396 research outputs found

    Dental eruption and growth in Hyracoidea (Mammalia, Afrotheria)

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    We investigated dental homologies, development, and growth in living and fossil hyracoids, and tested if hyracoids and other mammals show correlations between eruption patterns, gestation time, and age at maturity. Unlike living species, fossil hyracoids simultaneously possess replaced P1 and canine teeth. Fossil species also have shorter crowns, an upper and lower I3 locus, an upper I2, and a hypoconulid on m3. Prenatal specimens of the living Procavia capensis\textit{Procavia capensis} and Heterohyrax brucei\textit{Heterohyrax brucei} show up to three tooth buds posterior to upper dI1 and anterior to the seven upper cheek teeth that consistently erupt; these include an anterior premolar but not a canine. Most lower cheek teeth finish eruption during growth in hyracoids, not after growth as in most other afrotherians. All hyracoids show the m1 at (lower) or near (upper) the beginning of eruption of permanent teeth; M3/m3 is the last permanent tooth to erupt. The living P. capensis erupts most lower antemolar loci before m2. In contrast, fossil hyraxes erupt lower antemolars after m2. While the early eruption of antemolars correlates with increased gestation time and age at maturity in primates and Tupaia\textit{Tupaia} (i.e., "Schultz's Rule"), and while modern hyraxes resemble some anthropoid primates in exhibiting long gestation and eruption of antemolars at or before molars, eruption patterns do not significantly co-vary with either life history parameter among afrotherians sampled so far. However, we do observe a shift in eruption timing and crown height in Procavia\textit{Procavia} relative to fossil hyracoids, mirroring observations recently made for other ungulate-grade mammals.Collection of Fayum hyracoids has been funded by U.S. National Science Foundation grants to E. L. Simons (BCS-0114856), to ELS and E. R. Seiffert (BCS- 0416164), to ERS (BCS-0819186), and to ERS, J. G. Fleagle, G. F. Gunnell, and D. M. Boyer (BCS-1231288). Fieldwork was undertaken in collaboration with the Egyptian Mineral Resources Authority and the Egyptian Geological Museum, and was managed by P. Chatrath. RJA, LH, and DP acknowledge support from the Leverhulme Trust and the Department of Zoology, University of Cambridge. We thank C. Riddle and V. Yarborough for access to fossils and fossil preparation, and C. Soubiran for help with segmentation of extant hyrax CT scans. Some CTscan data presented in this work were produced thanks to the imaging facilities of the MRI Platform and of the LabEx CeMEB (Montpellier)

    Establishment and optimization of genomic selection to accelerate the domestication and improvement of intermediate wheatgrass

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    Citation: Zhang, X., Sallam, A., Gao, L., Kantarski, T., Poland, J., DeHaan, L. R., . . . Anderson, J. A. (2016). Establishment and optimization of genomic selection to accelerate the domestication and improvement of intermediate wheatgrass. Plant Genome, 9(1). doi:10.3835/plantgenome2015.07.0059Intermediate wheatgrass (IWG) is a perennial species and has edible and nutritious grain and desirable agronomic traits, including large seed size, high grain yield, and biomass. It also has the potential to provide ecosystem services and an economic return to farmers. However, because of its allohexaploidy and self-incompatibility, developing molecular markers for genetic analysis and molecular breeding has been challenging. In the present study, using genotyping-by-sequencing (GBS) technology, 3436 genomewide markers discovered in a biparental population with 178 genets, were mapped to 21 linkage groups (LG) corresponding to 21 chromosomes of IWG. Genomic prediction models were developed using 3883 markers discovered in a breeding population containing 1126 representative genets from 58 half-sib families. High predictive ability was observed for seven agronomic traits using cross-validation, ranging from 0.46 for biomass to 0.67 for seed weight. Optimization results indicated that 8 to 10 genets from each half-sib family can form a good training population to predict the breeding value of their siblings, and 1600 genomewide markers are adequate to capture the genetic variation in the current breeding population for genomic selection. Thus, with the advances in sequencing-based marker technologies, it was practical to perform molecular genetic analysis and molecular breeding on a new and challenging species like IWG, and genomic selection could increase the efficiency of recurrent selection and accelerate the domestication and improvement of IWG.A. © Crop Science Society of America

    Craniodental Morphology and Systematics of a New Family of Hystricognathous Rodents (Gaudeamuridae) from the Late Eocene and Early Oligocene of Egypt

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    BACKGROUND: Gaudeamus is an enigmatic hystricognathous rodent that was, until recently, known solely from fragmentary material from early Oligocene sites in Egypt, Oman, and Libya. Gaudeamus' molars are similar to those of the extant cane rat Thryonomys, and multiple authorities have aligned Gaudeamus with Thryonomys to the exclusion of other living and extinct African hystricognaths; recent phylogenetic analyses have, however, also suggested affinities with South American caviomorphs or Old World porcupines (Hystricidae). METHODOLOGY/PRINCIPAL FINDINGS: Here we describe the oldest known remains of Gaudeamus, including largely complete but crushed crania and complete upper and lower dentitions. Unlike younger Gaudeamus species, the primitive species described here have relatively complex occlusal patterns, and retain a number of plesiomorphic features. Unconstrained parsimony analysis nests Gaudeamus and Hystrix within the South American caviomorph radiation, implying what we consider to be an implausible back-dispersal across the Atlantic Ocean to account for Gaudeamus' presence in the late Eocene of Africa. An analysis that was constrained to recover the biogeographically more plausible hypothesis of caviomorph monophyly does not place Gaudeamus as a stem caviomorph, but rather as a sister taxon of hystricids. CONCLUSIONS/SIGNIFICANCE: We place Gaudeamus species in a new family, Gaudeamuridae, and consider it likely that the group originated, diversified, and then went extinct over a geologically brief period of time during the latest Eocene and early Oligocene in Afro-Arabia. Gaudeamurids are the only known crown hystricognaths from Afro-Arabia that are likely to be aligned with non-phiomorph members of that clade, and as such provide additional support for an Afro-Arabian origin of advanced stem and basal crown members of Hystricognathi

    Placenta increta causing hemoperitoneum in the 26th week of pregnancy: a case report

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    Abstract Introduction Placenta increta is a serious complication of pregnancy. We describe a case leading to uterine rupture associated with massive intra-abdominal hemorrhage. Case presentation A 34-year-old Caucasian Albanian woman, gravida 2, para 1, was admitted to the emergency department of our hospital for acute abdominal pain associated with profound secondary anemia. An anatomopathological diagnosis of placenta increta destruens was made. An urgent hysterectomy was performed after resuscitation procedures, applied due to the severe anemia and the abdominal drama accompanying the case. Intra-operatively, a uterus-saving procedure was found to be impossible, and hysterectomy remained the only surgical option. The uterine structures were sent for further microscopic evaluation. On histological examination, deep trophoblastic infiltration of the uterine wall was observed, justifying the surgeon's decision. Our patient received blood transfusions and antibiotics. Her sutures were removed on the eighth postoperative day and she was discharged the following day in a stable condition. Conclusion This case, describing a patient with uterine rupture and massive hemorrhage, illustrates a serious and potentially fatal complication of placenta previa. In such cases, surgery is essential, and hysterectomy may be the only viable option.</p

    Hystricognathy vs Sciurognathy in the Rodent Jaw: A New Morphometric Assessment of Hystricognathy Applied to the Living Fossil Laonastes (Diatomyidae)

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    While exceptional for an intense diversification of lineages, the evolutionary history of the order Rodentia comprises only a limited number of morphological morphotypes for the mandible. This situation could partly explain the intense debates about the taxonomic position of the latest described member of this clade, the Laotian rock rat Laonastes aenigmamus (Diatomyidae). This discovery has re-launched the debate on the definition of the Hystricognathi suborder identified using the angle of the jaw relative to the plane of the incisors. Our study aims to end this ambiguity. For clarity, it became necessary to revisit the entire morphological diversity of the mandible in extant and extinct rodents. However, current and past rodent diversity brings out the limitations of the qualitative descriptive approach and highlights the need for a quantitative approach. Here, we present the first descriptive comparison of the masticatory apparatus within the Ctenohystrica clade, in combining classic comparative anatomy with morphometrical methods. First, we quantified the shape of the mandible in rodents using 3D landmarks. Then, the analysis of osteological features was compared to myological features in order to understand the biomechanical origin of this morphological diversity. Among the morphological variation observed, the mandible of Laonastes aenigmamus displays an intermediate association of features that could be considered neither as sciurognathous nor as hystricognathous

    Sero-survey of rubella IgM antibodies among children in Jos, Nigeria

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    Sero-survey of rubella IgM antibodies was carried out among children aged 0-10 years in Jos, Nigeria. Blood samples were collected from the subjects and sera extracted. Of the 93(100%) assayed for the rubella IgM antibody, 42(45.2%) were seropositive for rubella IgM antibody while 51(54.8%) were seronegative. A breakdown of the seropositive subjects reveals that 14(15.1%) of the infected children were males while 28(30.1%) were females. Those subjects within the age groups of 1-2, 3-4 and 5-6 years had the highest prevalence of 8(8.6%) followed by those within the age groups of 7-8, 9-10 years with 7(7.5%). Blood transfusion as a risk factor did not show any significant influence on the status of the subjects. The demographic data of the mothers of the subjects were also linked with the seropositivity of the children

    Spatial heterogeneity of habitat suitability for Rift Valley fever occurrence in Tanzania: an ecological niche modelling approach

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    Despite the long history of Rift Valley fever (RVF) in Tanzania, extent of its suitable habitat in the country remains unclear. In this study we investigated potential effects of temperature, precipitation, elevation, soil type, livestock density, rainfall pattern, proximity to wild animals, protected areas and forest on the habitat suitability for RVF occurrence in Tanzania. Presence-only records of 193 RVF outbreak locations from 1930 to 2007 together with potential predictor variables were used to model and map the suitable habitats for RVF occurrence using ecological niche modelling. Ground-truthing of the model outputs was conducted by comparing the levels of RVF virus specific antibodies in cattle, sheep and goats sampled from locations in Tanzania that presented different predicted habitat suitability values. Habitat suitability values for RVF occurrence were higher in the northern and central-eastern regions of Tanzania than the rest of the regions in the country. Soil type and precipitation of the wettest quarter contributed equally to habitat suitability (32.4% each), followed by livestock density (25.9%) and rainfall pattern (9.3%). Ground-truthing of model outputs revealed that the odds of an animal being seropositive for RVFV when sampled from areas predicted to be most suitable for RVF occurrence were twice the odds of an animal sampled from areas least suitable for RVF occurrence (95% CI: 1.43, 2.76, p < 0.001). The regions in the northern and central-eastern Tanzania were more suitable for RVF occurrence than the rest of the regions in the country. The modelled suitable habitat is characterised by impermeable soils, moderate precipitation in the wettest quarter, high livestock density and a bimodal rainfall pattern. The findings of this study should provide guidance for the design of appropriate RVF surveillance, prevention and control strategies which target areas with these characteristics
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