A cytogenetic study on three Chilean species of Chrysomelinae (Coleoptera, Chrysomelidae)

Three species of Chilean leaf beetles were chromosomally analyzed. The endemic Araucanomela wellingtonensis displays a male meioformula of 13 + Xyp with 2n = 28 chromosomes and an asymmetric karyotype with two large autosome pairs and 12 medium/small pairs of autosomes and sex-chromosomes, a diploid number which had not been found among the other species of the subtribe Paropsina sensu lato studied to date. Strichosa eburata presents a meioformula of 11 + Xyp, 2n = 24 chromosomes, as occurs in many species of chrysomelines belonging to different subtribes. Furthermore, Phaedon cyanopterum has a 16 + Xyp meioformula, that is 2n = 34 chromosomes, of small size mostly, also in agreement with the karyological findings obtained in all the other congeneric species so far examined. These cytogenetic data are discussed with respect to the previous ones in this subfamily and with other characters of taxonomic and evolutionary value.     

Chromosome numbers,C-banding patterns and sperm of some ladybird species from Central Europe (Coleoptera,Coccinellidae)

C-banded karyotypes were studied in the males of seven ladybird species from the subfamily Coccinellinae, viz. Adonia variegata (Goeze), Tythaspis sedecimpunctata (L.), Coccinella septempunctata (L.), Calvia decemguttata (L.), Calvia quatuordecimguttata (L.), Propylea quatuordecimpunctata (L.), Phyllobora vigintiduopunctata (L.). All the species, with the exception of Tythaspis sedecimpunctata (L.), possess 2n = 20, n(male) = 9 + Xy(p). Tythaspis sedecimpunctata (L.), however, has 2n = 24, n(male) = 11+Xy. The examined karyotypes show only a paracentromeric position of constitutive heterochromatin in all autosomes and the sex chromosome X, while the y heterochromosome is dot-like and wholly euchromatic. Successive stages of spermiogenesis were analysed.     

Karyotypic characterization of three weevil species (Coleoptera: Curculionidae, Brachyderini)

Karyotypes of three species, Brachyderes incanus, Brachysomus setiger and Paophilus afflatus, belonging to the tribe Brachyderini, were studied using C-banding technique. The species share the same chromosome number 2n = 22 and meioformula n = 10+Xy(p) at all metaphase 1 plates of spermatid division. Some differences between karyotypes were observed in terms of centromere positions and C-band sizes. Most chromosomes are meta- or submetacentric and form a graded series in respect to length. The chromosomes resemble one another in having a rather small amount of heterochromatin restricted to the pericentromeric region and visible as dark stained blocks mainly during early stages of nuclear division. Only in Brachyderes incanus do larger bands occur at mitotic metaphase and diakinesis. These cytogenetic data are in agreement with karyological findings obtained in other species of Brachyderini so far examined.     

Chromosomes of some Puerto Rican flea beetles (Coleoptera: Chrysomelidae: Alticinae): multiple cytogenetic evolutionary tendencies in the neotropics

Meiotic chromosomes of 10 West Indian flea beetles with restricted distribution, including eight Puerto Rican endemics, were studied. Two species of the cosmopolitan Longitarsus resemble Old World congenerics in having meioformulae 13 + Xy and 14 + Xy, both with one pair of enlarged autosomes. One unidentified species of Aphthona seems to have achiasmatic meiosis. Among the Puerto Rican endemics, repeated fusions have produced low-numbered karyotypes in Homoschema latitarsum (2 + neoXY, now the lowest meioformula known for the Chrysomelidae) and Heikertingerella krugi (4 + neoXY). Three species of Aedmon have 18 + Xy_p as a result of a series of centric fissions from the Polyphagan ancestral condition of nine pairs. Phyllotrupes sp. (a new genus record for Puerto Rico, near P. acutangula ) and Pseudodisonycha portoricensis have 17 + Xy and 16 + Xy, respectively, plus a swarm of supernumerary chromosomes.     

Karyological notes on six beetle species from Armenia (Coleoptera: Tenebrionidae,Cerambycidae, Curculionidae)

Karyotypic details were studied in males of six beetle species from three families, viz. Tenebrionidae: Dailognatha pumila Bdy. (2n = 20, n(male) = 9 + Xy(p)), Pachyscelis musiva Ménétr. (2n = 18, n(male) = 8 + Xy(p)), Pimelia capito Kryn. (2n = 18, n(male) = 8 + Xy(p)); Cerambycidae: Agapanthia walteri Reitt. (2n = 20, n(male) = 9+Xy(p)), Agapanthia korostelevi Danilevsky (2n = 20, n(male) = 9 + Xy(p)); Curculionidae: Phyllobius caucasicus Stierl. (2n = 22, n(male) = 10 + Xy(p)). The chromosome number and sex determining system of all beetle species are described for the first time. Evolutionary trends in karyotypes of the studied beetle groups are briefly discussed.     

C-banded chromosomes of the genus Bembidion Latr. (Coleoptera, Carabidae)

The C-banding pattern of Bembidion punctulatum, B. varium, B. varicolor, B. ascedens, B. tibiale, B. ustulatum, B. decorum, and B. modestum are presented. All examined species have a symmetrical karyotype with meta- and submentacentric chromosomes and meioformula n=11+XY. All of them have an achiasmatic spermatogenesis in common. The present data confirm earlier studies indicating a considerable morphological and numerical stability of the Bembidiini karyotype. The C-banding showed the existence of heterochromatin in the paracentric regions of chromosomes, and also 2-3 intercalar C-positive segments were observed. The Y chromosome is entrely euchromatic. The C-banded karyotype of the analysed species in genus Bembidion has large heterochromatin segments on chromosomes, an exception in Coleoptera.     

Karyotypes of nine species of Cicindelini and cytotaxonomic notes on Cicindelinae (Coleoptera,Carabidae)

The male meioformula of seven species of Cicindelini from the Iberian Peninsula and one species from Canada is 9+XXXY. In addition, female data of Cylindera paludosa corroborate previous reports of males. The Palearctic species show a generalized karyotype which presents specific modifications, but it is not possible to establish if it is also present in species of other faunas.Present data indicate that multiple sex chromosomes is an ancestral condition for the subfamily Cicindelinae. It is postulated that the meioformula of the tribe Cicindelini is 9 or 10 plus XXY and that trends in karyotypic evolution are partially related to the geographic distribution of lineages. Numerical deviations observed in the tribe can be explained by changes occurring independently in autosomes and heterosomes, so that autosome-heterosome fusions do not seem to be a generalized event. A number of criteria may be developed for determining the polarity of change of karyotypic characters, thus making cytotaxonomic studies a valuable tool for understanding the systematics of Cicindelini.     

Chromosomes of Trachypachus Motschulsky and the evolution of the ancestral adephagan karyotype (Coleoptera)

The family Trachypachidae is a critical group for understanding the evolution of the coleopteran suborder Adephaga. In this article, we report the first karyotypic data on Trachypachus showing a diploid number of 2n = 36 + X (meioformula n = 18 + X) and a single autosomal localization of the rDNA clusters. The evolutionary dynamics of this karyotype are discussed in the light of recent phylogenetic hypotheses of the order Coleoptera. We conclude that chromosome analysis supports a close relationship between trachypachids and the other Geadephaga and that a male karyotype with 36 + X chromosomes may well be considered ancestral for the whole suborder Adephaga.     

Karyology and Cytotaxonomy of the Genus Chrysolina Motschulsky (Coleoptera, Chrysomelidae)

Eight species of Chrysolina have been chromosomally studied in male individuals from Central Europe, South France and the Urals, in Russia. Ch. rufa had 2n = 23, Ch. purpurascens crassimargo 2n = 24 and a meioformula of 11 + Xy_p, Ch. globosa and Ch. bigorrensis 12 + Xy_p, Ch. umbratilis 2n = 30 and 14 + XY_p, a new non-chiasmate sex-chromosome system with both male sex-chromosomes of large size, Ch. cf. subcostata 12 + XY_p with large sex-chromosomes also, Ch. interstincta 2n = 40 and 19 + Xy_p, and Ch. obscurella 2n = 47. The taxonomic implications of these findings are discussed in relation with the current subgeneric classification of Chrysolina and principally that of the subgenera Colaphoptera, Sphaerochrysolina, Pleurosticha, Chalcoidea and Threnosoma.     

五种稻蝗染色体核型和C带带型的比较

本文研究了五种稻蝗Oxya chinensis、O. shanghaiensis、O. adentata、O. hyla intricara、O. agavisa的染色体核型和C带带型.玻片制备采用压片法,BSG法C带处理.结果表明:五种稻蝗染色体核型差异较小,具有属的保守性,但在C带方面则显示出一定的差别,种间染色体带型的差异大小与形态学上的差异程度具明显的正相关.其中小稻蝗和山稻蝗各自具有独特的带型结构,与其余三种显然不同,而中华稻蝗、上海稻蝗、无齿稻蝗虽在主要标志性染色体上带纹趋于一致,但在一些细微结构和统计数据方面存在一定差异.本文对五种稻蝗减数分裂中期Ⅰ的染色体数目和交叉定位也作了统计和比较,在染色体行为分析方面做了初步工作.据此,本文讨论了五种稻蝗的染色体分类问题.     

Chromosomal characteristics and karyotype evolution of Oxyopidae spiders (Araneae, Entelegynae)

We made a cytogenetic analysis of four species of Oxyopidae and compared it with the karyotype data of all species of this family. In Hamataliwa sp, the mitotic cells showed 2n♂ = 26+X(1)X(2) and telocentric chromosomes. The 2n♂ = 28, which has been described for only one oxyopid spider, is the highest diploid number reported for this family. Peucetia species exhibited distinct karyotype characteristics, i.e., 2n♂ = 20+X(1)X(2) in P. flava and 2n♂ = 20+X in P. rubrolineata, revealing interspecific chromosome variability within this genus. However, both Peucetia species exhibited telocentric chromosomes. The most unexpected karyotype was encountered in Oxyopes salticus, which presented 2n♂ = 10+X in most individuals and a predominance of biarmed chromosomes. Additionally, one male of the sample of O. salticus was heterozygous for a centric fusion that originated the first chromosomal pair and exhibited one supernumerary chromosome in some cells. Testicular nuclei of Hamataliwa sp and O. salticus revealed NORs on autosomal pairs, after silver impregnation. The majority of Oxyopidae spiders have their karyotype differentiated by both reduction in diploid number chromosome number and change of the sex chromosome system to X type; however, certain species retain the ancestral chromosome constitution 2n = 26+X1X2. The most remarkable karyotype differentiation occurred in O. salticus studied here, which showed the lowest diploid number ever observed in Oxyopidae and the second lowest registered for Entelegynae spiders.     

Alterations in cardiac contractile proteins due to oxygen free radicals.

In view of the potential role of free radicals in the genesis of cardiac abnormalities under different pathophysiological conditions and the importance of contractile proteins in determining heart function, this study was undertaken to examine the effects of oxygen free radicals on the rat heart myofibrils. Xanthine plus xanthine oxidase (X + XO) which is known to generate superoxide anions (O2-) and hydrogen peroxide (H2O2), an activated species of oxygen, was found to decrease Ca(2+)-stimulated ATPase activity, increase Mg(2+)-ATPase activity and reduce sulfhydryl (SH) group contents in myofibrils; these effects were completely prevented by superoxide dismutase (SOD) plus catalase (CAT). Both H2O2 and hypochlorous acid (HOCl), an oxidant, produced actions on cardiac myofibrils similar to those observed by X + XO. The effects of H2O2 and HOCl were prevented by CAT and L-methionine, respectively. N-ethylmaleimide (NEM) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), inhibitors of SH groups, also produced effects similar to those seen with X + XO. Dithiothreitol (DTT), a well known sulfhydryl-reducing agent, prevented the actions of X + XO, H2O2, HOCl, NEM and DTNB. These results suggest that marked changes in myofibrillar ATPase activities by different species of oxygen free radicals may be mediated by the oxidation of SH groups.     

Speciation and diversification of parasite lineages: an analysis of congeneric parasite species in vertebrates

The evolutionary diversification of living organisms is a central research theme in evolutionary ecology, and yet it remains difficult to infer the action of evolutionary processes from patterns in the distribution of rates of diversification among related taxa. Using data from helminth parasite communities in 76 species of birds and 114 species of mammals, the influence of four factors that may either be associated with or modulate rates of parasite speciation were examined in a comparative analysis. Two measures of the relative number of congeneric parasite species per host species were used as indices of parasite diversification, and related to host body mass, host density, latitude, and whether the host is aquatic or terrestrial. The occurrence of congeneric parasites was not distributed randomly with respect to these factors. Aquatic bird species tended to harbour more congeneric parasites than terrestrial birds. Large-bodied mammal species, or those living at low latitudes, harboured more congeneric parasites than small-bodied mammals, or than those from higher latitudes. Host density had no apparent association with either measures of parasite diversification. These patterns, however, reflect only the present-day distribution of parasite diversification among host taxa, and not the evolutionary processes responsible for diversification, because the apparent effects of the factors investigated disappeared once corrections were made for host phylogeny. This indicates that features other than host body size, host density, latitude, and whether the habitat is terrestrial or aquatic, have been the key driving forces in the diversification of parasitic helminth lineages. This revised version was published online in July 2006 with corrections to the Cover Date.     

Identifying Canadian mosquito species through DNA barcodes

A short fragment of mt DNA from the cytochrome c oxidase 1 (CO1) region was used to provide the first CO1 barcodes for 37 species of Canadian mosquitoes (Diptera: Culicidae) from the provinces Ontario and New Brunswick. Sequence variation was analysed in a 617-bp fragment from the 5' end of the CO1 region. Sequences of each mosquito species formed barcode clusters with tight cohesion that were usually clearly distinct from those of allied species. CO1 sequence divergences were, on average, nearly 20 times higher for congeneric species than for members of a species; divergences between congeneric species averaged 10.4% (range 0.2-17.2%), whereas those for conspecific individuals averaged 0.5% (range 0.0-3.9%).     

Plasmids of enterotoxigenic Escherichia coli H10407: evidence for two heat-stable enterotoxin genes and a conjugal transfer system

Three species of plasmids, associated with virulence and conjugal transfer, were identified in a clinically isolated enterotoxigenic Escherichia coli strain, H10407 (serotype O78:H11). pCS1, a non-self-transmissible plasmid species with a molecular weight of 62 X 10(6) and a 47 mol% guanine-plus-cytosine content, specified colonization factor antigen I and heat-stable enterotoxin (ST) production, as reported by others previously. A second non-self-transmissible plasmid species, designated pJY11, with a molecular weight of 42 X 10(6) and a 51 mol% guanine-plus-cytosine content, specified ST and heat-labile enterotoxin production and manifested T5/T6 phage restriction. The third plasmid species, pTRA1, also had a molecular weight of 42 X 10(6) and had a guanine-plus-cytosine content of 51 mol%; this species was self-transmissible and promoted transfer of both pCS1 and pJY11 to other bacterial cells. pCS1 may have originated from species of bacteria with a lower guanine-plus-cytosine content than E. coli. Finally, although demonstrating some heterogeneity with each other, both STs encoded by pCS1 and pJY11 belonged to the STa group.     

THE COMPARATIVE MORPHOLOGY OF THREE CYLINDROPUNTIAS

The three species discussed in this article have at one time been considered congeneric in Grusonia. Present evidence indicates the three are specifically distinct and should be congeneric, but as cylindropuntias in Opuntia. There seems to be no valid reason for retaining the genus Grusonia. Except for branching and decomposition, Opuntia bradtiana and O. santamaria are more similar anatomically and morphologically than O. kunzei is to either of the two.     

G- and C-banded karyotype of the markhor<Emphasis Type="Italic">Capra falconeri heptneri</Emphasis>, and comparison of its banding patterns with the Alpine ibex<Emphasis Type="Italic">Capra ibex</Emphasis> and cattle<Emphasis Type="Italic">Bos taurus</Emphasis>

Here we present the first data on chromosome banding forCapra falconeri heptneri (Zalkin, 1945) (Bovidae: Caprinae), a critically endangered subspecies of the markhor, and compare its G- and C-banding patterns with those of the congeneric Alpine ibexC. ibex Linnaeus, 1758 and the evolutionarily more distant cattleBos taurus Linnaeus, 1758. The two goat species have identical karyotypes whereasB. taurus, which has the same diploid number (2n = 60) and autosomal fundamental number (aFN) differs in the morphology of two pairs of autosomes (9 and 14) and of the X chromosome, as well as in the amount of C heterochromatin. Although the study supports the earlier idea of karyotype homogeneity within the genusCapra, new comparative cytogenetic data for unstudied yet congeneric and other related species are necessary for our understanding of the pattern of chromosome evolution within the subfamily Caprinae and, more broadly, the family Bovidae.     

Invasive and non-invasive lineages in Xenostrobus (Bivalvia: Mytilidae)

The mussel genus Xenostrobus comprises eight named extant species from the Indo-West Pacific, including Xenostrobus inconstans, Xenostrobus pulex and Xenostrobus securis from Australia, the latter two also occurring in New Zealand. Xenostrobus species are predominantly restricted to estuaries or sheltered marine habitats although X. pulex inhabits the rocky intertidal on open coasts. Xenostrobus has recently been suggested to be congeneric with the freshwater invasive species Limnoperna fortunei. Xenostrobus securis is itself invasive in the Far East and Europe. This study employed DNA sequences from cytochrome c oxidase (COI), the D1 expansion region of 28S rRNA and the internal transcribed spacers of the ribosomal cistrons to investigate species relationships and habitat transitions in Australasian Xenostrobus. It is unlikely that Xenostrobus and Limnoperna are congeneric as their COI sequences are very different. There was unexpected complexity in defining Xenostrobus species. Xenostrobus pulex from New Zealand is probably a distinct species to the Australian taxon of that name with the name X. neozelanicus available for that taxon. Xenostrobus inconstans and Australian X. pulex were not reciprocally monophyletic in COI analyses. The phylogeography of the COI haplotypes of X. securis suggests that it may be a cryptic species complex, although this possibility could not be confirmed by sequences of the other genes.     

On the reaction of molecular oxygen with thiyl radicals: a re-examination

Absolute rate constants for the addition of oxygen to thiyl radicals, i.e. RS. + O2----RSOO., have been determined by applying a new competition method based on RS. formation via one-electron reduction of the corresponding disulphides, and the competition between RS. reacting with O2 and an electron donor such as ascorbate. Bimolecular rate constants have been obtained for the thiyl radicals derived from cysteine (6.1 X 10(7) mol-1 dm3 s-1), penicillamine (2.5 X 10(7) mol-1 dm3 s-1), homocysteine (8.0 X 10(7) mol-1 dm3 s-1), cysteamine (2.8 X 10(7) mol-1 dm3 s-1), 3-thiopropionic acid (2.2 X 10(8) mol-1 dm3 s-1) and glutathione (3.0 X 10(7) mol-1 dm3 s-1), respectively. The values obtained for the O2 addition to the thiyl radicals from glutathione and cysteine are considerable lower (by about two orders of magnitude) than those previously published. This indicates that the RS. + O2 reaction may be of complex nature and is generally a process which is not solely controlled by the diffusion of the reactants.