ASSESSMENT OF IMPEDANCE MICROBIOLOGICAL METHOD FOR THE DETECTION OF ESCHERICHIA COLI IN FOODS

This study was conducted to determine the sensitivity and specificity of the impedance-based microbiological method for the detection of Escherichia coli in foods within 24 h of testing. A Malthus Microbiological Analyzer system (Malthus System V, Malthus Instruments Ltd., Bury, United Kingdom), and a modified Malthus Coliform Broth Medium (MCBM), and an incubation temperature of 44C were used. The sensitivity of the impedance method was determined by testing E. coli-negative food samples spiked with different concentrations of E. coli. The specificity of the method was determined by testing E. coli -negative food samples spiked with Klebsiella pneumoniae, Enterobacter cloacae and Pseudomonas aeruginosa. The test results were compared with those obtained by the Most Probable Number (MPN) method. Milk, milk products, raw and ready-to-eat meats, and vegetables were tested for the presence of E. coli by both methods. The sensitivity of the impedance method and the MPN method for the detection of foods containing 10¹ CFU/g was 100% and 84.4%, respectively. Both methods had a specificity of 100% for food samples spiked with 10¹ CFU/g E. coli. The specificity of the impedance and the MPN methods for the detection of E. coli in naturally contaminated milk and meat samples was 100% and 95.7% respectively. E. coli was detected in foods by the impedance method within 4–24 h of testing at a detection limit of 1 CFU/mL. These results demonstrate that the impedance method can be used as a rapid and sensitive method for the detection of E. coli in foods.     

Evolution of Paleocene to Early Eocene larger benthic foraminifer assemblages of the Indus Basin,Pakistan

Afzal, J., Williams, M., Leng, M.J., Aldridge, R.J. & Stephenson, M.H. 2011: Evolution of Paleocene to Early Eocene larger benthic foraminifer assemblages of the Indus Basin, Pakistan. Lethaia, Vol. 44, pp. 299–320. The Paleocene–Early Eocene carbonate successions of the Indus Basin in Pakistan formed on the northwestern continental shelf margin of the Indian Plate in the eastern Tethys Ocean. Based on larger benthic foraminifera (LBF), eight Tethyan foraminiferal biozones (SBZ1–SBZ8) spanning the Paleocene to Early Eocene interval are identified. The base of the Eocene is identified by the first appearance of Alveolina sp. Other stratigraphically important LBFs that are characteristic of the earliest Eocene are Ranikothalia nuttalli, Discocyclina dispansa and Assilina dandotica. Stable isotope analysis through the Paleocene–Eocene (P–E) boundary interval identifies more positive δ¹³C values for the Late Paleocene (+3.4‰ to +3.0‰) and lower values (+2.7‰ to +1.6‰) for the earliest Eocene. However, there is insufficient sampling resolution to identify the maximum negative δ¹³C excursion of the Paleocene–Eocene Thermal Maximum. During Late Paleocene times LBF assemblages in the Indus Basin were taxonomically close to those of west Tethys, facilitating biostratigraphic correlation. However, this faunal continuity is lost at the P–E boundary and the earliest Eocene succession lacks typical west Tethys Nummulites, while Alveolina are rare; LBFs such as Miscellanea and Ranikothalia continue to dominate in the Indus Basin. The absence of Nummulites from the earliest Eocene of Pakistan and rarity of Alveolina, elsewhere used as the prime marker for the base of the Eocene, may imply biogeographical barriers between east and west Tethys, perhaps caused by the initial stages of India‐Asia collision. Later, at the level of the Eocene SBZ8 Biozone, faunal links were re‐established and many foraminifera with west Tethys affinities appeared in east Tethys, suggesting the barriers to migration ceased. □Biostratigraphy, Eocene, India‐Asia collision, larger benthic foraminifera, palaeoecology, Paleocene.     

Ontogenesis, Differentiation and Precocious Germination in Anther-derived Somatic Embryos of Grapevine (Vitis vinifera L.): Embryonic Organogenesis

Somatic embryos ofVitis vinifera L. ‘Grenache noir’develop abnormally and form viable plantlets at very low frequencies.They grow continuously and, after the torpedo stage, they formgiant structures which do not undergo further organogenesis.Morphological, histological and cytochemical data were usedto study development from the globular to the giant-embryo stage.Histological organization of somatic embryos until the torpedostage was similar to that of zygotic embryos. Somatic embryosformed bipolar axes, which differentiated precociously and simultaneouslya root and a shoot meristem. However, they differed from theirzygotic homologues by forming a cotyledonary crown or multiplecotyledons and by their rapid cellular differentiation. At theend of the torpedo stage and up to the giant-embryo stage, somaticembryos underwent some characteristic events of germination:the radical grew, tannins accumulated, and protodermal cellssuberized. However the shoot apex was rapidly disorganized anddisappeared. This peculiar behaviour is discussed in comparisonwith the phenomenon of precocious germination often observedfor immature zygotic embryos inin vitro culture. Vitis vinifera ; grapevine; somatic embryo development; precocious germination; histology     

A diminution in ascorbate oxidase activity affects carbon allocation and improves yield in tomato under water deficit

The regulation of carbon allocation between photosynthetic source leaves and sink tissues in response to stress is an important factor controlling plant yield. Ascorbate oxidase is an apoplastic enzyme, which controls the redox state of the apoplastic ascorbate pool. RNA interference was used to decrease ascorbate oxidase activity in tomato (Solanum lycopersicum L.). Fruit yield was increased in these lines under three conditions where assimilate became limiting for wild‐type plants: when fruit trusses were left unpruned, when leaves were removed or when water supply was limited. Several alterations in the transgenic lines could contribute to the improved yield and favour transport of assimilate from leaves to fruits in the ascorbate oxidase lines. Ascorbate oxidase plants showed increases in stomatal conductance and leaf and fruit sugar content, as well as an altered apoplastic hexose : sucrose ratio. Modifications in gene expression, enzyme activity and the fruit metabolome were coherent with the notion of the ascorbate oxidase RNAi lines showing altered sink strength. Ascorbate oxidase may therefore be a target for strategies aimed at improving water productivity in crop species.     

Ontogenesis, Differentiation and Precocious Germination in Anther-derived Somatic Embryos of Grapevine (Vitis vinifera L.): Proembryogenesis

Histological steps of callogenesis and proembryogenesis in anthercultures ofVitis vinifera L. ‘Grenache noir’ aredescribed. Embryogenic calli were obtained on Nitsch and Nitschmedium supplemented with 1mgl^-12,4-dichlorophenoxyacetic acid(2,4-D) and 0.25mgl^-1benzylaminopurine (BAP). Calli were initiatedfrom anther connective cells only and no division of microsporesoccurred. The embryos were hence of somatic origin. Proembryosdeveloped either directly (i.e. without intervening callus)from the endothecium, or indirectly from the connective-derivedcallus. In both cases, proembryos originated from single cells.They developed from starchy differentiated cells of a predeterminedtype. The polarity of the somatic proembryo was establishedfrom the first divisions and it was marked by precocious developmentof an easily recognizable suspensor. Other analogies with thedevelopment of the zygote are also emphasised. Vitis vinifera L.; grapevine; somatic embryogenesis; proembryogenesis; histology     

Characterization of eight polymorphic microsatellites in the shrew Crocidura suaveolens and its application to the study of insular populations of the French Atlantic coast

We developed eight polymorphic microsatellite loci to study the natural populations of Crocidura suaveolens, the lesser white‐toothed shrew. These loci are used in the study of insular populations of the French Atlantic coast where these shrews exhibit gigantism features that suggest an insular syndrome. These populations were threatened by the invasion of the rat Rattus norvegicus and the eradication of this alien pest in some islands was followed by a demographic expansion of the shrew populations. These first genetic results suggest that the shrew populations in the three studied islands are very differentiated.