ratios partly confirmed these observations. A role of HCN-induced modifications of PK activity in embryonal dormancy is proposed.     

The life cycle ofAmblyomma parvum Aragao, 1908 (Acari: Ixodidae) under laboratory conditions

A colony ofAmblyomma parvum was started with engorged females collected from cattle in the Province of Salta (25°01 S, 63°56 W), Argentina. The progeny of those ticks were fed on rabbits and the non-parasitic stages maintained at 27±1°C, 83–86% RH in darkness. The life cycle (prefeeding period not evaluated) had a mean duration of 99.6 days. The mean time (days) for the different phases of the cycle were as follows: feeding period of females, 8.0; pre-oviposition period, 5.7; oviposition period, 17.5; minimum incubation period of the eggs, 31.8; feeding period of larvae, 3.2; premoult period to nymphs, 10.9; feeding period of nymphs, 4.7; premoult period to adults, 17.8. The oviposition pattern was typical of an ixodid tick, including a linear relationship between weights of engorged females and the number of eggs laid (r=0.8659). The males increased 18% in weight after feeding on hosts (P<0.01). The mean recovery rates of larvae, nymphs and females were 28.2%, 95.3% and 90.7%, respectively. The nymphs moulting to females were heavier (6.8±0.69 mg) than those moulting to males (3.2±0.29 mg) (P<0.01). A comparison of biological values ofA. parvum with American and non-AmericanAmblyomma species is presented.     

Spring and summer hosts for Pieris rapae in Southern Spain with special attention to Capparis spinosa

The suitability of different host plants for Pieris rapae L. in the South of the Iberian Peninsula, was studied in relation to host plant phenology, female behaviour, and larval development. Capparis spinosa is the only host plant available during the dry season of the year in the area studied. D. virgata, R. raphanistrum, H. incana and S. alba being suitable spring hosts. Comparative studies on mortality, larval development and larval growth between C. spinosa and the spring hosts revealed no significant differences.

---

Résumé L'adéquation de différentes plantes comme hôtes de P. rapae a été examinée en fonction de la phénologie des végétaux, du comportement de la femelle et du développement larvaire dans le sud de la péninsule ibérique. Pendant la saison sèche, C. spinosa est la seule plant convenable dans la zone étudiée. Diplotaxis virgata, Raphanus raphanistrum, Hirschfeldia incana et Sinapis alba sont des hôtes printaniers convenables. La mortalité, le développement et la croissance larvaires ne sont pas différentes sur C. spinosa et sur les hôtes de printemps.

     

Sequential study of the synaptonemal complex in rat (Rattus norvegicus) oocytes by light and electron microscopy

The progression of first meiotic prophase and synaptonemal complex (SC) formation in female rats, Rattus norvegicus S.D., is described through the analysis of the different stages of the first meiotic prophase, and confirms the high synchrony of the process in this species. Leptotene is a stage of very short duration and since pairing of the homologues begins very early, only a leptotene-zygotene stage can be distinguished. The progression of pairing during zygotene is asynchronous. The morphology of the SCs is similar to that described in other species. During diplotene and before desintegration of the lateral elements, desynapsis takes place.In some oocytes a double or even multiple nature of lateral elements was seen. Associations between SCs and nucleoli or nucleolar filaments are frequent. The presence of fragmented SCs can be interpreted as a technical artifact.     

Targets for calcium channel blockers in mammalian skeletal muscle and their respective functions in excitation-contraction coupling

The L-type Ca2+ channel is blocked by 1,4-dihydropyridines (DHP), by phenylalkylamines, by diphenylbutylpiperidines or by benzolactams. We first show with mouse muscle cells in culture that all these L-type Ca2+ channel blockers block contraction. However, voltage-clamp analysis associated to contraction measurements also clearly show that Ca2+ influx through L-type Ca2+ channels is not required for contraction. Therefore, there is a need for a voltage-sensor which would be responsible for the excitation-contraction (E-C) coupling. We are showing here that the voltage-sensor involved in E-C coupling and the L-type Ca2+ channel have a similar pharmacology. Some of the blockers used are more active on the voltage sensor, others on the L-type Ca2+ channel.     

Searching for autolysin functions. Characterization of a pneumococcal mutant deleted in the lytA gene

The first mutant of Streptococcus pneumoniae showing a complete deletion in the lytA gene coding for the N-acetylmuramyl-L-alanine amidase has been isolated and characterized. This amidase was previously the only autolysin detected in this species. This mutant shows a normal growth rate and can be transformed using either chromosomal or plasmid DNA. The most remarkable biological consequences of the absence of the amidase are the formation of small chains (six to eight cells) and the absence of lysis in the stationary phase of growth. In addition, this mutant exhibits a tolerant response against the beta-lactam antibiotics.