Frequency of chromosome polymorphism in Rattus rattus collected in Japan

This paper deals with a population survey of chromosome polymorphism of Rattus rattus collected in Japan and the results of their test crosses. All the animals had diploid 42 chromosomes, but three chromosome pairs, Nos. 1, 9 and 13, were polymorphic in respect to acro- and subtelocentric chromosomes. Frequency of No. 1 chromosome polymorphism in 453 rats collected in 19 localities showed 343 rats (75.5%) with acrocentric homomorphic pair (A/A), 90 (19.9%) with aerocentric and subtelocentric heteromorphic pair (A/S) and the remaining 20 (4.4%) with subtelocentric homomorphic pair (S/S). All animals collected in northern and northwestern Japan showed only the A/A pair, while those collected in southern and southeastern Japan showed A/A, A/S and S/S polymorphism. The latter group was also classified into 3 populations (east, southeast and south) by the different frequency of the subtelocentric chromosome. Progeny tests revealed that segregation of A/A, A/S and S/S types from F₁ hybrids between various chromosome combinations was not significantly different from the theoretical one. However, the number of animals with A/S pair was always slightly higher than the other two types, while those with S/S pair slightly fewer. Local differences of the chromosome polymorphism in Japan were considered due to the result of migration and selection of the rats with S/S chromosome type.Contribution No. 817 from the National Institute of Genetics, Japan. Supported in part by a grant-in-aid from the Ministry of Education of Japan (Scientific Expedition in 1968, and No. 8801 in 1969).     

Chromosomal polymorphism in Rattus rattus (L.) collected in Kusudomari and Misima

Summary Chromosomes of Rattus rattus (L.), collected in Kusudomari (Nagasaki) and Misima (Sizuoka) were examined. The karyotype revealed a remarkable heteromorphism in chromosome no. 1. The homozygotic, i.e. standard type, was characterized by 13 pairs of telocentric and 7 pairs of metacentric chromosomes. Chromosome pair no. 1 was telocentric. X and Y chromosomes were also telocentrics. 18.4 per cent of rats from Kusudomari and 40 per cent from Misima showed heteromorphic pair in chromosome no. 1. One chromosome of the heteromorphic pair is conspicuous by the subtelocentric centromere. Total length of the telocentric chromosome of no. 1 is almost the same as of its subtelocentric partner. These facts indicate that the subtelocentric no. 1 chromosome might have arisen by a centromeric inversion of the telocentric chromosome. Individuals homozygous for the subtelocentric no. 1 chromosome could not be found in either population. The difference in the frequency of the dimorphics collected in Kusudomari and Misima was statistically significant. Possible causes of the difference are discussed.Dedicated to Professor H. Bauer on the occasion of his sixtieth birthday. — Contributions from the National Institute of Genetics, Misima, Japan, No. 533     

Resolution of sex chromosome constitution by genomic in situ hybridization and fluorescence in situ hybridization with (TTAGG) n telomeric probe in some species of Lepidoptera

We have developed a simple method to resolve the sex chromosome constitution in females of Lepidoptera by using a combination of genomic in situ hybridization (GISH) and fluorescence in situ hybridization with (TTAGG) _n telomeric probe (telomere-FISH). In pachytene configurations of sex chromosomes, GISH differentiated W heterochromatin and telomere-FISH detected the chromosome ends. With this method we showed that Antheraea yamamai has a standard system with a fully differentiated W–Z sex chromosome pair. In Orgyia antiqua, we confirmed the presence of neo-W and neo-Z chromosomes, which most probably originated by fusion of the ancestral W and Z with an autosome pair. In contrast to earlier data, Orgyia thyellina females displayed a neo-ZW₁W₂ sex chromosome constitution. A neo-WZ₁Z₂ trivalent was found in females of Samia cynthia subsp. indet., originating from a population in Nagano, Japan. Whereas another subspecies collected in Sapporo, Japan, and determined as S. cynthia walkeri, showed a neo-W/neo-Z bivalent similar to O. antiqua, and the subspecies S. cynthia ricini showed a Z univalent (a Z/ZZ system). The combination of GISH and telomere-FISH enabled us to acquire not only reliable information about sex chromosome constitution but also an insight into sex chromosome evolution in Lepidoptera.     

Banding pattern analysis of polymorphic karyotypes in the black rat by a new differential staining technique

Polymorphic karyotypes of black rats (Rattus rattus) collected in Japan, Australia and India were analysed by a new differential staining technique by which banding patterns in the metaphase chromosomes are revealed. The technique consists in two steps: immersion of slides in a mixture of 2 x SSC and 0.1% (w/v) SDS (sodium dodecyl sulfate) for a few seconds at room temperature, and staining in Giemsa. By this treatment characteristic banding patterns were obtained in each chromosome pair. From the banding pattern analysis, subtelocentric pairs No. 1 and 9, which are polymorphic in respect to the acrocentrics and the subtelocentrics, were proven to have originated by pericentric inversion in the acrocentrics. The origin of two large metacentrics observed in Australian and Indian black rats was confirmed to have been developed by Robertsonian fusion of the acrocentrics No. 4 and 7 and No. 11 and 12 present in the Asian type black rat.Contribution No. 873 from the National Institute of Genetics, Japan. Supported by a grant-in-aid from the Ministry of Education of Japan (Nos. 92159 and 92332).     

Evolution of karyotypes and differentiation in 13 Rattus Species

Karyotypes of 13 Rattus species collected in Asia and Oceania were analysed with special interest to karyotype evolution and species differentiation. They were classified into three groups according to their karyotype similarity. Four species (R. annandalei, R. exulans, R. muelleri and R. norvegicus) with 2n=42 and a karyotype similar to some of the polymorphic karyotypes in the Asian black rats (R. rattus) are classified into the first group. Pericentric inversion of some acrocentrics seemed to have caused the differentiation of these species. The other four species (R. bowersii, R. fuscipes, R. leucopus and R. conatus) with similar karyotypes as the above group, but lower chromosome numbers than 2n=42 are classified into the second group. Robertsonian fusion in some acrocentrics observed in the first group are suggested to have caused the development of the species in this group. The remaining four species (R. sabanus, R. canus, R. huang and R. niviventer) with karyotypes markedly different from the above two in having a fewer number of small metacentrics are classified into the third group. They seemed to be more primitive karyotypes than the other Rattus species. By the comparison between the polymorphic karyotypes in the black rat, and karyotypes in its related species it was suggested that the former had occurred as primary events to the differentiation of the latter. Parallelism between the karyotype evolution and the species differentiation was discussed.Contribution No. 874 from the National Institute of Genetics, Japan. Supported by a grant-in-aid from the Ministry of Education of Japan (No. 92159 and 92332).     

Intraspecific chromosome variation in Cebus apella (cebidae,platyrrhini): The chromosomes of the yellow breasted capuchin Cebus apella xanthosternos wied, 1820

Chromosome studies in six wild-caught specimens of Cebus apella xanthosternos showed a distinctive chromosome pair number 11 that made it possible to distinguish this subspecies from other Cebus apella. The characteristic chromosome pair had intercalar heterochromatin unlike the “standard” chromosome type of Cebus apella and other species of the same genus, in which this chromosome pair shows a large, terminal, heterochromatic block. A comparison at the chromosomal level between different Cebus apella populations suggests that chromosome 11 in Cebus apella xanthosternos is a derived chromosome that has probably become fixed in this subspecies, either by selection or by drift in a small isolated population.     

Karyotypes and serum transferrin patterns of hybrids between Asian and Oceanian black rats,Rattus rattus

Karyotypes and serum transferrin patterns were examined in Asian and Oceanian black rats (R. rattus). Japanese R. r. tanezumi and Malayan R. r. diardii had 2n=42, but Australian and New Guinea R. r. rattus showed 2n=38 chromosomes. F₁ hybrids between Japanese and Australian rats and Malayan and New Guinea rats had 2n=40 chromosomes which consists of the two genomes of both parents. Although various matings between the F₁ hybrids were made, only one F₂ male rat with 2n=39 chromosomes was obtained. The F₁ hybrids seem to be semisterile. Parental transferrin phenotypes were TfR in Japanese rats and TfCD in Oceanian rats. F₁ hybrids examined showed TfRD in both male and female and one F₂ hybrid had TfR type transferrin. Based on the above investigations, it is suggested that Asian and Oceanian black rats are geographically isolated and evolved different chromosomal and serum transferrin characteristics, but the sexual isolation of the two groups is incomplete at the present time.Contribution No. 826 from the National Institute of Genetics, Japan. Supported by a grant-in-aid from the Ministry of Education of Japan (Scientific Expedition in 1968, No. 8801 in 1969 and No. 9001 in 1970).     

Variation of C-bands in the chromosomes of several subspecies of Rattus rattus

All subspecies of black rats (Rattus rattus) used in the present study are characterized by having large and clear C-bands at the centromeric region. The appearance of the bands, however, is different in the subspecies. Chromosome pair No. 1 in Asian type black rats (2n=42), which are characterized by an acrocentric and subtelocentric polymorphism, showed C-band polymorphism. In Phillipine rats (R. rattus mindanensis) the pair was subtelocentric with C-bands, but in Malayan black rats (R. rattus diardii) it was usually acrocentric with C-bands. In Hong-Kong (R. rattus flavipectus) and Japanese black rats (R. rattus tanezumi) it was polymorphic with respect to the presence of acrocentrics with C-bands or subtelocentrics without C-bands. The other chromosomes pairs showed clear C-bands, but in Hong-Kong black rats the pairs No. 2 and 5 were polymorphic with and without C-bands. In Japanese black rats, 6 chromosome pairs (No. 3, 4, 7, 9, 11 and 13) were polymorphic in regard to presence and absence of C-bands, but the other 5 chromosome pairs (No. 2, 5, 6, 8 and 10) showed always absence of C-bands. Only pair No. 12 usually showed C-bands. C-bands in small metacentric pairs (No. 14 to 20) in Asian type black rats generally large in size, but those in the Oceanian (2n=38) and Ceylon type black rats (2n=40) were small. In the hybrids between Asian and Oceanian type rats, heteromorphic C-bands, one large and the other small, were observed. Based on the consideration of karyotype evolution in the black rats, the C-band is suggested to have a tendency toward the diminution as far as the related species are concerned.     

Molecular phylogeny,taxonomy, and distribution of French Unio species (Bivalvia,Unionidae)

A plethora of unionid names was established in the nineteenth century by the “Nouvelle Ecole”. Although naiad morphological plasticity is well documented, the currently recognized fauna, with 17 species and subspecies included in the French checklist for the Unio genus, is still based upon morphological characters only. Insights have been provided from molecular data elsewhere in Europe and North Africa, but the French fauna remains unstudied. We present a molecular phylogeny of the Unio genus in France based on COI, 16S and 28S genes; taking up all available data in Europe plus 273 specimens collected in all main French drainages. The results show that there are either three valid species in France, with U. pictorum and U. mancus synonymized, or five, with the subspecies U. crassus courtillieri elevated to species level. Subspecies were generally not recovered, which questions the evolutionary units tacitly implied by subspecific names. Although sampling topotypes is the most reliable way to evaluate the status of a nominal subspecies, major human-induced changes in aquatic hydrosystems challenge the method. Nevertheless, operational taxonomy has to rely on ground-truthed data and we propose to reduce the actual number of valid taxa in France to the seven observed operational taxonomic units.     

Taxonomy and distribution ofPresbytis melalophos group in Sumatera,Indonesia

Taxonomy of thePresbytis melalophos group in Sumatera has been based solely on the distinction in the pelage coloration and has been a subject of controversy. In the present study, extensive field observations were undertaken. Three species, i. e.P. melalophos, P. thomasi, andP. femoralis, are recognized in Sumatera based on the cranial morphology, pelage coloration, and vocalization. Subspecies of each species are revised, a new classification is proposed, and a new subspecies,Presbytis melalophos bicolor, is described. A detailed distribution map of species and subspecies is presented. No sympatry occurs between the species. Finally, a cladistic analysis is presented for the three species, based on the cranial characters; the branching sequence is first between theP. melalophos clade and theP. femoralis- P. thomasi clade and second between theP. femoralis clade and theP. thomasi clade.     

Zoonotic and non-zoonotic helminths in black rats of rain-fed and irrigated areas of Swat,Khyber Pakhtunkhwa,Pakistan

Present study was conducted to get information on helminth parasites of zoonotic importance among the black rats of district Swat, Pakistan. Two hundred and sixty nine rats were captured from agricultural ecosystem of the district using live captured traps from 2011 to 2013. Captured rats were anesthetized and surveyed for the presence of ectoparasites, then were carefully dissected for investigation of endoparsites. Helminth parasites of 8 species were identified. Presence of parasite was noticed in 23.7% of sampled rats. The infection rates of sampled rats was given in order of their infectivity as Syphacia obvelata 13(4.83%), Aspiculuris tetraptera 13(4.83%), Heterakis spumosa 12 (4.46%), Hymenolepis spp. 9(3.34%), H.diminuta 8(2.97%), Hymenolepis fusa 4(1.48%), Lutziella microacetabularae 4(1.48%) and Lutziella spp. 1 (0.37%). No significant difference (P < 0.4289) was found in prevalence of parasites among areas, crops, crop stages and sex of the host while adult rats were found more infected than sub-adults. S. obvelata and A. tetraptera were the most common species of helminths while Lutziella sp., 1 (0.37%) was found only in one host. Rattus rattus (the black rat) was regarded as the host of helminth parasites of zoonotic importance, therefore the hidden health hazards of this rodent species needed to be considered to prevent infectivity of humans. Current study was concluded that Rattus rattus harbored a wide variety of helminth parasites which shows a hidden risk to inhabitants of the region. Monitoring rats’ population in settle areas and educating the local community about the risk of rat borne parasitic diseases transmission through rats appears to be absolutely essential.     

On the synchorological and floristic trends and discontinuities in regard to the Japan-Liukiu-Formosa area

Conclusion and summary The author discussed the floristic and vegetational differences (a) between Formosa and the Philippines, especially between Botel Tobago and Formosa, (b) between Formosa and Continental China, (c) between Japan proper and Continental China together with Corea, Mandschuria and the eastern part of Siberia, (d) between Formosa and Japan proper, and then he discussed (e) the flora of the Liukius, especially the differences between the Yaeyama Islands and Formosa as well as between Yaku Shima and the Amami Islands. In addition he briefly outlined the vegetation of Formosa and Japan, especially the altitudinal distribution of various forest-communities.The conclusions confirmed the floristic discontinuity between Formosa and the Philippines already set forth by E. D. Merrill and several other botanists. Concerning the phytogeographical position of Botel Tobago, the writer confirms the opinion of T. Kano and R. Kanehira that the flora of Botel Tobago is an extension of that of the Batan-Babuyan Islands, the northern border of the Philippines.The floristic close-relation between Japan proper and Continental China is evident from the phytogeographical distribution of the genera of higher plants found in Japan.Data show that the Formosan flora, especially of the highland, is more closely related to the south-western part of China, and also to the Himalayan region, than to the other surrounding regions.The writer considers that the relationship of the flora of Japan proper to that of Formosa is rather weak. He thinks, however, that their floras and vegetations are related to each other through their mutual relation to the lowland and lower montane flora of Continental China situated besides both of them.It is concluded that the flora of the Liukius is an extension of the Formosan flora, judging by the distribution of the genera and species. Looking over the Japan-Liukiu-Formosa area, a conspicuous floristic and synchorological discontinuity is recognized between Yaku Shima and the Amami Islands, and it is conceivable that the Yaku Shima flora is a south-western extension of the flora of Kyushu or Japan proper, as well as the vegetation of Yaku Shima is closely related essentially to that of Japan proper.The writer and his cooperators adopted a new name of Ardisieto-Shiietum Sieboldi to the Shiia forest of Yaku Shima.The writer is unable to make any synchorological or plant-sociological precise comparison between Japan and Continental China along with the eastern part of Siberia and moreover between Formosa and Continental China, because of few or no plant-sociological detailed data of the continental area in the Far Eastern Asia.The author delivered a special lecture on this subject before the botany class in the National Taiwan University, Taipei, Formosa (Taiwan), on December 4^th 1953. — Contributions from the Department of Biology, Faculty of Science, Kyushu University, No. 38.     

Chromosome studies in Chiropotes satanas utahicki hershkovitz, 1985 (cebidae,platyrrhini): A comparison with Chiropotes satanas chiropotes

Karyological characterizations of C. s. utahicki (2n = 54) and C. s. chiropotes (2n = 54) showed that these two subspecies are chromosomally very similar. In a single, isolated specimen of C s. utahicki, however, a derived, biarmed, chromosome 14 was found in the heterozygous condition. This variant chromosome was identical with pair 10 in C. s. chiropotes in which this chromosome type was apparently fixed. Chromosome differences between these subspecies might be transitional, leading to the establishment of two different karyomorphic populations derived from a once uniform karyotypic group that split into separate allopatric subspecies. © 1992 Wiley-Liss, Inc.     

Chromosome analysis of walking catfish,Clarias magur (Teleostei,Siluriformes, Clariidae), using staining,FISH with 18S, 5S and BAC probes

The chromosomal characteristics of Clarias magur were examined using conventional (Giemsa-staining, Ag-impregnation and CMA₃ + DAPI fluorescence) and molecular/ FISH (18S & 5S rDNA probes + one BAC DNA probe) cytogenetic tools. The diploid chromosome number was 50 and the karyotype consisted of 14 metacentric, 20 sub-metacentric, 8 sub-telocentric, 8 acrocentric chromosomes with 84 chromosome arms without any heteromorphic pair. The C-heterochromatic blocks were located on centromeric position of 13 pairs of chromosomes. The NOR sites, visualized by AgNO₃- and CMA₃- staining, were situated at p arms of chromosome pair No. 21, which also corresponded to 18S rDNA site visualized by FISH. The FISH signal of ICF_001_D19 clone probe was observed on 18th chromosome pair. The findings of the present study on C. magur provided valuable markers for the chromosome identification and locations of genes of the BAC clone on the chromosome will lead to the construction of physical map of genome of this species.     

Frequencies of chromosome polymorphism in pairs no. 1, 9, and 13 in three geographical variants of black rats,Rattus rattus

Frequencies of the acrocentric and subtelocentric polymorphism in pairs no. 1, 9 and 13 chromosomes have been examined in 358 black rats, Rattus rattus, distributed over several countries of Asia, Australia and United States. The black rats are divided into three geographical types by the different chromosome numbers, such as Asian (2n=42), Ceylon (2n=40) and Oceanian types (2n=38). Pairs no. 13 polymorphism was found widely in these all types, but the pair no. 1 and 9 polymorphisms were found in only Asian type black rats. In the Asian type rats, however, those distributed in northern India and Pakistan showed always the subtelocentric pairs no. 1 and 9 like as those in Ceylon and Oceanian type black rats. This finding supports that the Ceylon and Oceanien type rats have developed in India or Pakistan from the Asian type. The present study also suggests that inversion of the pair no. 13 could have occurred in earlier period than those of the pairs no. 1 and 9.     

PATTERNS OF FLORAL NECTAR-SUGAR COMPOSITION OF IPOMOPSIS LONGIFLORA (POLEMONIACEAE) NEAR THE CONTACT ZONE OF ITS SUBSPECIES LONGIFLORA AND AUSTRALIS

The nectar-sugar compositions of 338 individuals from 27 populations in two subspecies of Ipomopsis longiflora from Arizona, New Mexico, Texas, and Chihuahua were determined by high-performance liquid chromatography. Mean sucrose compositions of populations ranged from 73.2% to 91.9%, and the standard deviations ranged from 1.9% to 9.1%. Pairs and aggregates of populations were statistically compared. The nectar-sugar compositions of the two subspecies were significantly different as aggregates. Subspecies australis averaged 9.5% fructose, 7.9% glucose, and 82.6% sucrose while subspecies longiflora averaged 7.8% fructose, 5.7% glucose, and 86.5% sucrose. Each subspecies was found to have two groups of populations. Groups of higher sucrose populations were found along the contact zone of the subspecies; away from the contact zone both subspecies had groups of lower sucrose populations. The data show that significant variability exists in this biochemical character, and the pattern of variation is clearly related to the geographic distribution of the populations. The genetic and selective mechanisms involved are unknown.     

Subtle topographical differences along a floodplain promote different plant strategies among Paspalum dilatatum subspecies and populations

It was hypothesised that subtle topographical differences might cause the existence of ecotypes along a floodplain. The apomict grass Paspalum dilatatum subspecies dilatatum inhabits flood‐prone lowlands as well as nearby uplands in the floodplains of Argentina, while the sexual P. dilatatum subspecies flavescens almost exclusively inhabits the uplands. The aim of the present study was to identify the different traits that allow these P. dilatatum populations to inhabit different habitats. Plants of P. dilatatum were reciprocally transplanted between uplands and lowlands. Morphophysiological traits related to flooding tolerance were measured during a flood. Subspecies dilatatum from the uplands and subspecies flavescens showed a high physiological performance in the uplands but a considerable decrease in stomatal conductance, net photosynthesis rates and tiller number in the flooded lowlands. In contrast, the subspecies dilatatum from the lowlands showed relatively lower and stable stomatal conductance, photosynthesis rates and leaf water potential at both sites. Subspecies dilatatum from the lowlands outperformed upland populations at the lowland site with respect to tillering. Leaves of subspecies dilatatum from the lowlands that had grown at the lowland habitat had a lower blade/sheath proportion than leaves of plants transplanted to the uplands. This behavior did not occur in both upland populations. Results suggest that dilatatum Lowland plants have the typical strategy of stress‐tolerant genotypes and that the upland populations are adapted to habitats where competitive species are selected. In conclusion, habitats with subtle differences in topographic level can favour both ecotypic differentiations within an apomict subspecies but also the maintenance of morphophysiological similitudes between coexisting upland populations belonging to different subspecies.     

Cytogenetic characterization of the sole Solea senegalensis (Teleostei: Pleuronectiformes: Soleidae): Ag-NOR, (GATA) n , (TTAGGG) n and ribosomal genes by one-color and two-color FISH

A cytogenetic analysis of the sole Solea senegalensis was carried out using silver staining for the nucleolus organizer region (Ag-NOR) identification, one-color FISH for chromosomal mapping of 45S and 5S ribosomal DNAs (rDNAs), (GATA) _n , and (TTAGGG) _n , and two-color FISH for co-localization of both rDNAs. The Ag-NORs and the 45S rDNA were mapped to a medium-sized submetacentric chromosomal pair. Hybridization with the 5S rDNA showed a major signal on the short arm of a medium-sized submetacentric chromosome pair and a minor signal on a centromeric site of a small acrocentric chromosome pair. Differences in the Ag-NOR and 45S and 5S rDNAs FISH signal sizes were observed between homologous chromosomes and among individuals. A two-color FISH co-localized 45S and 5S rDNAs to a medium-sized submetacentric chromosomal pair. The hybridization with the telomeric (TTAGGG) _n repeat displayed small signals at all chromosomal telomeres. Finally, the (GATA) _n probe produced dispersed and small hybridization signals on all chromosome spreads, showing its ubiquitous existence in the genome. These results were compared with those from other Pleuronectiformes and discussed in terms of karyotype evolution.