Cytotaxonomy and phylogeny in certain species ofTaxodiaceae

Various species ofTaxodiaceae were selected for chromosome studies to indicate cytotaxonomic and phylogenetic relationships. Point dispersal patterns of diagrammatic presentations of the species' karyotypes, rather than marker chromosomes, were found to be the most significant cytotaxonomic characteristic in indicating phylogenetic relationships. Karyotypic evolution inTaxodiaceae appears to occur by unequal reciprocal translocations followed by pericentric and paracentric inversions. Cytotaxonomic relationships among species generally correspond to the phylogenetic relationships withinTaxodiaceae indicated by classical taxonomic classification. Presence and types of marker chromosomes may have the potential to indicate relationships between different coniferous families.     

A cytotaxonomic study of some Australian species of Drosera L. (Droseraceae)

KONDO, K. & LAVARACK, P. S., 1984. A cytotaxonomic study of some Australian species of Drosera L. (Droseraceae). Karyomorphological comparisons of 15 species of Australian Drosera are presented along with 11 new chromosome counts. In Australia the genus forms an extensive aneuploid series. The species which have chromosome numbers from n =10 to n = 19 show large chromosomes, while those which have chromosome numbers more than 20 show small chromosomes. Drosera paleacca shows the lowest chromosome number in the genus, 2 n = 10, with 10 large chromosomes, indicating a new basic number, x = 5. The non-staining gap between the chromatids of each chromosome is rather wide and their centromeric region is not seen throughout prophase, prometaphase, and metaphase. The C-banding and silver-staining analyses in Drosera petiolaris chromosomes suggest that Drosera chromosomes could have diffuse centromeres and simplified C-segments. Some taxonomic implications are considered, notably the possible removal of Drosera banksii from Drosera section Ergaleium to Drosera section Lasiocephala and the reduction to synonymy of Drosera section Prolifera .     

Alteration of steroid hormone sensitivity during the cultivation of human mammary carcinoma cells

Summary During early cultivation steps of the newly derived and karyotyped human mammary carcinoma line EFM-19, the cells developed faster growth rates and became increasingly less responsive to the presence of serum in the culture medium. No drastic alterations of the morphology and of the karyotype were observed, and carcinoembryogenic antigen remained expressed during the course of the cultivation. In experimental incubations at various time intervals after the explantation, the cell proliferation was analyzed for dose-dependent effects of estradiol, cortisol, progesterone, and testosterone. After 16 wk of cultivation of the stock culture in the presence of estradiol, the cells had acquired a distinct sensitivity to estradiol resulting in permanent growth enhancement. The withdrawal of cortisol from the medium of the stock culture subsequently provoked the loss of the initially noted stimulation of the proliferation by cortisol. The stimulatory effect of progesterone on the proliferation was reversed to inhibition when the stock culture was deprived of cortisol in the growth medium. The results indicate that the choice of steroid hormones in the stock culture medium was determining the quality of the cellular growth responses. This work was supported by the Deutsche Forschungsgemeinschaft, SFB34.     

Chromosome cytology and karyotype change inGalaxia (Iridaceae)

Basic chromosome number inGalaxia is believed to be x = 9, and this number, or multiples, occurs in all species of subgenusGalaxia. In subgenusEurystigma, G. barnardii has n = 8,G. versicolor n = 8 and 7,G. citrina n = 8, 7 and 17 whileG. variabilis has n = 7 exclusively. Karyotypes in forms ofG. versicolor with n = 7 and inG. variabilis are quite different and clearly originated independently. Karyotypic features provide evidence for the hypothesis that changes in chromosome number were accomplished through chromosome fusion either by classical Robertsonian translocation, or unequal reciprocal translocation.     

Inter-Strain Variability of Insertion/Deletion Events in the Encephalitozoon cuniculi Genome: A Comparative KARD-PFGE Analysis

ABSTRACT. We applied a two-dimensional pulsed-field gel electrophoresis procedure to the genomes of two karyotype variants assigned to two different strains of the microsporidian Encephalitozoon cuniculi , termed D (strain III) and F (strain II). Data obtained for Bss HII and Mlul restriction fragment length polymorphisms in each chromosome are compiled and compared to the reference strain I variant A. Six Insertion/Deletion (InDels) are found in subterminal position, some of these being characteristic of either D or F. Like in strain I, the terminal fragments extending between each telomere and rDNA locus are conserved in length for each chromosome. They are however smaller than in reference variant. This size reduction is estimated to be 2.5 kbp for the strain III isolate and 3.5 kbp for the strain II isolate. We hypothesize that for the three E. cuniculi strains, all chromosome extremities are prone to a constant process of sequence homogenization through mitolic recombination between conserved regions.     

First report of chromosomes of the parasitoid wasp Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae: Telenominae)

Here we present the first data on the chromosome complement of Trissolcus basalis gathered in conjunction with the ongoing whole genome sequencing efforts for this species. The cytogenetic investigation revealed a diploid karyotype with 20 chromosomes, comprising one pair of large metacentrics and nine pairs of acrocentrics that gradually decrease in length.     

Chromosomal diversification of diploid number,heterochromatin and rDNAs in two species of Phanaeus beetles (Scarabaeidae,Scarabaeinae)

The genus Phanaeus is included in the tribe Phanaeini, one of the most diverse tribes within the subfamily Scarabaeinae in terms of chromosomal characteristics. However, so far the species of this genus were not studied with differential cytogenetic techniques, limiting any inference of the probable mechanisms responsible for this diversity. In this work, several techniques were applied with the aim of cytogenetically characterizing two Phanaeus species. The karyotype found for Phanaeus (Notiophanaeus) chalcomelas was 2n = 12, neo-XY, and that of P. (N.) splendidulus was 2n = 20, Xy_p, considered primitive for the family Scarabaeidae. The chromosomes of both species showed a high amount of constitutive heterochromatin (CH), with blocks rich in base pairs GC (CMA₃⁺). Moreover, in P. (N.) chalcomelas the marks revealed by C-banding and fluorochrome staining were different in size, showing CH variability. Sites of 18S ribosomal DNA (rDNA) were identified in one autosomal pair of P. (N.) chalcomelas and in five autosomal pairs of P. (N.) splendidulus. On the other hand, only one autosomal pair exhibited 5S rDNA sequences in these species. The results suggest that the karyotype differentiation of the Phanaeus species studied here involved pericentric inversions and centric fusions, as well as mechanisms related to amplification and dispersion of CH and rDNA sequences.     

The cytology of the genus Alopecurus (Gramineae)

For a study of hybridization in Alopecurus , chromosome numbers, karyotypes, meiotic chromosome behaviour and breeding systems have been investigated in six species. In addition to confirming many previous chromosome numbers, new triploid and tetraploid counts have been found in A. bulbosus , which have not previously been reported. The karyotypes of all species have a very similar morphology but there are differences in chromosome size which can be related to differences in nuclear DNA content. At meiosis the diploid species form bivalents, but one population of A. aequalis contains plants that regularly form a single quadrivalent which would appear to be interchange heterozygotes. The meiotic behaviour of the tetraploids suggests that A. pratensis is an allotetraploid and A. geniculatus an autotetraploid. All species appear to be allogamous, although some, such as A. myosuroides are obligate outbreeders resulting from the presence of a self-incompatibility system, outbreeding is promoted in others by differences in the time of maturity of stigmas and anthers.     

Cell lines from the melolonthine scarabAntitrogus parvulus

Summary Continuously replicating cell lines have been established from embryonic tissue and circulating hemolymph cells of the melolonthineAntitrogus parvulus Britton. Isozyme analyses demonstrated that cell lines from both tissue sources expressed essentially the same isoforms of enzymes asA. parvulus larvae and thus confirmed the species of their origin. Karyotype analyses showed that cells from both tissue sources had accumulated changes in chromosome number and morphology during culture. Availability of melolonthine-derived cells should assistin vitro studies of the pathogens of this important group of beetles.