Search results for "chromosome"
showing 10 items of 1175 documents
Multiple-chromosome sex systems in the darkling beetles Blaps gigas and Blaps gibba (Coleoptera, Tenebrionidae)
1996
We have studied mitotic and meiotic chromosomes in the males of two species of Blaps: B. gigas and B. gibba. Karyological characteristics such as the occurrence of a multivalent configuration at diakinesis and two types of metaphase-II spreads support the notion that multiple-chromosome sex systems involving five chromosomes in B. gigas and eight chromosomes in B. gibba have developed in these species. Results obtained by means of silver staining and C-banding techniques suggest that the complex sex systems occurring in B. gigas and B. gibba may have originated from exchanges of terminal ribosomal genes among the Y chromosome and some autosomes.
B1 Was the Ancestor B Chromosome Variant in the Western Mediterranean Area in the Grasshopper Eyprepocnemis plorans.
2014
We analyzed the distribution of 2 repetitive DNAs, i.e. ribosomal DNA (rDNA) and a satellite DNA (satDNA), on the B chromosomes found in 17 natural populations of the grasshopper Eyprepocnemis plorans plorans sampled around the western Mediterranean region, including the Iberian Peninsula, Balearic Islands, Sicily, and Tunisia. Based on the amount of these repetitive DNAs, 4 types of B variants were found: B 1 , showing an equal or higher amount of rDNA than satDNA, and 3 other variants, B 2 , B 24 and B 5 , bearing a higher amount of satDNA than rDNA. The variants B 1 and B 2 varied in size among populations: B 1 was about half the size of the X chromosome in Balearic Islands, but two-thir…
Chromosome numbers in plant taxa endemic to the Balearic Islands
2005
Mitotic chromosome numbers are reported from 20 vascular plant taxa that are endemic to the Balearic Islands and poorly known cytogenetically. The chromosome numbers of Arenaria grandiflora L. ssp. glabrescens (Willk.) G. Lopez & Nieto Feliner (2n = 44), Dianthus rupicola Viv. ssp. bocchoriana L. Llorens & Gradaille (2n = 30), Solenopsis minuta (L.) C. Presl. ssp. balearica (E. Wimm.) Meikle (2n = 28), Romulea asumptionis Font Quer & Garcias Font (2n = 56), Scutellaria balearica Barcelo (2n = 22) and Galium balearicum Briq. (2n = 22) have been determined for the first time. A new chromosome number was found in two populations of Helictotrichon crassifolium (Font Quer) Holub (2n = c. 98) sug…
A new annual species of Bellium (Asteraceae) from the Balearic Islands
2007
A new species, Bellium artrutxensis (Asteraceae: Astereae), is described from the therophytic pastures of southern Minorca (Balearic Islands). The analysis of nuclear ribosomal internal transcribed spacer (ITS) sequences showed that the new taxon was closely related to Bellium bellidioides , but differed with regard to the annual lifespan, the absence of epigeal stolons, and the presence of a patent eglandular indumentum on the leaves. The new taxon shows morphological features that are well suited for the colonization of dry environments with a marked summer drought, and may be of adaptive significance. The new species is diploid (2 n = 18) and shows up to two accessory chromosomes in root…
Taxonomy of the genusBrimeura (Hyacinthaceae)
2001
A taxonomic reevaluation of two little-knownBrimeura taxa,B. fontqueri (Pau)Speta andB. duvigneaudii (L. Llorens)Rossello et al., has been made.Brimeura fontqueri, described from the Iberian peninsula, has been put into synonymy ofB. amethystina (L.)Salisb., since it could not be distinguished on morphological, anatomical or cytogenetic grounds.Brimeura duvigneaudii, from the Balearic Islands, is closely related toB. amethystina and has 2n=28 chromosomes. It differs from the latter by its naked bulbs lacking dark cataphylls, and its narrower leaves and whitish corollas. Accessory chromosomes are reported for the first time in the genus. Karyological instability (with chromosome numbers rang…
Global variation in the genetic and biochemical basis of diamondback moth resistance to Bacillus thuringiensis
1997
Insecticidal proteins from the soil bacterium Bacillus thuringiensis (Bt) are becoming a cornerstone of ecologically sound pest management. However, if pests quickly adapt, the benefits of environmentally benign Bt toxins in sprays and genetically engineered crops will be short-lived. The diamondback moth ( Plutella xylostella ) is the first insect to evolve resistance to Bt in open-field populations. Here we report that populations from Hawaii and Pennsylvania share a genetic locus at which a recessive mutation associated with reduced toxin binding confers extremely high resistance to four Bt toxins. In contrast, resistance in a population from the Philippines shows multilocus control, a …
Fluorescence In Situ Hybridization (FISH) on Formalin-Fixed Paraffin-Embedded (FFPE) Tissue Sections
2011
Fluorescence In Situ Hybridization (FISH) is a powerful technique for localizing specific DNA targets directly in the fixed tissue or cells. Bacterial artificial chromosome (BAC) as well as commercial probes, which could be supplied ready for use or concentrated and must be diluted following the manufacturers instructions, can be used. The technique requires 2 days, as an overnight incubation of the FISH probes is needed for optimal hybridization. The critical steps include deparaffinization of tissue sections, optimal pretreatment (target retrieval and protein digestion), and probe hybridization. In this chapter, the described FISH protocol provides a methodology for analyzing the cytogene…
Chromosome numbers in Hieracium and Pilosella species (Asteraceae) from the Iberian Peninsula and the Balearic Islands
2007
Mitotic chromosome numbers are reported from 16 Hieracium and two Pilosella species from the Iberian Peninsula and the Balearic Islands that are little known cytogenetically. The chromosome numbers of Hieracium aragonense Scheele (2 n = 27, 36), H. compositum Lapeyr. (2 n = 27), H. murcandidum G. Mateo (2 n = 27), H. spathulatum Scheele (2 n = 27), H. segurae Mateo (2 n = 27), H. teruelanum Mateo (2 n = 27), H. valentinum Pau (2 n = 27), Pilosella pseudovahlii (De Retz) Mateo (2 n = 18), and P. tardans (Peter) Sojak (2 n = 36) were determined for the first time. New cytotypes were detected in H. cordifolium Lapeyr. (2 n = 27) and H. loscosianum Scheele (2 n = 36). The karyo- type of the stu…
Karyology of Limonium (Plumbaginaceae) species from the Balearic Islands and the western Iberian Peninsula
2007
Somatic chromosome numbers, conventional karyotype features and idiograms are reported for 27 Limonium species inhabiting the Western Mediterranean basin (Iberian Peninsula and the Balearic Islands). The chromosome numbers of Limonium barceloi (2n = 36), L. ejulabilis (2n = 24), L. inexpectans (2n = 26), L. interjectum (2n = 24), and L. scopulorum (2n = 25) were determined for the first time. In addition, new aneuploid and/or polyploid cytotypes are reported in L. alcudianum (2n = 26), L. bonafei (2n = 26), L. camposanum (2n = 26), L. companyonis (2n = 26), L. dufourii (2n = 26), L. geronense (2n = 36), L. marisolii (2n = 54), L. migjornense (2n = 50), and L. pseudodictyocladon (2n = 16). A…
<i>Limonium carvalhoi (Plumbaginaceae)</i>, a new endemic species from the Balearic Islands
1998
ROSSELLO, J.A., L. SAEZ & A.C. CARVALHO (1998). Limonium carvalhoi (Plumbaginaceae), a new endemic species from the Balearic Islands. Anales Jard. Bot. Madrid 56(1): 23-31. Limonium carvalhoi Rossello & L. Saez is described from a single salt marsh locality in southwest Majorca. Morphologically, L. carvalhoi is ciose to L. inexpectans, L. migjornense and L. magallufianum , all Balearic endemics. The new species has an apomictic breeding system and shows a single pollen/stigma combination (B/papillate type). Chromosome number ranges from 2n = 24 to 2n = 26. Based on the occurrence of a long metacentric chromosome in all cells examined, it is suggested that the original chromosome complement …