Integrative identification and molecular phylogeny of dagger and needle nematodes associated with cultivated olive in Tunisia

The occurrence and geographic distribution of longidorid nematode species inhabiting the rhizosphere of cultivated olive (cvs. Chemlali and Chétoui) in Tunisia were investigated. Morphological and morphometrical studies identified three Longidorus and six Xiphinema species, with frequencies of prevalence as following: Longidorus africanus (23.0 %), L. euonymus (4.5 %), L. glycines (13.7 %), Xiphinema conurum (13.7 %), X. italiae (36.4 %), X. meridianum (13.7 %), X. pachtaicum (18.2 %), X. robbinsi (9.1 %), and Xiphinema sp. (4.5 %). The three Longidorus species were reported for the first time in Tunisia, in addition to two species of Xiphinema (viz. X. meridianum and X. robbinsi). Molecular characterisation using D2-D3 expansion regions of 28S rRNA and ITS1-rRNA was carried out and Bayesian inference analysis was used to reconstruct phylogenetic relationships among these species and with other longidorids. Twenty-five new D2-D3 of 28S rRNA gene sequences were obtained in the present study, seven for Longidorus and 18 for Xiphinema spp., as well as 14 new ITS1 rRNA gene sequences (seven for Longidorus and seven for Xiphinema spp.).     

Morphological and molecular characterisation of Pratylenchus oleae n. sp. (Nematoda: Pratylenchidae) parasitizing wild and cultivated olives in Spain and Tunisia

A new mono-sexual root-lesion nematode species, Pratylenchus oleae n. sp., parasitizing roots of olive plants cv. Koroneiki in commercial fields at Ouled Chamekh (central Tunisia), and wild and cultivated olive (cv. Picual) plants in Agua Amarga (southern Spain) is described. The new species is characterised by the female having a lip region slightly offset and bearing three annuli, stylet 16.5 (14.5-17.0) μm long, with prominent rounded knobs, pharyngeal overlapping rather long (22–36) μm, lateral fields areolated and with four incisures and diagonal lines in middle band, spermatheca rounded but non-functional, tail short, conoid-rounded to subcylindrical, usually annulated terminus, males unknown, and a specific D2-D3, ITS1, 18S-rRNA, hsp90 and COI sequences. Morphologically this species is related to P. cruciferus, P. delattrei, and P. kumamotoensis. The results of the phylogenetic analysis based on sequences of the D2-D3 expansion regions of 28S, partial 18S and ITS rRNA genes confirmed the close relationship of P. oleae n. sp. with P. dunensis, P. penetrans, P. pinguicaudatus, from which was clearly separated. A PCR-based diagnostic assay was also developed for identification of P. oleae n. sp. using the species-specific primers Poleae_fw1_4 and Poleae_rv1 that amplify a 547-bp fragment in the internal transcribed spacer (ITS1) region of ribosomal DNA, which clearly separate from other root-lesion nematodes damaging olive such as P. penetrans and P. vulnus.     

Light-scattering study of the structure of aggregates and gels formed by heat-denatured whey protein isolate and beta-lactoglobulin at neutral pH

The structure of aggregates and gels formed by heat-denatured whey protein isolate (WPI) has been studied at pH 7 and different ionic strengths using light scattering and turbidimetry. The results were compared with those obtained for pure beta-lactoglobulin (beta-Lg). WPI aggregates were found to have the same self-similar structure as pure beta-Lg aggregates. WPI formed gels above a critical concentration that varied from close to 100 g/L in the absence of added salt to about 10 g/L at 0.2 M NaCl. At low ionic strength (<0.05 M NaCl) homogeneous transparent gels were formed, while at higher ionic strength the gels became turbid but had the same self-similar structure as reported earlier for pure beta-Lg. The length scale characterizing the heterogeneity of the gels increased exponentially with increasing NaCl concentration for both WPI and pure beta-Lg, but the increase was steeper for the former.     

The Marek��s disease virus (MDV) protein encoded by the UL17 ortholog is essential for virus growth

Marek’s disease virus type 1 (MDV-1) shows a strict dependency on the direct cell-to-cell spread for its propagation in cell culture. As MDV-1 shows an impaired nuclear egress in cell culture, we wished to address the characterization of capsid/tegument genes which may intervene in the maturation of intranuclear capsids. Orthologs of UL17 are present in all herpesviruses and, in all reported case, were shown to be essential for viral growth, playing a role in capsid maturation and DNA packaging. As only HSV-1 and PrV UL17 proteins have been characterized so far, we wished to examine the role of MDV-1 pUL17 in virus replication. To analyze MDV-1 UL17 gene function, we created deletion mutants or point mutated the open reading frame (ORF) to interrupt its coding phase. We established that a functional ORF UL17 is indispensable for MDV-1 growth. We chose to characterize the virally encoded protein by tagging the 729 amino-acid long protein with a repeat of the HA peptide that was fused to its C-terminus. Protein pUL17 was identified in infected cell extracts as an 82 kDa protein which localized to the nucleus, colocalizing with VP5, the major capsid protein, and VP13/14, a major tegument protein. By using green fluorescent protein fusion and HA tagged proteins expressed under the cytomegalovirus IE gene enhancer/promoter (P_{CMV IE}), we showed that MDV-1 pUL17 nuclear distribution in infected cells is not an intrinsic property. Although our results strongly suggest that another viral protein retains (or relocate) pUL17 to the nucleus, we report that none of the tegument protein tested so far were able to mediate pUL17 relocation to the nucleus.