A 25-year record of polycyclic aromatic hydrocarbons in soils amended with sewage sludges

We studied polycyclic aromatic hydrocarbons (PAHs) in crop soils amended with 1000 tonnes dry weight of sewage sludges per 10,000 m² from 1974 to 1992, then after sludges addition from 1993 to 1999. The absence of variations of total PAHs levels of control soils, averaging at 123 μg/Kg, shows the absence of horizontal contamination. During sludges addition, the total PAHs levels in amended soils increased from 232 to 402 μg/Kg. Seven years after sludges addition, it decreased to 275 μg/Kg, which is still more than twice –the levels of control soils. This finding shows that sludges PAHs are preserved in crop soils for long periods of time, on a human scale.     

Food ingestion and growth of the diatom-feeding nematode Chromadorita tenuis

Feeding rates and growth of the free-living brackish water nematode Chromadorita tenuis (G. Schneider, 1906) was studied throughout its life cycle. Populations were fed with the pennate diatom Nitzschia palea var debilis (Kütz.) Grunow in the laboratory at 18°C in agar plates based on seawater of 6 S. On the average, during the first day after hatching they ingest 1 g of cell contents, equal to 20 times the body weight, and the body weight increased from 3.6 to 6.9 ng C. During the entire 12.5 d of juvenile life the weight increased 40 times, whereas the weight only doubled during adult life, which is almost entirely devoted to reproduction. Adult virgins are larger than mated females. The large size of adult virgins indicates that about 50% of the gonad energy might be transferred to somatic growth. The size-frequency distribution of adult body lengths of a laboratory grown population as compared to four wild populations shows that the food offered to the laboratory population was of a poor quality.     

Histochemical demonstration of mercury in the intestine,nephridia and epidermis of the marine polychaete Nereis virens exposed to inorganic mercury

Marine polychaetes Nereis virens (Sars) were exposed to 9 ppb Hg as mercuric chloride in the aquarium water. Concentrations of mercury in the water and in the worms were monitored using radiolabelled mercury. After 11 d, the average mercury concentration in the nereids was 8.41 ppm Hg and the bioconcentration factor was calculated to be 930. Accumulations of mercury in the tissues were made visible for light and electron microscopy by autometallographic silver enhancement. Mercury was demonstrated in the intestine, nephridia, epidermis and cuticula. In the intestine, mercury was found to be located predominantly in the apical part of the epithelial cells. In the nephridia, mercury deposits were apparent in the peritoneal cells of the nephridial tubules. Silver-enhanced mercury was also observed at the epicuticula, in the collagen fibres of the endocuticula and in the epidermal basal cells. Intracellularly, the observed mercury accumulations were localised predominantly in lysosomes. Extracellularly, mercury was observed in the basal laminae of the intestine and the epidermis, and also in the intestinal peritrophic membrane. How N. virens copes with mercury toxicity is discussed.     

Morphology of grooming limbs in species of Petrolisthes and Pachycheles (Crustacea: Decapoda: Anomura: Porcellanidae): a scanning electron microscopy study

The morphology of the grooming limbs, the 5th pair of pereiopods, was studied by scanning electron microscopy in six species of porcellanid crabs, Petrolisthes cabrilloi, P. cinctipes, P. armatus, P. galathinus, Pachycheles monilifer, and Pachycheles rudis, and their function was inferred by comparison with findings from previous studies. Grooming limb morphology was almost identical among the four Petrolisthes species and differed little compared to that of the two Pachycheles species. The 5th pereiopods bore a basal tuft of mechanoreceptive setae, three different types of grooming setae armed with setules or denticles, two types of smooth sensilla for location and identification of fouling objects, and a terminal, toothed chela for picking firmly attached objects off the gills and body. The grooming limb was extremely flexible and could reach most parts of the body, including the gill chamber on the opposite side. The grooming limb morphology in Petrolisthes cabrilloi is consistent with its wellknown effectiveness in preventing parasitism by the rhizocephalan Lernaeodiscus porcellanae. Grooming setae remove recently attached cyprids, while the chela can grip and remove the much smaller, firmly attached kentrogons. Porcellanid crabs not known to host rhizocephalans, however, had grooming limbs almost identical to those of Petrolisthes cabrilloi despite their previously demonstrated failure to prevent settlement and infestation by L. porcellanae larvae. The effectiveness of P. cabrilloi in removing kentrogons, therefore, seems also to depend on behavioral adaptations whereby this species recognizes the parasite larvae as high-threat objects.     

High recovery of culturable bacteria from the surfaces of marine algae

The culturability of heterotrophic marine bacteria obtained from the surfaces of two species of marine algae (Lobophora variegata andHalimeda copiosa) was assessed by comparing total DAPI-stained cell counts to colony-forming bacterial counts on two agar media. The colony-forming bacterial counts on a low-nutrient medium (LN) consisting of seawater and agar were significantly greater for both algal species than counts obtained on a high-nutrient medium (HN) similar in composition to that typically used for the isolation of heterotrophic marine bacteria. On average, 14 and 58%, respectively, of the total bacteria fromL. variegata andH. copiosa were culturable on LN. These recovery rates far exceed those typically reported for marine bacteria. Of 119 LN strains obtained in pure culture, 55% failed to grow on HN. The yeast extract component of HN (1.5 gl^-1) was responsible for the majority of the observed inhibition, suggesting that this nutrient can be highly toxic to marine bacteria. Eighty-nine percent of the strains inhibited by HN were capable of growth when the nutrients in this medium were diluted by a factor of 100 with seawater. Of 66 epiphytic strains, 30 (45%) initially inhibited by HN showed the ability to adapt to this medium after a period of laboratory handling. The initial inability of low-nutrient-adapted bacteria to grow on high-nutrient media may be due to nutrient shock. The results presented here indicate that the culturability of specific populations of marine bacteria can be dramatically improved by the use of low-nutrient media. Further, the importance of developing new medium formulations that eliminate traditional nutrients, some of which are clearly toxic to bacteria, is demonstrated.     

45,X karyotype: May the diagnosis be suspected on ultrasonic examination in the second trimester of pregnancy?

We report three cases of Turner's syndrome with cystic hygromata, which were diagnosed by routine ultrasound scanning before amniocentesis in the second trimester of pregnancy. Maternal and amniotic level of alpha-fetoprotein were normal. Karyotyping carried out afterwards showed a 45,X karyotype. Our data indicate, that cystic hygromata in Turner's syndrome may coexist with a normal amniotic fluid AFP, thus questioning the theory of leakage from the hygroma. It remains to be investigated if all cases of Turner's syndrome present a cystic hygroma in utero.     

An Optimised Direct Lysis Method for Viral RNA Extraction and Detection of Foodborne Viruses on Fruits and Vegetables

Detection of norovirus (NoV) and hepatitis A virus (HAV) on fruits and vegetables using current standard methodologies can be inefficient. Method optimisat