27 research outputs found

    Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami)

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    Sexual differentiation across taxa may be due to genetic sex determination (GSD) and/or temperature sex determination (TSD). In many mammals, males are heterogametic (XY); whereas females are homogametic (XX). In most birds, the opposite is the case with females being heterogametic (ZW) and males the homogametic sex (ZZ). Many reptile spe- cies lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps). There has been speculation that Australian Brush-turkeys (Alectura lathami) exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP) and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Austra- lian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae

    The dominant Anopheles vectors of human malaria in Africa, Europe and the Middle East: occurrence data, distribution maps and bionomic précis

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    <p>Abstract</p> <p>Background</p> <p>This is the second in a series of three articles documenting the geographical distribution of 41 dominant vector species (DVS) of human malaria. The first paper addressed the DVS of the Americas and the third will consider those of the Asian Pacific Region. Here, the DVS of Africa, Europe and the Middle East are discussed. The continent of Africa experiences the bulk of the global malaria burden due in part to the presence of the <it>An. gambiae </it>complex. <it>Anopheles gambiae </it>is one of four DVS within the <it>An. gambiae </it>complex, the others being <it>An. arabiensis </it>and the coastal <it>An. merus </it>and <it>An. melas</it>. There are a further three, highly anthropophilic DVS in Africa, <it>An. funestus</it>, <it>An. moucheti </it>and <it>An. nili</it>. Conversely, across Europe and the Middle East, malaria transmission is low and frequently absent, despite the presence of six DVS. To help control malaria in Africa and the Middle East, or to identify the risk of its re-emergence in Europe, the contemporary distribution and bionomics of the relevant DVS are needed.</p> <p>Results</p> <p>A contemporary database of occurrence data, compiled from the formal literature and other relevant resources, resulted in the collation of information for seven DVS from 44 countries in Africa containing 4234 geo-referenced, independent sites. In Europe and the Middle East, six DVS were identified from 2784 geo-referenced sites across 49 countries. These occurrence data were combined with expert opinion ranges and a suite of environmental and climatic variables of relevance to anopheline ecology to produce predictive distribution maps using the Boosted Regression Tree (BRT) method.</p> <p>Conclusions</p> <p>The predicted geographic extent for the following DVS (or species/suspected species complex*) is provided for Africa: <it>Anopheles </it>(<it>Cellia</it>) <it>arabiensis</it>, <it>An. </it>(<it>Cel.</it>) <it>funestus*</it>, <it>An. </it>(<it>Cel.</it>) <it>gambiae</it>, <it>An. </it>(<it>Cel.</it>) <it>melas</it>, <it>An. </it>(<it>Cel.</it>) <it>merus</it>, <it>An. </it>(<it>Cel.</it>) <it>moucheti </it>and <it>An. </it>(<it>Cel.</it>) <it>nili*</it>, and in the European and Middle Eastern Region: <it>An. </it>(<it>Anopheles</it>) <it>atroparvus</it>, <it>An. </it>(<it>Ano.</it>) <it>labranchiae</it>, <it>An. </it>(<it>Ano.</it>) <it>messeae</it>, <it>An. </it>(<it>Ano.</it>) <it>sacharovi</it>, <it>An. </it>(<it>Cel.</it>) <it>sergentii </it>and <it>An. </it>(<it>Cel.</it>) <it>superpictus*</it>. These maps are presented alongside a bionomics summary for each species relevant to its control.</p

    Karyotype results for Australian Brush-turkeys.

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    <p>G-band karyotype images without microchromosomes of A) female <i>A</i>. <i>lathami</i> demonstrating heterogametic ZW sex chromosomes and B) male <i>A</i>. <i>lathami</i> demonstrating homogametic ZZ sex chromosomes, C) G-band sex chromosomes of one female and two male <i>A</i>. <i>lathami</i>, and D) a C-band female metaphase image demonstrating weak to absent C-banding on the Z chromosome and complete C-banding on the W chromosome. For A and B, the numbers of corresponding chromosomes from the <i>G</i>. <i>gallus domesticus</i> karyotype are provided parenthetically.</p

    Karyotype results for Australian Brush-turkeys.

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    <p>G-band karyotype images without microchromosomes of A) female <i>A</i>. <i>lathami</i> demonstrating heterogametic ZW sex chromosomes and B) male <i>A</i>. <i>lathami</i> demonstrating homogametic ZZ sex chromosomes, C) G-band sex chromosomes of one female and two male <i>A</i>. <i>lathami</i>, and D) a C-band female metaphase image demonstrating weak to absent C-banding on the Z chromosome and complete C-banding on the W chromosome. For A and B, the numbers of corresponding chromosomes from the <i>G</i>. <i>gallus domesticus</i> karyotype are provided parenthetically.</p

    Atypical expression of HGAL in isolated atypical follicles.

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    <p>An axillary lymph node in a 53-year old woman (case 2) shows a single atypical follicle with pleomorphic large cells overexpressing HGAL (A and B). Sections of the tonsil in a 6-year old boy stained with HGAL, show preservation of overall architecture with numerous normal reactive follicles and a gradient of HGAL staining with higher intensity in the dark zone. In the atypical follicle (indicated by arrow in panel D), HGAL staining is abnormal and shows overexpression throughout the affected follicle (C and D).</p
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