A SIMPLE AND RAPID DETECTION BY PCR OF ENTEROPATHOGENIC ESCHERICHIA COLI IN NATURALLY CONTAMINATED VEGETABLES

Contaminated vegetables have been identified as one of the principal sources of foodborne illnesses. Escherichia coli is one of the bacteria that can contaminate vegetables and cause serious foodborne disease. The development of simple and rapid assays for detection of E. coli would enable official agencies and food industries to identify contaminated foodstuffs in a timelier manner. In this work, we detected E. coli contamination in four types of vegetables using a 24 h procedure. This method is very specific, rapid and simple to use in the laboratory. Indeed, the enrichment, DNA isolation and polymerase chain reaction (PCR) amplification procedures described here can also be used for detection of E. coli in other foods.

PRACTICAL APPLICATIONS

Foodborne disease remains an important public health threat worldwide; one of the most important food safety hazards is associated with raw vegetables. Several studies have found that products can support the growth of enteric bacterial pathogens such as Salmonella , Shigella and Escherichia coli . Culture techniques are universally recognized as the standard method for detecting pathogenic bacteria in foods. Bacteria are detected and subsequently identified by growth on solid selective culture media and by analysis of metabolic properties or serotyping. This process is lengthy and may last 5–10 days or more. In our investigation, the polymerase chain reaction (PCR) detection of E. coli in vegetables was realized within 24 h. The pre-enrichment step used in this study did not have any inhibiting effect on the PCR. Therefore, it became possible to rapidly and directly detect E. coli in raw vegetables by the PCR technique just by heating samples.     

A new large philisid (Mammalia,Chiroptera, Vespertilionoidea) from the late Early Eocene of Chambi,Tunisia

Abstract: Among the new dental remains from the late Early Eocene of Chambi (Kasserine area, Tunisia) is a large‐sized upper molar of a new bat species, Witwatia sigei nov. sp. (Chiroptera, Vespertilionoidea, Philisidae), described herein. The locality of Chambi has revealed evidence for an early appearance of two modern microchiropteran superfamilies in Africa: Dizzya exsultans, a Philisidae, which is considered to be an archaic Vespertilionoidea, and an indeterminate Rhinolophoidea. In addition to D. exsultans, the new species, W. sigei, is the second representative of the Philisidae in this locality. W. sigei extends back to the late Early Eocene the occurrence of the genus Witwatia, which was previously only reported from the early Late Eocene of the Fayum (BQ‐2, Egypt). By analogy with the largest extant microbats, the large size of Witwatia suggests a tendency to the opportunistic diet of this taxon, thereby contrasting with the strict insectivory characterizing primitive bats found in other continents in the same epoch.     

New stem elephant‐shrews (Mammalia,Macroscelidea) from the Eocene of Dur At‐Talah,Libya

Abstract: Two new primitive macroscelideans, Eotmantsoius perseverans gen. et sp. nov. and Nementchatherium rathbuni sp. nov. from the late Middle or Late Eocene locality of Dur At‐Talah, Libya, are described. Eotmantsoius is known from a single tooth and is characterized by low crown height, isolated conules, and lack of a preprotocrista and prehypocrista. Based on these characters, it appears to be more plesiomorphic than Chambius (late Early Eocene, Chambi, Tunisia), which was, to date, universally accepted as the oldest and most basal macroscelidean. Eotmantsoius appears, however, somewhat derived in having an entostyle, a pericone, a shorter mesial cingulum and larger intercusp valleys. The phylogenetic position of Eotmantsoius is unclear. The second new species, N. rathbuni, allows a reassessment of Nementchatherium. We suggest that it is the most derived of the herodotiines in having long preprotocrista and prehypocrista, reduced M2/m2, a robust entostyle twinned with the hypocone on M1 and the posterior aspect of the root of the maxillary jugal process placed along the length of M2. Nementchatherium rathbuni appears more derived than N. senarhense, from the Eocene locality of Bir El Ater, Algeria, in having smaller m2‐3 with no paraconid, a smaller hypoconulid on m2 and a more reduced talonid on m3 (with smaller hypoconid and entoconid). Nementchatherium rathbuni also has, distal to the m3, a coronoid canal. This character has commonly been proposed as a synapomorphy for paenungulates (e.g. proboscideans, sirenians and hyracoids); we investigate the possibility that it unites macroscelideans and paenungulates, as the superordinal clade Afrotheria suggests. Comparisons reveal that a coronoid canal also occurs in several nonafrotherian orders (lagomorphs, xenarthrans, artiodactyls and perissodactyls), suggesting that is not an exclusive synapomorphy for paenungulates plus macroscelideans. Moreover, the homology of the character within paenungulates is doubtful.     

Does sample length influence the shape of xylem embolism vulnerability curves? A test with the Cavitron spinning technique

The Cavitron spinning technique is used to construct xylem embolism vulnerability curves (VCs), but its reliability has been questioned for species with long vessels. This technique generates two types of VC: sigmoid ‘s’‐shaped and exponential, levelling‐off ‘r’‐shaped curves. We tested the hypothesis that ‘r’‐shaped VCs were anomalous and caused by the presence of vessels cut open during sample preparation. A Cavitron apparatus was used to construct VCs from samples of different lengths in species with contrasting vessel lengths. The results were compared with VCs obtained using other independent techniques. When vessel length exceeded sample length, VCs were ‘r’‐shaped and anomalous. Filling vessels cut open at both ends with air before measurement produced more typical ‘s’‐shaped VCs. We also found that exposing segments of 11 woody species in a Cavitron at the pressure measured in planta before sampling considerably increased the degree of embolism above the native state level for species with long vessels. We concluded that open vessels were abnormally more vulnerable to cavitation than intact vessels. We recommend restricting this technique to species with short conduits. The relevance of our conclusions for other spinning techniques is discussed.     

The blackflies (Diptera: Simuliidae) of Bioko (Republic of Equatorial Guinea) and the Gulf of Guinea with a description of the larvae of the 'Pomeroy' form of Simulium cervicornutum

Abstract.  Like many other organisms, Simuliidae often show a high degree of endemism on oceanic islands, and the Gulf of Guinea, including its islands, is a region of general biogeographical interest in view of the uniqueness of its flora and fauna. This paper presents a comprehensive review of the Simuliidae in the region, and is the first faunistic record of blackflies from Bioko. Simuliidae (larvae, pupae and neonate adults) were collected from Bioko and from around Mount Cameroon and compared with previous findings from Mount Cameroon, Príncipe and São Tomé. Twenty-seven species are known from the region. Twenty-five species have been recorded around Mount Cameroon, eight species on Bioko, three species on São Tomé and one species on Príncipe. Two taxonomic 'forms' (one on Bioko alone, and one on both Bioko and around Mount Cameroon) and one species (found only on São Tomé) are endemic to the region. A study of the variation in the morphology of Simulium cervicornutum revealed two morphotypes, one from Bioko and around Mount Cameroon and the other from the rest of Africa. The speciation and biogeography of the Simuliidae in the Gulf of Guinea are discussed.     

Rôle du Système Nerveux Sur la Prolifération Cellulaire des Blastèmes de Régénération de Membre de Triton (Pleurodeles Waltlii Michah)

Cellular proliferation of both epidermal and mesenchymal cells of denerved cone stage limb blastemas ( Pleurodeles waltlii Michah) was studied in vivo. The mitotic index and thymidine ³H incorporation (autoradiography following short term (1 hr) incubation and scintigraphy) show that denervation causes a significant decrease in the cellular proliferation (about 70% 4 days after denervation). Denervation affects first the mesenchymal cells, the proliferation of epidermal cells declines later. These results are discussed in term of cellular cycle.