DOCSLIB.ORG

Evidence for Emergence of Sex-Determining Gene(S) in a Centromeric Region in Vasconcellea Parviflora

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Evidence for Emergence of Sex-Determining Gene(S) in a Centromeric Region in Vasconcellea Parviflora INVESTIGATION Evidence for Emergence of Sex-Determining Gene(s) in a Centromeric Region in Vasconcellea parviflora Marina Iovene,*,† Qingyi Yu,‡ Ray Ming,§,** and Jiming Jiang*,1 *Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706, †Consiglio Nazionale delle Ricerche–Institute of Biosciences and BioResouces, Bari 70126, Italy, ‡Department of Plant Pathology and Microbiology, Texas A&M AgriLife Research Center, Texas A&M University System, Dallas, Texas 75252, §Department of Plant Biology, University of Illinois at Urbana–Champaign, Urbana, Illinois 61801, and **Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China ABSTRACT Sex chromosomes have been studied in many plant and animal species. However, few species are suitable as models to study the evolutionary histories of sex chromosomes. We previously demonstrated that papaya (Carica papaya)(2n =2x = 18), a fruit tree in the family Caricaceae, contains recently emerged but cytologically heteromorphic X/Y chromosomes. We have been intrigued by the possible presence and evolution of sex chromosomes in other dioecious Caricaceae species. We selected a set of 22 bacterial artificial chromosome (BAC) clones that are distributed along the papaya X/Y chromosomes. These BACs were mapped to the meiotic pachytene chromosomes of Vasconcellea parviflora (2n =2x = 18), a species that diverged from papaya 27 million years ago. We demonstrate that V. parviflora contains a pair of heteromorphic X/Y chromosomes that are homologous to the papaya X/Y chromosomes. The comparative mapping results revealed that the male-specific regions of the Y chromosomes (MSYs) probably initiated near the centromere of the Y chromosomes in both species. The two MSYs, however, shared only a small chromosomal domain near the centromere in otherwise rearranged chromosomes. The V. parviflora MSY expanded toward the short arm of the chromosome, whereas the papaya MSY expanded in the opposite direction. Most BACs mapped to papaya MSY were not located in V. parviflora MSY, revealing different DNA compositions in the two MSYs. These results suggest that mutation of gene(s) in the centromeric region may have triggered sex chromosome evolution in these plant species. KEYWORDS FISH; centromere; heterochromatin; sex chromosome ETEROMORPHIC sex chromosomes (X/Y, Z/W) evolved homologous XY systems and all birds have homologous ZW Hfrom pairs of autosomes (Ming et al. 2011; Bachtrog systems (Graves 2008). Thus, these sex chromosomes, sur- 2013; Charlesworth 2013). It is generally accepted that sex prisingly, appear to have evolved only once in each of these chromosome evolution is initiated by the emergence of a sex- two major evolutionary clades. determining locus. Suppression of recombination surround- Compared to mammals and birds, sex chromosomes have ing the sex-determining locus, which favored the linkage of emerged more frequently in several other eukaryotic lineages, the sex-determining alleles with sexually antagonistic alleles, including plants. Sex chromosomes have been reported in at caused the decay of the Y/W chromosomes and resulted in least 48 plant species across 20 different families, including a pair of heteromorphic sex chromosomes (Ming et al. 2011; both X/Y and Z/W systems (Ming et al. 2011; Kumar et al. Bachtrog 2013; Charlesworth 2013). Sex chromosomes evolved 2014). Sex chromosomes in some plant species were identi- independently in different eukaryotic lineages. The mammalian fied using genetic mapping-based approaches. However, cyto- X chromosome and the bird Z chromosome evolved from dif- genetic data are not available from most of these species. Thus, ferent portions of the ancestral genome (Bellott et al. 2010; it is unclear whether heteromorphic chromosomes have al- Cortez et al. 2014). Interestingly, all therian mammals have ready developed in these species, such as asparagus (Asparagus officinalis) (Telgmann-Rauber et al. 2007), Populus (Populus Copyright © 2015 by the Genetics Society of America trichocarpa)(Yinet al. 2008), and spinach (Spinacia oleracea) doi: 10.1534/genetics.114.173021 (Yamamoto et al. 2014). Heteromorphic sex chromosomes Manuscript received October 4, 2014; accepted for publication November 26, 2014; published Early Online December 5, 2014. were revealed cytologically in several plant species (Yamato Supporting information is available online at http://www.genetics.org/lookup/suppl/ et al. 2007; Zhang et al. 2008; Sousa et al. 2013), including, doi:10.1534/genetics.114.173021/-/DC1. 1Corresponding author: Department of Horticulture, 1575 Linden Dr., Room 409A, Silene latifolia, which is one of the best-studied model plant University of Wisconsin, Madison, WI 53706. E-mail: [email protected] species with well-differentiated X/Y chromosomes (Vyskot Genetics, Vol. 199, 413–421 February 2015 413 and Hobza 2004; Macas et al. 2011). Multiple sex chromo- somes, such as XY1Y2, were also reported in several plant species (Hizume et al. 1988; Howell et al. 2009; Mariotti et al. 2009; Navajas-Perez et al. 2009). Most of the plant species with sex chromosomes have not been sequenced. We have limited knowledge of the evolutionary histories of plant sex chromosomes because of scarce genomic resources and a lack of cytological and comparative studies of geneti- cally related plant species with sex chromosomes. Most species in the Caricaceae family are dioecious. Therefore, dioecy likely represents the ancestral sexual state in this family (Charlesworth 2013). Papaya (Carica papaya) (2n =2x = 18), an important fruit crop in Caricaceae, con- tains a pair of X/Y chromosomes that emerged only a few million years ago (MYA) (Yu et al. 2008; Wang et al. 2012). The young nature of papaya sex chromosomes was confirmed cytologically in which only a small portion (13%) of the X/Y Figure 1 Phylogenetic relationships in family Caricaceae. Branch lengths are proportional to time. Numbers on nodes represent age in million chromosomes is cytologically differentiated (Zhang et al. 2008). years. This chronogram is adapted from Carvalho and Renner (2012). Thus, papaya provides a model system to capture early molec- Species sampled in this study are in boldface type. ular and cytological events during sex chromosome evolution. The Vasconcellea/Jacaratia clade in Caricaceae is closely related or digoxigenin-11-dUTP (Roche Diagnostics, Indianapolis, IN), to papaya (Carvalho and Renner 2012) (Figure 1). We were using a standard nick translation reaction. Chromosomes were intrigued to know whether the dioecious Vasconcellea/Jacaratia counterstained with 49,6-diamidino-2-phenylindole (DAPI) in species contains sex chromosomes and whether such sex chro- VectaShield antifade solution (Vector Laboratories, Burlingame, mosomes are related to the papaya X/Y chromosome. We con- CA).TheFISHimageswereprocessedwithMetaImagingSe- ducted fluorescence in situ hybridization (FISH) of a set of ries 7.5 software. The final contrast of the images was processed bacterial artificial chromosome (BAC) clones, all of which using Adobe Photoshop CS3 software. Heterochromatin length were previously mapped to the papaya X/Y chromosomes, in was estimated based on DAPI staining pattern of the putative Y two Caricaceae species, Vasconcellea parviflora (2n =2x = 18) chromosome and expressed in percentage of the total chromo- and Jacaratia spinosa (2n =2x = 18). We demonstrate that some length. The Y-specific heterochromatic domain was esti- V. parviflora contains a pair of heteromorphic X/Y chromo- mated as the difference in heterochromatin content between somes that are homologous to the papaya X/Y chromosomes. X and Y chromosomes and was expressed as the percentage By contrast, the same pair of chromosomes in J. spinosa is of the total chromosome length. The position of a BAC clone homomorphic. These results reveal a dynamic nature of sex or other landmarks along the chromosome was estimated and chromosome evolution in the Caricaceae species. expressed as D/L 3 100, where D = distance of the landmark from the end of the short arm, and L = total chromosome Materials and Methods length. All measurements were made on digital photographs, using Meta Imaging Series 7.5 software. Materials fl Plants of V. parvi ora and J. spinosa were maintained at the Results Hawaii Agriculture Research Center as well as in the Texas fi fl AgriLife Research Center in Weslaco, Texas. Young male Identi cation of the X/Y chromosomes in V. parvi ora fl fi ower buds were collected and xed in 3:1 (100% ethanol: V. parviflora is a dioecious species with female and male ’ 2 ° glacial acetic acid) Carnoy s solution and kept at 20 until individuals. Both male and female flowers are morphologi- use. Twenty-nine papaya BAC clones were previously selected cally similar to those of papaya (Figure 2). Young flower fi and were either speci c to the papaya sex-determining region buds were collected from male V. parviflora plants to prepare fi (X or Y speci c) or to the papaya sex chromosomes (Zhang meiotic pachytene chromosomes. The pachytene karyotype of et al. 2008; Wai et al. 2012). A telomeric DNA probe, pAtT4 V. parviflora generally resembled the papaya karyotype (Zhang from Arabidopsis thaliana (Richards and Ausubel 1988), was et al. 2010), containing nine metacentric and submetacentric fl used to label the ends of V. parvi ora pachytene chromosomes. chromosomes of similar sizes (Figure 3C). Heterochromatin, which is brightly stained by DAPI, was visible in the pericentro- FISH meric regions of all nine pachytene chromosomes (Figure 3C). Chromosome
Load more

Recommended publications
  • Karyotype and Genome Size Determination of Jarilla Chocola, an Additional Sister Clade of Carica Papaya
    POJ 14(01):50-56 (2021) ISSN:1836-3644 doi: 10.21475/POJ.14.01.21.p2944 Karyotype and genome size determination of Jarilla chocola, an additional sister clade of Carica papaya Dessireé Patricia Zerpa-Catanho1, Tahira Jatt2, Ray Ming1* 1Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 2Department of Botany, Shah Abdul Latif University, Khaipur, Sindh, 66020, Pakistan *Corresponding author: [email protected] Abstract Jarilla chocola is an herbaceous plant species that belongs to the Jarilla genus and the Caricaceae family. No information on chromosome number or genome size has been reported for J. chocola that confirms the occurrence of dysploidy events and explore the existence of heteromorphic sex chromosomes. Therefore, the total number of chromosomes of this species was determined by karyotyping and counting the number of chromosomes observed, and the genome size of female and male plants was estimated separately by flow cytometry. Results showed that J. chocola has eight pairs of chromosomes (2n = 2x = 16), and its chromosomes are classified as metacentric for five pairs, submetacentric for two pairs and telocentric for one pair. The nuclear DNA content (1C- value) in picograms and diploid genome size was estimated separately from female and male plants using two species as the standards, Phaseolus vulgaris (1C = 0.60 pg) and Carica papaya (1C = 0.325 pg), to look for the possible existence of heteromorphic sex chromosomes. C. papaya proved to be a better standard for the determination of J. chocola DNA content and diploid genome size. No significant difference on the DNA content was observed between female (1C = 1.02 ± 0.003 pg) and male (1C = 1.02 ± 0.008 pg) plants.
    [Show full text]
  • An Overview of the Independent Histories of the Human Y Chromosome and the Human Mitochondrial Chromosome
    The Proceedings of the International Conference on Creationism Volume 8 Print Reference: Pages 133-151 Article 7 2018 An Overview of the Independent Histories of the Human Y Chromosome and the Human Mitochondrial chromosome Robert W. Carter Stephen Lee University of Idaho John C. Sanford Cornell University, Cornell University College of Agriculture and Life Sciences School of Integrative Plant Science,Follow this Plant and Biology additional Section works at: https://digitalcommons.cedarville.edu/icc_proceedings DigitalCommons@Cedarville provides a publication platform for fully open access journals, which means that all articles are available on the Internet to all users immediately upon publication. However, the opinions and sentiments expressed by the authors of articles published in our journals do not necessarily indicate the endorsement or reflect the views of DigitalCommons@Cedarville, the Centennial Library, or Cedarville University and its employees. The authors are solely responsible for the content of their work. Please address questions to [email protected]. Browse the contents of this volume of The Proceedings of the International Conference on Creationism. Recommended Citation Carter, R.W., S.S. Lee, and J.C. Sanford. An overview of the independent histories of the human Y- chromosome and the human mitochondrial chromosome. 2018. In Proceedings of the Eighth International Conference on Creationism, ed. J.H. Whitmore, pp. 133–151. Pittsburgh, Pennsylvania: Creation Science Fellowship. Carter, R.W., S.S. Lee, and J.C. Sanford. An overview of the independent histories of the human Y-chromosome and the human mitochondrial chromosome. 2018. In Proceedings of the Eighth International Conference on Creationism, ed. J.H.
    [Show full text]
  • A Comparative Survey of Genetic Diversity Among a Set of Caricaceae
    Sengupta et al. SpringerPlus 2013, 2:345 http://www.springerplus.com/content/2/1/345 a SpringerOpen Journal RESEARCH Open Access A comparative survey of genetic diversity among a set of Caricaceae accessions using microsatellite markers Samik Sengupta2, Basabdatta Das1, Manoj Prasad3, Pinaki Acharyya2 and Tapas Kumar Ghose1* Abstract A preliminary survey of genetic diversity among 34 commercially popular Carica papaya cultivars from India and abroad, 6 accessions of Vasconcellea species and 1 accession of Jacaratia spinosa, was done using 20 simple sequence repeat (SSR) markers. The SSR profiles were used to find out total number of alleles, null and rare alleles, Polymorphism Information Content (PIC) values and to calculate similarity matrix using Jaccard’s coefficient. The subsequent dendrogram was made by unweighted pair-group method of arithmetic average (UPGMA) and neighbor-joining method. Based on these parameters a comparison was made between the Indian papaya cultivars and the rest of the accessions. All the markers showed polymorphism and a total of 140 alleles were identified. The average number of alleles was 7 alleles/locus. Categorically the Vasconcellea and Jacaratia species had 54 alleles, the 7 non-Indian Carica papaya accessions had 70 and the 27 Indian accessions had 102 alleles. The average PIC value was 0.735 per marker. A total of 37 rare alleles were identified. Jacaratia spinosa had 17 rare alleles. Nineteen null alleles were detected among the Carica papaya accessions. A Carica papaya accession from South Africa, Hortus Gold had 5 null alleles. The genetic similarity among the accessions ranged from 7% to 67%. In the dendrogram, the Vasconcellea and Jacaratia spinosa accessions separated as a distinct cluster from the rest of the Carica papaya accessions.
    [Show full text]
  • Chec List What Survived from the PLANAFLORO Project
    Check List 10(1): 33–45, 2014 © 2014 Check List and Authors Chec List ISSN 1809-127X (available at www.checklist.org.br) Journal of species lists and distribution What survived from the PLANAFLORO Project: PECIES S Angiosperms of Rondônia State, Brazil OF 1* 2 ISTS L Samuel1 UniCarleialversity of Konstanz, and Narcísio Department C.of Biology, Bigio M842, PLZ 78457, Konstanz, Germany. [email protected] 2 Universidade Federal de Rondônia, Campus José Ribeiro Filho, BR 364, Km 9.5, CEP 76801-059. Porto Velho, RO, Brasil. * Corresponding author. E-mail: Abstract: The Rondônia Natural Resources Management Project (PLANAFLORO) was a strategic program developed in partnership between the Brazilian Government and The World Bank in 1992, with the purpose of stimulating the sustainable development and protection of the Amazon in the state of Rondônia. More than a decade after the PLANAFORO program concluded, the aim of the present work is to recover and share the information from the long-abandoned plant collections made during the project’s ecological-economic zoning phase. Most of the material analyzed was sterile, but the fertile voucher specimens recovered are listed here. The material examined represents 378 species in 234 genera and 76 families of angiosperms. Some 8 genera, 68 species, 3 subspecies and 1 variety are new records for Rondônia State. It is our intention that this information will stimulate future studies and contribute to a better understanding and more effective conservation of the plant diversity in the southwestern Amazon of Brazil. Introduction The PLANAFLORO Project funded botanical expeditions In early 1990, Brazilian Amazon was facing remarkably in different areas of the state to inventory arboreal plants high rates of forest conversion (Laurance et al.
    [Show full text]
  • Morphological Variation in the Flowers of Jacaratia
    Plant Biology ISSN 1435-8603 RESEARCH PAPER Morphological variation in the flowers of Jacaratia mexicana A. DC. (Caricaceae), a subdioecious tree A. Aguirre1, M. Vallejo-Marı´n2, E. M. Piedra-Malago´ n3, R. Cruz-Ortega4 & R. Dirzo5 1 Departamento de Biologı´a Evolutiva, Instituto de Ecologı´a A.C., Congregacio´ n El Haya, Xalapa, Veracruz, Me´ xico 2 Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada 3 Posgrado Instituto de Ecologı´a A.C., Congregacio´ n El Haya, Xalapa, Veracruz, Me´ xico 4 Departamento de Ecologı´a Funcional, Instituto de Ecologı´a, UNAM, Me´ xico 5 Department of Biological Sciences, Stanford University, Stanford, CA, USA Keywords ABSTRACT Caricaceae; dioecy; Jacaratia mexicana; Mexico; sexual variation. The Caricaceae is a small family of tropical trees and herbs in which most species are dioecious. In the present study, we extend our previous work on Correspondence dioecy in the Caricaceae, characterising the morphological variation in sex- A. Aguirre, Departamento de Biologı´a ual expression in flowers of the dioecious tree Jacaratia mexicana. We found Evolutiva, Instituto de Ecologı´a A.C., Km. 2.5 that, in J. mexicana, female plants produce only pistillate flowers, while Carretera Antigua a Coatepec 351, male plants are sexually variable and can bear three different types of flow- Congregacio´ n El Haya, Xalapa 91070, ers: staminate, pistillate and perfect. To characterise the distinct types of Veracruz, Me´ xico. flowers, we measured 26 morphological variables. Our results indicate that: E-mail: [email protected] (i) pistillate flowers from male trees carry healthy-looking ovules and are morphologically similar, although smaller than, pistillate flowers on female Editor plants; (ii) staminate flowers have a rudimentary, non-functional pistil and M.
    [Show full text]
  • Marker-Assisted Breeding for Papaya Ringspot Virus Resistance in Carica Papaya L
    Marker-Assisted Breeding for Papaya Ringspot Virus Resistance in Carica papaya L. Author O'Brien, Christopher Published 2010 Thesis Type Thesis (Masters) School Griffith School of Environment DOI https://doi.org/10.25904/1912/3639 Copyright Statement The author owns the copyright in this thesis, unless stated otherwise. Downloaded from http://hdl.handle.net/10072/365618 Griffith Research Online https://research-repository.griffith.edu.au Marker-Assisted Breeding for Papaya Ringspot Virus Resistance in Carica papaya L. Christopher O'Brien BAppliedSc (Environmental and Production Horticulture) University of Queensland Griffith School of Environment Science, Environment, Engineering and Technology Griffith University Submitted in fulfilment of the requirements of the degree of Master of Philosophy September 4, 2009 2 Table of Contents Page No. Abstract ……………………………………………………… 11 Statement of Originality ………………………………………........ 13 Acknowledgements …………………………………………. 15 Chapter 1 Literature review ………………………………....... 17 1.1 Overview of Carica papaya L. (papaya)………………… 19 1.1.1 Taxonomy ………………………………………………… . 19 1.1.2 Origin ………………………………………………….. 19 1.1.3 Botany …………………………………………………… 20 1.1.4 Importance …………………………………………………... 25 1.2 Overview of Vasconcellea species ……………………… 28 1.2.1 Taxonomy …………………………………………………… 28 1.2.2 Origin ……………………………………………………… 28 1.2.3 Botany ……………………………………………………… 31 1.2.4 Importance …………………………………………………… 31 1.2.5 Brief synopsis of Vasconcellea species …………………….. 33 1.3 Papaya ringspot virus (PRSV-P)…………………………. 42 1.3.1 Overview ………………………………………………………. 42 1.3.2 Distribution …………………………………………………… 43 1.3.3 Symptoms and effects ……………………………………….. .. 44 1.3.4 Transmission …………………………………………………. 45 1.3.5 Control ………………………………………………………. .. 46 1.4 Breeding ………………………………………………………. 47 1.4.1 Disease resistance …………………………………………….. 47 1.4.2 Biotechnology………………………………………………….. 50 1.4.3 Intergeneric hybridisation…………………………………….. 51 1.4.4 Genetic transformation………………………………………… 54 1.4.5 DNA analysis ……………………………………………….....
    [Show full text]
  • Chromosomal Localisation of a Y Specific Growth Gene(S) J Med Genet: First Published As 10.1136/Jmg.32.7.572 on 1 July 1995
    5727 JMed Genet 1995;32:572-575 Chromosomal localisation of a Y specific growth gene(s) J Med Genet: first published as 10.1136/jmg.32.7.572 on 1 July 1995. Downloaded from Tsutomu Ogata, Keiko Tomita, Akiko Hida, Nobutake Matsuo, Yutaka Nakahori, Yasuo Nakagome Abstract apparently large Yq terminal deletions are in- Although a Y specific growth gene(s) has variably sterile and occasionally have short been postulated in the Yqll region, the stature.24 However, since correlations between precise location has not been determined. genotype and stature have not been properly To localise the growth gene(s), we cor- examined, the precise location ofthe Y specific related genotype with stature in 13 Jap- growth gene(s) has not been determined. anese and four European non-mosaic In this paper, we attempt to localise the Y adult male patients with a partial Yq de- specific growth gene(s) on the basis of geno- letion. Fourteen patients preserving the type-phenotype correlations in patients with region between DYSll and DYS246 did Yq - chromosomes. not have short stature (11 Japanese, 165-180 cm; three Europeans, 165-173 cm) whereas the remaining three patients with Methods SELECTION OF PATIENTS the region deleted had short stature (two The patients analysed in the present study were Japanese, both 159 cm; one European, collected from a large series ofinfertile Japanese 157 cm). The results suggest that the region males ascertained from 1988 to 1993. The defined by DYS1I at interval 5C and by selection criteria used were: (1) measurement DYS246 at interval SD may be the critical of height between 20 and 50 years of age; region for the Y specific growth gene(s).
    [Show full text]
  • Final Report
    Final Report New Genetic Targets to Improve Quality in Papaya Project leader: Rebecca Ford Delivery partner: Griffith University Project code: PP15000 Hort Innovation – Final Report Project: New Genetic Targets to Improve Quality in Papaya – PP15000 Disclaimer: Horticulture Innovation Australia Limited (Hort Innovation) makes no representations and expressly disclaims all warranties (to the extent permitted by law) about the accuracy, completeness, or currency of information in this Final Report. Users of this Final Report should take independent action to confirm any information in this Final Report before relying on that information in any way. Reliance on any information provided by Hort Innovation is entirely at your own risk. Hort Innovation is not responsible for, and will not be liable for, any loss, damage, claim, expense, cost (including legal costs) or other liability arising in any way (including from Hort Innovation or any other person’s negligence or otherwise) from your use or non‐use of the Final Report or from reliance on information contained in the Final Report or that Hort Innovation provides to you by any other means. Funding statement: This project has been funded by Hort Innovation, using the papaya research and development levy, co‐investment from Griffith University and contributions from the Australian Government. Hort Innovation is the grower‐owned, not‐for‐profit research and development corporation for Australian horticulture. Publishing details: ISBN 978 0 7341 4403 4 Published and distributed by: Hort Innovation Level 8 1 Chifley Square Sydney NSW 2000 Telephone: (02) 8295 2300 www.horticulture.com.au © Copyright 2018 Horticulture Innovation Australia Limited Contents Summary ......................................................................................................................................
    [Show full text]
  • Jacaratia Mexicana Seedlings Inoculated with Arbuscular Mycorrhizal Fungi in a Tropical Dry Forest
    Madera y Bosques vol. 21, núm. 3: 161-167 Otoño 2015 Survival and growth of Jacaratia mexicana seedlings inoculated with arbuscular mycorrhizal fungi in a tropical dry forest Supervivencia y crecimiento de plántulas de Jacaratia mexicana inoculadas con hongos micorrícico arbusculares dentro de un bosque tropical seco Ramón Zulueta-Rodríguez1, Luis G. Hernandez-Montiel2*, Bernardo Murillo-Amador2, Miguel V. Córdoba-Matson2 y Liliana Lara1 and Isabel Alemán Chávez1 1 Facultad de Ciencias Agrícolas. Universidad Veracru- 2 Centro de Investigaciones Biológicas del Noroeste. * Corresponding author: [email protected] zana. Xalapa, Veracruz, México. La Paz, Baja California Sur, México. ABSTRACT Jacaratia mexicana is not only an endemic and typical tropical dry forest tree of Mexico, it is considered as a direct ancestor of the pa- payo (Carica papaya). Locally it is mainly used in traditional medicine, for human food or for feeding backyard animals (forage plant), but its use value is very restricted or even unknown. Nevertheless, various abiotic and anthropogenic pressures in its Mexican habitat are causing populations of this tree to decline alarmingly. Arbuscular mycorrhizal fungi (AMF) are microorganisms that have an important role for the regeneration of tree species by increasing their ability to absorb water and nutrients. The aim of this study was to determine the effect of AMF on growth and survival of seedlings of J. mexicana transplanted within a fragmented area of the remaining dry forest located in the central portion of the state of Veracruz. We measured height, stem diameter, number of leaves, percent seedling survival and mycorrhizal colonization. Results showed increases in all growth-related variables when seedlings were inoculated with AMF.
    [Show full text]
  • Y Chromosome in the Male Drosophila'
    THE EFFECT OF TEMPERATURE ON MEIOTIC LOSS OF THE Y CHROMOSOME IN THE MALE DROSOPHILA' S. ZIMMERING Department of Biology, Brown University, Prouidence, Rhode Island Received September 19, 1962 GERSHENSON (1933) and SANDLERand BRAVER(1954) have clearly shown that following nondisjunction of X and Y in the Drosophila mehnogaster male, the frequency of recovery of XY sperm is markedly lower than that of nullo-X-nullo-Y sperm. Their suggestion to account for this discrepancy was to suppose that a chromosome which fails to pair with its homologue may be lost at meiosis. Such loss was found to be most pronounced in cases in which the X chromosome was deficient for a large portion of the basal heterochromatin ordinarily involved in pairing with the Y chromosome. Preliminary data ( ZIMMERING1962 and unpublished) have suggested that (1) from situations in which the homology between X and Y is greatly reduced, the rate of chromosome loss at meiosis can be appreciably decreased by tempera- ture treatment, and furthermore, that (2) such a decrease in the rate of loss need not necessarily involve an increase in the frequency of X-Y synapsis prior to anaphase I separation. A detailed account of these and subsequent experi- ments is presented below. MATERIALS AND METHODS Males possessing a modified X chromosome, Zns(1)y sc4-sc8, and the sc8.Y of MULLER( 1948) were employed in the initial temperature experiments. Zn(1)y scb, a long inversion of the X chromosome marked distally with the mutant y (yellow body), leaves most of the basal heterochromatin including bb+ and Block A at the proximal region, while Zn(l)sc8, also a long inversion of the X chromosome, transposes most of the basal heterochromatin including bb+ and Block A distally.
    [Show full text]
  • Molecular Evolution of a Y Chromosome to Autosome Gene Duplication in Drosophila Research Article
    Molecular Evolution of a Y Chromosome to Autosome Gene Duplication in Drosophila Kelly A. Dyer,*,1 Brooke E. White,1 Michael J. Bray,1 Daniel G. Pique´,1 and Andrea J. Betancourt* ,2 1Department of Genetics, University of Georgia 2Institute of Evolutionary Biology, University of Edinburgh, Ashworth Labs, Edinburgh, United Kingdom Present address: Institute for Population Genetics, University of Veterinary Medicine Vienna, Vienna 1210, Austria *Corresponding author: [email protected], [email protected]. Associate editor: Jody Hey Abstract In contrast to the rest of the genome, the Y chromosome is restricted to males and lacks recombination. As a result, Research article Y chromosomes are unable to respond efficiently to selection, and newly formed Y chromosomes degenerate until few genes remain. The rapid loss of genes from newly formed Y chromosomes has been well studied, but gene loss from highly degenerate Y chromosomes has only recently received attention. Here, we identify and characterize a Y to autosome duplication of the male fertility gene kl-5 that occurred during the evolution of the testacea group species of Drosophila. The duplication was likely DNA based, as other Y-linked genes remain on the Y chromosome, the locations of introns are conserved, and expression analyses suggest that regulatory elements remain linked. Genetic mapping reveals that the autosomal copy of kl-5 resides on the dot chromosome, a tiny autosome with strongly suppressed recombination. Molecular evolutionary analyses show that autosomal copies of kl-5 have reduced polymorphism and little recombination. Importantly, the rate of protein evolution of kl-5 has increased significantly in lineages where it is on the dot versus Y linked.
    [Show full text]
  • Centromeric Satellite Dnas: Hidden Sequence Variation in the Human Population
    G C A T T A C G G C A T genes Review Centromeric Satellite DNAs: Hidden Sequence Variation in the Human Population Karen H. Miga UC Santa Cruz Genomics Institute, University of California, Santa Cruz, California, CA 95064, USA; [email protected]; Tel.: +1-831-459-5232 Received: 2 April 2019; Accepted: 3 May 2019; Published: 8 May 2019 Abstract: The central goal of medical genomics is to understand the inherited basis of sequence variation that underlies human physiology, evolution, and disease. Functional association studies currently ignore millions of bases that span each centromeric region and acrocentric short arm. These regions are enriched in long arrays of tandem repeats, or satellite DNAs, that are known to vary extensively in copy number and repeat structure in the human population. Satellite sequence variation in the human genome is often so large that it is detected cytogenetically, yet due to the lack of a reference assembly and informatics tools to measure this variability, contemporary high-resolution disease association studies are unable to detect causal variants in these regions. Nevertheless, recently uncovered associations between satellite DNA variation and human disease support that these regions present a substantial and biologically important fraction of human sequence variation. Therefore, there is a pressing and unmet need to detect and incorporate this uncharacterized sequence variation into broad studies of human evolution and medical genomics. Here I discuss the current knowledge of satellite DNA variation in the human genome, focusing on centromeric satellites and their potential implications for disease. Keywords: satellite DNA; centromere; sequence variation; structural variation; repeat; alpha satellite; human satellites; genome assembly 1.
    [Show full text]