Degradation of atrazine and isoproturon in the unsaturated zone: a study from Southern England

The potential for degradation of atrazine or isoproturon in the unsaturated zone of two boreholes was studied under laboratory conditions. Intact and uncontaminated samples were obtained from regular depths of 0–16.45 m and 0–9 m using a percussion coring technique. The results showed that the deep unsaturated zone contained micro-organisms capable of degrading atrazine or isoproturon. The rate of degradation was much faster in surface soil than in most unsaturated materials of both boreholes. The amount of atrazine remaining six months after incubation also varied between the two boreholes. A relatively small amount of atrazine was lost from sterilised samples, suggesting a significant role for microbial degradation. The addition of nutrient and energy sources into materials of low degradation capacity did not enhance the degradation of atrazine. Degradation rate was more related to the presence of a competent microbial population rather than to the presence of indigenous organic matter. However, the competent micro-organisms are more likely to be present when the organic matter content is high. The type and activity of these micro-organisms and their physical environment may have considerable influence on atrazine degradation and are likely to be responsible for much of the variation in the rate of degradation observed at different depths. © 1999 Society of Chemical Industry     

Potential Dissipation of Atrazine in the Soil Unsaturated Zone: a Comparative Study in Four European Countries

A European-wide project has been undertaken to establish the potential for dissipation of atrazine in the soil subsurface environment. Samples were obtained, avoiding contamination, in four countries (Belgium, Greece, Hungary and UK) and laboratory studies carried out. In order to make comparisons between results from each laboratory, a ring experiment was carried out using common methodology for sampling, extraction and analytical techniques. Subsurface materials from each country were distributed to the other countries. Atrazine dissipation was determined in each country for all materials under the same laboratory conditions. The results of this comparative study showed generally good agreement between all laboratories. Significant potential microbiological dissipation was detected in certain samples. Where differences occurred between laboratories this was attributed to small, spatially heterogeneous microbial populations in the subsurface materials. © 1997 SCI.     

Comparison of three pea cultivars (Pisum sativum) regarding their responses to direct and bicarbonate-induced iron deficiency

The aim of this work was to explore leaf characteristics underlining the difference in the sensitivity of pea cultivars (cv. Kelvedon, Douce and Lincoln) to Fe deficiency. Plants were grown in a greenhouse under controlled conditions in continuously aerated solution. Three treatments were used: 30 μM Fe (+Fe), 0 μM Fe (−Fe); direct deficiency and 30 μM Fe + 10 mM NaHCO₃ (+Fe+Bic); indirect deficiency for 12 days. Growth parameters, iron status, potassium content, chlorophyll fluorescence and photosynthetic capacity were studied. Our results showed that Fe deficiency led to a significant decrease of chlorophyll index (SPAD readings) and bivalent iron content in all Pisum sativum cultivars. The lower reduction was observed in Fe-deficient plants of Kelvedon and Douce. In addition, shoot length and whole plant dry weight were not affected by Fe deficiency in the latter cultivars. Both tolerant cultivars showed higher accumulation of potassium content in their leaves compared with the sensitive one. Moreover, both chlorophyll fluorescence ratios (F_v/F_m and F_v/F₀) were significantly decreased in all cultivars under both Fe deficiency treatments. The photosynthetic electron transport activity was reduced in the sensitive cultivar, especially in the absence of iron. The adverse effect of bicarbonate-induced Fe deficiency on the above mentioned parameters were more pronounced than that of the direct one. The capacity of both tolerant cultivars to preserve adequate chlorophyll synthesis, photosynthetic capacity and plant growth under iron-limiting conditions is related to the suitable nutrition of their leaves in ferrous iron, due to (at least partially) their higher potassium content.     

Aphid transmissibility of different European beet polerovirus isolates

Different field isolates of the ‘beet poleroviruses’ Beet mild yellowing virus (BMYV) and Beet chlorosis virus (BChV) (genus Polerovirus, family Luteoviridae) collected in France and Poland were evaluated for transmissibility from and to sugar beet plants by different aphid species. In general, both BMYV and BChV were efficiently transmitted by Myzus persicae and by a French clone of Macrosiphum euphorbiae. In contrast, transmissibility of the two poleroviruses by an English clone of M. euphorbiae was evidently weaker, although the aphid samples contained the virus as demonstrated by RT-PCR. None of the BMYV or BChV isolates was transmitted by Aphis fabae or Myzus ascalonicus. In attempting to correlate biological properties with molecular variations, the RT proteins were sequenced. Some amino acid point variations, presumably affecting aphid transmissibility, were identified.     

Salmonella Prevalence and Distribution of Serotypes in Apparently Healthy Slaughtered Camels (Camelus dromedarius) in Eastern Ethiopia

The present study was undertaken to determine the prevalence and distribution of Salmonella from apparently healthy slaughtered camels in Eastern Ethiopia. A total of 714 samples (faeces, mesenteric, lymph nodes, spleen, liver, abdominal and diaphragmatic muscles) from 119 slaughtered camels were analysed. Salmonellae were detected from 116 (16.2%) of the 714 samples examined. Eighteen (15.1%) faeces, 19 (15.9%) mesenteric lymph nodes, 14 (11.8%) livers and 17 (14.3%) spleen samples (n = 119 for each) were positive for Salmonella. Salmonellae were found in 20.1% of the abdominal and diaphragmatic muscles. A total of sixteen different serotypes were identified of which Salmonella saintpaul (38.8%) and S. braenderup (22.4%) were the most prevalent followed by S. muenchen (8.6%), S. kottbus (6.0%) and S. havana (5.2%). Other serotypes, including S. typhimurium, S. heidelberg and S. enteritidis were also detected from Ethiopian camels.     

Molecular identification of chlamydial cause of abortion in small ruminants in Jordan

Chlamydophila abortus (Ch. abortus) is the etiological agent of ovine enzootic abortion (OEA) and one of the most common infectious agents of abortion in small ruminants worldwide. RFLP-PCR analysis of the outer membrane protein gene (OMP2 gene) was used for diagnosis and characterization of chlamydial causes of abortion in small ruminants in Jordan. Sixty-six placental tissues and 15 vaginal swabs were collected from aborted ewes and does to identify cause of abortion in Jordan. Thirty-eight placental samples (58 %) and 13 vaginal swabs (87 %) were positive for chlamydial DNA. Shedding of bacteria in vaginal swabs was detected within 7 days after abortion. The results of this study showed that chlamydiosis is one of the important causes of abortion in small ruminants in Jordan. In addition, vaginal swab is an excellent sample for molecular diagnosis of chlamydiosis. DNA sequencing and RFLP analysis of the OMP2 reveal that all chlamydial cause of abortion in small ruminants in Jordan are due to Ch. abortus. While, Ch. pecorum was not detected in any sample. OMP2 gene of the isolated Jordanian strain was identical (100 %) to Ch. abortus FAS strain. In conclusion, Ch. abortus is an important cause of abortion in Jordan; vaginal swab within 7 days of abortion can be used for molecular diagnosis of chlamydiosis in small ruminants.     

Physiological and morphological response of tomato plants to nano-chitosan used against bio-stress induced by root-knot nematode (Meloidogyne incognita) and Tobacco mosaic tobamovirus (TMV)

European Journal of Plant Pathology - Root-knot nematodes (Meloidogyne spp.) have been reported to be responsible for large economic losses of agricultural crops due to their wide host range and...     

Experimental model of Border Disease Virus infection in lambs: comparative pathogenicity of pestiviruses isolated in France and Tunisia

Pestiviruses have been isolated from live sheep pox Tunisian vaccines. Vaccination with these vaccines caused outbreaks of Border Disease in Tunisia. In order to study more precisely the pathogenicity of these isolates, three groups of eight four month old lambs from a pestivirus-free flock were infected by the intratracheal route with a French strain (AV) and two Tunisian isolates (SN3G and Lot21). Clinical, hematological, immunological and virological parameters were evaluated. The three groups developed mild fever and leucopaenia by day 3 to 6 post infection (pi). The differences in the weight curves were not significant. Viruses were isolated from the peripheral blood buffy coat cells by day 4 to 9 pi. Antibodies were present on day 16 pi following infection by the French strain and on day 21 pi with the Tunisian isolates. The results demonstrated that SN3G and Lot21 are almost similar to the French strain used as the reference strain. In field conditions, they could induce economical losses in naive flocks, alone or in association with other pathogens.