Chapter^>16: Chromosome Evolution, Divergent Meiotic Pathways, and Speciation in the Family Rivulidae

Annual Fishes ◽  
2015 ◽  
pp. 298-311 ◽  
Keyword(s):  
Chromosome Evolution ◽  
The Family

Comparative genomics: tracking chromosome evolution in the family Ursidae using reciprocal chromosome painting

1998 ◽  
Vol 83 (3-4) ◽  
pp. 182-192 ◽  
Author(s):  
W.G. Nash ◽  
J. Wienberg ◽  
M.A. Ferguson-Smith ◽  
J.C. Menninger ◽  
S.J. O’Brien
Keyword(s):  
Comparative Genomics ◽  
Chromosome Painting ◽  
Chromosome Evolution ◽  
Reciprocal Chromosome Painting ◽  
The Family

scholarly journals Monocentric chromosomes in Juncus (Juncaceae) and implications for the chromosome evolution of the family

2019 ◽  
Vol 191 (4) ◽  
pp. 475-483 ◽  
Author(s):  
Marcelo Guerra ◽  
Tiago Ribeiro ◽  
Leonardo P Felix
Keyword(s):  
In Situ Hybridization ◽  
Fluorescent In Situ Hybridization ◽  
Chromosome Evolution ◽  
Holocentric Chromosomes ◽  
Mitotic Chromosomes ◽  
Restricted Area ◽  
Rdna Sites ◽  
The Family ◽  
Meiotic Analyses

Abstract Holocentric chromosomes are rare among angiosperms, but have been suggested to be shared by all or most of the species of Cyperaceae and Juncaceae. However, no clear demonstration of the centromere type in Juncus, the largest genus of Juncaceae, has so far been published. Thus, we conducted a detailed chromosomal investigation of four Juncus spp. aiming to identify their centromere type. Mitotic chromosomes were analysed using the fluorochromes CMA and DAPI, fluorescent in situ hybridization (FISH) with rDNA probes and immunodetection of histones H3 phosphorylated at serine 10 (H3-S10ph) and H2A phosphorylated at threonine 133 (H2A-T133ph). DAPI-stained chromosomes of all species displayed typical primary constrictions, which were not related to AT-poor CMA+ heterochromatin or rDNA sites (usually negatively stained with DAPI). Immunodetection with H3-S10ph and H2A-T133ph revealed hyperphosphorylation of pericentromeric and centromeric regions, respectively, in a restricted area, as observed in monocentric chromosomes. Meiotic analyses in J. microcephalus showed no indication of inverted meiosis, commonly found in plants with holocentric chromosomes. Since the species investigated here belong to four different sections of Juncus and all of them display typical monocentric chromosomes, it seems that this kind of centromere is common in the genus and may represent the standard centromere organization for Juncus. If Juncus has monocentric chromosomes, there is no reason to hypothesize that other genera of Juncaceae for which centromeres have not been carefully investigated have holocentric chromosomes.

scholarly journals Evolution of sex chromosomes is prior to speciation in the dioecious Phoenix species

2015 ◽  
Author(s):  
Emira Cherif ◽  
Salwa Zehdi ◽  
Amandine Crabos ◽  
Karina Castillo ◽  
Nathalie Chabrillange ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Applied Research ◽  
Date Palm ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Driving Forces ◽  
Molecular Processes ◽  
Dioecious Species ◽  
The Family ◽  
Suppressed Recombination

Understanding the driving forces and molecular processes underlying dioecy and sex chromosome evolution, leading from hermaphroditism to the occurrence of male and female individuals, is of considerable interest in fundamental and applied research. The genus Phoenix, belonging to the family Arecaceae, consists of only dioecious species. Phylogenetic data suggests that the genus Phoenix diverged from a hermaphroditic ancestor shared with its closest relatives. Here we investigated the evolution of suppressed recombination within the genus Phoenix as a whole by extending the analysis of P. dactylifera sex-related loci to eight other species within the genus. We also performed a phylogenetic analysis of a date palm sex-linked PdMYB1 gene in these species. We found that X and Y sex-linked alleles clustered in a species-independent fashion. Our data show that sex chromosomes evolved before the diversification of the extant dioecious species. Furthermore, the distribution of Y haplotypes revealed two male ancestral paternal lineages which may have emerged prior to speciation.

scholarly journals Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ivalú M. Ávila Herrera ◽  
Jiří Král ◽  
Markéta Pastuchová ◽  
Martin Forman ◽  
Jana Musilová ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Karyotype Evolution ◽  
Sex Chromosome ◽  
Genomic Analysis ◽  
Nucleolus Organizer ◽  
Evolutionary Pattern ◽  
Holokinetic Chromosomes ◽  
Nucleolus Organizer Regions ◽  
The Family

Abstract Background Despite progress in genomic analysis of spiders, their chromosome evolution is not satisfactorily understood. Most information on spider chromosomes concerns the most diversified clade, entelegyne araneomorphs. Other clades are far less studied. Our study focused on haplogyne araneomorphs, which are remarkable for their unusual sex chromosome systems and for the co-evolution of sex chromosomes and nucleolus organizer regions (NORs); some haplogynes exhibit holokinetic chromosomes. To trace the karyotype evolution of haplogynes on the family level, we analysed the number and morphology of chromosomes, sex chromosomes, NORs, and meiosis in pholcids, which are among the most diverse haplogyne families. The evolution of spider NORs is largely unknown. Results Our study is based on an extensive set of species representing all major pholcid clades. Pholcids exhibit a low 2n and predominance of biarmed chromosomes, which are typical haplogyne features. Sex chromosomes and NOR patterns of pholcids are diversified. We revealed six sex chromosome systems in pholcids (X0, XY, X1X20, X1X2X30, X1X2Y, and X1X2X3X4Y). The number of NOR loci ranges from one to nine. In some clades, NORs are also found on sex chromosomes. Conclusions The evolution of cytogenetic characters was largely derived from character mapping on a recently published molecular phylogeny of the family. Based on an extensive set of species and mapping of their characters, numerous conclusions regarding the karyotype evolution of pholcids and spiders can be drawn. Our results suggest frequent autosome–autosome and autosome–sex chromosome rearrangements during pholcid evolution. Such events have previously been attributed to the reproductive isolation of species. The peculiar X1X2Y system is probably ancestral for haplogynes. Chromosomes of the X1X2Y system differ considerably in their pattern of evolution. In some pholcid clades, the X1X2Y system has transformed into the X1X20 or XY systems, and subsequently into the X0 system. The X1X2X30 system of Smeringopus pallidus probably arose from the X1X20 system by an X chromosome fission. The X1X2X3X4Y system of Kambiwa probably evolved from the X1X2Y system by integration of a chromosome pair. Nucleolus organizer regions have frequently expanded on sex chromosomes, most probably by ectopic recombination. Our data suggest the involvement of sex chromosome-linked NORs in achiasmatic pairing.

Triassic sponges (Sphinctozoa) from Hells Canyon, Oregon

1988 ◽  
Vol 62 (03) ◽  
pp. 419-423 ◽  
Author(s):  
Baba Senowbari-Daryan ◽  
George D. Stanley
Keyword(s):  
Endemic Species ◽  
Upper Triassic ◽  
Island Arc ◽  
Tropical Island ◽  
The Family ◽  
Wallowa Terrane ◽  
Unique Condition ◽  
Hells Canyon

Two Upper Triassic sphinctozoan sponges of the family Sebargasiidae were recovered from silicified residues collected in Hells Canyon, Oregon. These sponges areAmblysiphonellacf.A. steinmanni(Haas), known from the Tethys region, andColospongia whalenin. sp., an endemic species. The latter sponge was placed in the superfamily Porata by Seilacher (1962). The presence of well-preserved cribrate plates in this sponge, in addition to pores of the chamber walls, is a unique condition never before reported in any porate sphinctozoans. Aporate counterparts known primarily from the Triassic Alps have similar cribrate plates but lack the pores in the chamber walls. The sponges from Hells Canyon are associated with abundant bivalves and corals of marked Tethyan affinities and come from a displaced terrane known as the Wallowa Terrane. It was a tropical island arc, suspected to have paleogeographic relationships with Wrangellia; however, these sponges have not yet been found in any other Cordilleran terrane.

Electron Microscopy of Mycoplasma Pneumoniae

1971 ◽  
Vol 29 ◽  
pp. 258-259 ◽  
Author(s):  
E. S. Boatman ◽  
G. E. Kenny
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Growth Phase ◽  
Hela Cells ◽  
Sulfonic Acid ◽  
Gamma Globulin ◽  
Horse Serum ◽  
Morphological Aspects ◽  
The Family

Information concerning the morphology and replication of organism of the family Mycoplasmataceae remains, despite over 70 years of study, highly controversial. Due to their small size observations by light microscopy have not been rewarding. Furthermore, not only are these organisms extremely pleomorphic but their morphology also changes according to growth phase. This study deals with the morphological aspects of M. pneumoniae strain 3546 in relation to growth, interaction with HeLa cells and possible mechanisms of replication.The organisms were grown aerobically at 37°C in a soy peptone yeast dialysate medium supplemented with 12% gamma-globulin free horse serum. The medium was buffered at pH 7.3 with TES [N-tris (hyroxymethyl) methyl-2-aminoethane sulfonic acid] at 10mM concentration. The inoculum, an actively growing culture, was filtered through a 0.5 μm polycarbonate “nuclepore” filter to prevent transfer of all but the smallest aggregates. Growth was assessed at specific periods by colony counts and 800 ml samples of organisms were fixed in situ with 2.5% glutaraldehyde for 3 hrs. at 4°C. Washed cells for sectioning were post-fixed in 0.8% OSO4 in veronal-acetate buffer pH 6.1 for 1 hr. at 21°C. HeLa cells were infected with a filtered inoculum of M. pneumoniae and incubated for 9 days in Leighton tubes with coverslips. The cells were then removed and processed for electron microscopy.

Exposure of protein VP7 on the surface of bluetongue virus

1990 ◽  
Vol 48 (3) ◽  
pp. 600-601
Author(s):  
A.D. Hyatt
Keyword(s):  
Bluetongue Virus ◽  
Structural Proteins ◽  
Major Constituent ◽  
Outer Coat ◽  
Virus Particles ◽  
Antibody Recognition ◽  
The Core ◽  
The Family ◽  
Electron Microscopical ◽  
Physical Accessibility

Bluetongue virus (BTV) is the type species os the genus orbivirus in the family Reoviridae. The virus has a fibrillar outer coat containing two major structural proteins VP2 and VP5 which surround an icosahedral core. The core contains two major proteins VP3 and VP7 and three minor proteins VP1, VP4 and VP6. Recent evidence has indicated that the core comprises a neucleoprotein center which is surrounded by two protein layers; VP7, a major constituent of capsomeres comprises the outer and VP3 the inner layer of the core . Antibodies to VP7 are currently used in enzyme-linked immunosorbant assays and immuno-electron microscopical (JEM) tests for the detection of BTV. The tests involve the antibody recognition of VP7 on virus particles. In an attempt to understand how complete viruses can interact with antibodies to VP7 various antibody types and methodologies were utilized to determine the physical accessibility of the core to the external environment.

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