Q fever urban cases in Romania

Q fever urban sporadic cases in Romania in the 1981-87 period are reviewed as concerns their incidence, seasonality and epidemiological data. Urban cases represented 76.8% as against 23.2% rural cases from the 134 Q fever sporadic cases detected in this period. Cases were distributed throughout all months with peaks during April (18.4% of cases) and June (19.4%). Infections were not related to contact with livestock or domestic birds or with raw milk drinking. Cases could not be identified as Q fever occupational ones. 36.7% of patients were working in nonalimentary industry and only 12.6% were involved in meat industry, veterinary or human medical practices. New studies concerning unusual sources of urban infection such as dogs, cats or urban street pigeons are emphasized.     

Pleiotropic action of the murine quaking locus: Structure of the qk v allele

The spontaneous allele quaking^viable (qk ^v ) exerts effects on myelination and spermiogenesis. The defects generated by qk ^v were not separated in a multilocus mapping cross that provided a mapping resolution of 0.1 centiMorgans (cM). Furthermore, no distortions suggestive of a large chromosomal anomaly associated with qk ^v were apparent. One plausible interpretation is that the quaking locus contains more than one functional domain, either organized into overlapping genes or expressed by alternative splicing mechanisms. The cloning needed to analyze this locus will be enhanced by the very high resolution of the meiotic mapping cross reported here. The recombinational distances on this qk ^v map were compressed compared with those previously reported in a high-resolution map for qk ^1–1, an embryonic lethal allele of quaking induced by ethylnitrosourea. Additional crosses confirmed prior reports that the sex and the genetic background of the heterozygous parent can affect recombinational distances. These joint effects on recombination are strong enough to account for the discrepancy between the two maps. This variability of two-factor map values leads to the preferred multilocus map-building protocol discussed in the accompanying paper.     

Stability and degradation of mRNA

Differential mRNA stability plays an important role in the regulation of gene expression. Several recent advances have helped to define the general pathways by which mRNA is degraded in prokaryotic cells, although many details remain to be elucidated. Much less is known about the pathways of degradation in eukaryotic cells, but recent studies on specific systems have highlighted both differences from and similarities to prokaryotic pathways.     

An Ecological Imbalance Induced by a Non-Native Species: The Manila Clam in the Venice Lagoon

Among the 19 non-native species of marine invertebrates which have invaded the Venice Lagoon and have established populations, Ruditapes philippinarum, deliberately introduced in 1983, is surely the most successful species. According to the hypothesis that alien species invasion could be favoured by an altered ecological, chemical or physical state of the system induced by anthropogenic disturbance, R. philippinarum turned out to be ‘the right species at the right moment’. By comparing historical data (1968, 1985, 1990) with 1999 data, changes in macrobenthic community, in particular bivalve molluscs, of the lagoon induced by R. philippinarum introduction and subsequent clam exploiting activity were assessed. It has been possible to describe a sharp reduction, both in terms of distribution area and density, of all other filter feeder bivalves. Moreover, by using the clearance rate of the most abundant bivalve species in 1990 and 1999 (Cerastoderma glaucum and R. philippinarum, respectively), it was possible to estimate that the filtration capacity, expressed as l h⁻¹ m⁻², has more than doubled. This has altered the functioning of the ecosystem, resulting in a stronger benthic–pelagic coupling. In this context, R. philippinarum attains control of the system. Considering all this, it is possible to state that the Venice Lagoon ecosystem has entered into a new state, probably more resistant but less resilient, with implications for future management choices.