Differences in skin characteristics in European (Large White) and Caribbean (Creole) growing pigs with reference to thermoregulation

The effects of breed and season on histological skin characteristics were studied at the experimental facilities of INRA in Guadeloupe (16° Lat. N., 61° Long. W.) in two replicates using a total of 20 Creole (CR) and 20 Large White (LW) pigs. The first replicate was carried out during the warm season (i.e., between February and April) and the second during the hot season (i.e., between August and October). In the warm season, ambient temperature and relative humidity averaged 25.3 °C and 86.0%, respectively. The corresponding values for the hot season were 27.9 °C and 83.6%. At 90 kg BW, all pigs were slaughtered and a 2 to 4 cm$^{2}$ sample of cutaneous tissue from the back region (i.e., at the last dorsal rib level) was taken from each animal before scalding and dehairing. Slices were stained with trichrome blue staining and the thickness of the epidermis and dermis were determined. The density and surface of the sweat glands (SG) were also determined. The mast cell density was measured using slices stained with Giemsa. Epidermis thickness was not affected by breed or season and averaged 55 $\mu$m. However, dermis thickness was significantly higher in CR than in LW pigs (3.60 vs. 3.13 mm; $P < 0$.01) but it was not influenced by season (3.36 mm on average; $P$ = 0.17). The density of SG was significantly higher in CR than in LW pigs (32.0 vs. 25.4 SG per mm$^{2}$; $P < 0$.01) but their surface area was lower in CR than in LW pigs (106 vs. 263 $\times$ 10$^{-3 }$$\mu$m$^{2}$ per mm$^{2}$; $P < 0$.01). The SG density tended to be higher in the hot than in the warm season (30.4 vs. 26.9 SG per mm$^{2}$; $P$ = 0.0971). Mast cell density in the dermis was found to be higher in CR than in LW pigs (2.52 vs. 1.38 mast cells per mm$^{2}$; $P < 0$.01). Irrespective of the breed, mast cell density was higher during the hot than the warm season (2.22 vs. 1.68 mast cells per mm$^{2}$; $P < 0$.01). In conclusion, our study suggests that the differences in skin histology and/or sweat gland histometry could partly explain the better heat tolerance in CR pigs.Les effets du type génétique et de la saison sur les caractéristiques histologiques de la peau ont été étudiés l'INRA de Guadeloupe (16° Lat. N., 61° Long. W.) sur un total de 20 porcs Créole (CR) et 20 porcs Large White (LW) répartis en deux répétitions. La première répétition s'est déroulée au cours de la saison fraîche (entre février et avril) et la seconde au cours de la saison chaude (entre août et octobre). En saison fraîche, la température et l'humidité relative moyenne étaient respectivement de 25,3 °C et 86,0 %. Les valeurs correspondantes pour la saison chaude étaient de 27,9 °C et 83,6 %. Au poids vif de 90 kg, tous les porcs ont été abattus et un échantillon de peau de 2 à 4 cm$^{2}$ a été prélevé au niveau du dos (i.e., au niveau de la dernière côte dorsale) avant l'échaudage et l'épilation. Les épaisseurs de l'épiderme et du derme ont été déterminées sur des coupes de peau colorées au trichrome bleu. La densité et la surface des glandes sudoripares (SG) ont également été mesurées. La densité des mastocytes a été déterminée sur des coupes colorées au Giemsa. L'épaisseur de l'épiderme n'est pas affectée par le type génétique ou par la saison (55 $\mu$m en moyenne). En revanche, l'épaisseur du derme est significativement plus importante chez le CR comparativement au LW (3,60 vs. 3,13 mm ; $P < 0$,01) mais n'est pas influencée par la saison (3,36 mm en moyenne ; $P$ = 0,17). La densité des glandes sudoripares est significativement plus importante chez le porc CR par rapport au LW (32,0 vs. 25,4 SG par mm$^{2}$ ; $P < 0$,01) mais leur surface est plus faible chez le porc CR par rapport au LW (106 vs. 263 $\times$ 10$^{-3}~\mu$m$^{2}$ par mm$^{2}$ ; $P < 0$,01). La densité des SG tend à être plus élevée en saison chaude comparativement à la saison fraîche (30,4 vs. 26,9 SG par mm$^{2}$ ; $P$ = 0,097). Dans le derme, la densité des mastocytes est significativement plus élevée chez le porc CR par rapport au LW (2,52 vs. 1,38 mastocytes par mm$^{2}$ ; $P < 0$,01). Quelque soit la race, la densité des mastocytes est plus importante au cours de la saison chaude comparativement à la saison fraîche (2,22 vs. 1,68 mastocytes par mm$^{2}$ ; $P < 0$,01). En conclusion, notre étude montre que les différences d'histologie de la peau ou des caractéristiques des glandes sudoripares entre les deux types génétiques pourraient en partie expliquer la meilleure adaptation du porc CR

Structure et fonction d'une cytokinine oxydase / déshydrogénase (modifications d'enzymes)

L'objet de cette thèse est l'étude d'une cytokinine oxydase/déshydrogénase du maïs (ZmCKO1). La flavoenzyme CKO catalyse la dégradation des hormones végétales de type cytokinines, dérivés N6-substitués de l'adénine. Il s'agissait de déterminer l'importance du rôle de CKO dans le développement des plantes, la structure de l'enzyme et l'acide aminé clef dans la réaction enzymatique, le mécanisme réactionnel en présence de deux types d'inhibiteurs différents, la localisation des sites catalytiques oxydase et déshydrogénase?Afin de mieux comprendre le rôle de la CKO dans l'homéostasie des cytokinines, la teneur en hormone a été modifiée en surexprimant ZmCKO1 de manière constitutive chez Arabidopsis thaliana. Les effets phénotypiques et les teneurs en cytokinines ont été déterminés de même que l'expression de gènes endogènes impliqués dans la biosynthèse, la dégradation et la signalisation des cytokinines. ZmCKO1 a été exprimée dans la levure Yarrowia lipolytica, purifiée et ses propriétés moléulaires et cinétiques caractérisées ; elle a été cristallisée et sa structure obtenue avec une résolution de 1,95 Å en présence de deux types d'inhibiteurs, des analogues d'adénine N6-substituée et de cytokinines de type urée. Des expériences de mutagenèse dirigée confirment le rôle clef de Asp169 dans la catalyse enzymatique et indiquent l'importance d'autres résidus d'acide aminé dans l'interaction avec le substrat et les accepteurs d'électrons. Un mécanisme réactionnel de type ping-pong est proposé, la molécule organique acceptrice d'électrons, tout comme l'oxygène, se liant au site actif en face de l'azote N5 du FAD.The Ph.D. thesis is focused on the study of cytokinin oxidase/dehydrogenase from maize (ZmCKO1). CKO is a flavoenzyme and catalyzes the degradation of plant hormones cytokinins, which are N6-substituted adenine derivatives. Four questions were adressed: (i) how important is the role of CKO in plant development? (ii) what is the structure of the enzyme and what is the key amino acid residue in enzyme reaction? (iii) what is the mechanism of CKO inhibition with two different types of synthetic cytokinin derivatives and whether is the inhibition accompanied by enzyme modification? (iv) are the oxidase and dehydrogenase catalytic sites different?To unravel the role of CKO in cytokinin homeostasis, content of the hormone was altered by constitutive overexpression of ZmCKO1 in Arabidopsis thaliana. Effects on phenotype and changes in levels of cytokinins were determined as well as expression of endogenous genes related to cytokinin biosynthesis, degradation and signaling. ZmCKO1 was further expressed in the yeast Yarrowia lipolytica, purified, and its molecular and kinetic properties were characterized; it was further crystallized and its structure solved up to 1.95 Å resolution in presence of two types of inhibitors - N6-substituted adenine and urea-type cytokinin analogs. Site-directed mutagenesis confirmed the key role of Asp169 in enzyme catalysis and revealed the importance of some other amino acid residues in the interaction with substrate and electron acceptors. This work leads to the proposal that the CKO reaction proceeds through a pingpong mechanism and that organic electron acceptor as well as oxygen bind in the active site in front of nitrogen N5 of FAD.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

WheatExp: an RNA-seq expression database for polyploid wheat.

BackgroundFor functional genomics studies, it is important to understand the dynamic expression profiles of transcribed genes in different tissues, stages of development and in response to environmental stimuli. The proliferation in the use of next-generation sequencing technologies by the plant research community has led to the accumulation of large volumes of expression data. However, analysis of these datasets is complicated by the frequent occurrence of polyploidy among economically-important crop species. In addition, processing and analyzing such large volumes of sequence data is a technical and time-consuming task, limiting their application in functional genomics studies, particularly for smaller laboratories which lack access to high-powered computing infrastructure. Wheat is a good example of a young polyploid species with three similar genomes (97 % identical among homoeologous genes), rapidly accumulating RNA-seq datasets and a large research community.DescriptionWe present WheatExp, an expression database and visualization tool to analyze and compare homoeologue-specific transcript profiles across a broad range of tissues from different developmental stages in polyploid wheat. Beginning with publicly-available RNA-seq datasets, we developed a pipeline to distinguish between homoeologous transcripts from annotated genes in tetraploid and hexaploid wheat. Data from multiple studies is processed and compiled into a database which can be queried either by BLAST or by searching for a known gene of interest by name or functional domain. Expression data of multiple genes can be displayed side-by-side across all expression datasets providing immediate access to a comprehensive panel of expression data for specific subsets of wheat genes.ConclusionsThe development of a publicly accessible expression database hosted on the GrainGenes website - http://wheat.pw.usda.gov/WheatExp/ - coupled with a simple and readily-comparable visualization tool will empower the wheat research community to use RNA-seq data and to perform functional analyses of target genes. The presented expression data is homoeologue-specific allowing for the analysis of relative contributions from each genome to the overall expression of a gene, a critical consideration for breeding applications. Our approach can be expanded to other polyploid species by adjusting sequence mapping parameters according to the specific divergence of their genomes

Non-disclosure of drug injection practices as a barrier to HCV testing: results from the PrebupIV community-based research study

Abstract Background Hepatitis C virus (HCV) infection prevalence is particularly high in people who inject drugs (PWID), a population that faces many barriers to HCV testing and care. A better understanding of the determinants of access to HCV testing is needed to improve their engagement in the HCV care cascade. We used data from a cross-sectional survey of people who inject drugs, mainly opioids, to identify factors associated with recent HCV testing. Methods Self-reported data on HCV antibody testing were analyzed for 550 of the 557 PWID enrolled in PrebupIV, a French cross-sectional community-based survey which assessed PWID acceptability of injectable buprenorphine as a treatment. Factors associated with recent (i.e., in the previous six months) HCV antibody testing were identified performing multivariable logistic regression. Results Among the study sample, 79% were men and 31% reported recent HCV antibody testing. Multivariable analysis found that PWID who did not disclose their injection practices to anyone (aOR [95% CI] 0.31 [0.12,0.82], p = 0.018), older PWID (aOR [95% CI] 0.97 [0.95,1.00], p = 0.030) and employed respondents (aOR [95% CI] 0.58 [0.37,0.92], p = 0.019) were all less likely to report recent HCV testing. No association was found between opioid agonist therapy and HCV testing. Conclusions Our findings suggest that non-disclosure of injection practices, employment and age were all barriers to HCV antibody testing. Preventing stigma around injection practices, developing the HCV testing offer in primary care and addiction care services, and training healthcare providers in HCV care management could improve HCV testing and therefore, the HCV care cascade in PWID