Ranunculus sundaicus (Backer) Eichler (2n=16) from Java was karyologically and cytogenetically analyzed in relation to R. silerifolius Lév. (2n=16) from the Japanese Archipelago. Both the karyotype and external morphology of R. sundaicus was similar to those of the R. silerifolius Mugi-type. In addition, the behavior of meiotic chromosomes in the (R. sundaicus × R. silerifolius Mugi-type) F₁ hybrid was normal. It is concluded, therefore, that R. sundaicus is a synonym and a relic species of R. silerifolius. A higher plant growing on Java is karyologically defined for the first time in relation to R. silerifolius of the Japanese archipelago.

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Karyotype analysis and meiotic behavior in a dioecious cucurbit Coccinia grandis, carrying heteromorphic sex chromosomes, has been carried out using conventional and fluorochrome dyes. Distinct differences in karyotype formula with 15m+4M+2sm+2m: sm+1m: st for male plant and 14m+6M+2sm+2m: st for female plant were observed with orcein staining. In both cases one autosome pair with two constrictions was present. Male plants are seen to possess a heteromorphic Y chromosome with two constrictions which is sufficiently larger than other small sized chromosomes. Giemsa followed by CMA/ DAPI staining through EMA method applied for the first time in this dioecious species, revealed CMA-positive signals in different chromosomes. Detailed meiotic analysis has been carried out from diakinesis and metaphase I to establish genomic stability.

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In the present study, we provide distribution patterns of tandem repetitive DNA sequences on the chromosomes of two cucumber cultivars from India and Japan by FISH method. Four types of tandem repetitive DNA sequence Type I, Type II, Type III and Type IV were adopted as FISH probes. Probe of Type III repeats hybridized to the centromeric regions, while Type I/II and Type IV were detected in the telomeric region in both cultivars. However, different distribution patterns of the repeats were displayed in two cultivars, for example, Type III signals were not detected on the Chromosome 7 of Indian cucumber cultivar and Chromosome 5 of Japanese cucumber cultivar. Also, metaphase chromosomes of Japanese and Indian cucumber cultivars were identified individually by the FISH analysis. These results clarified that these sequences could be used as cytological markers for discrimination of cucumber chromosomes.

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We analyzed chromosomes of two species of Japanese fishflies (Megaloptera: Corydalidae: Chauliodinae), Parachauliodes continentalis and P. japonicus. The chromosome numbers in both species were 2n=20 consisting of 9 pairs of autosomes plus XX chromosomes in females and Xy in males. The X chromosomes were subtelocentric while the y was the smallest chromosome of the set. The sex chromosomes of first meiotic metaphase (MI) spermatocytes in both species invariably formed bivalents synchronously with the autosomes and formed parachute-type bivalents, suggesting that the species in this genus share a common sex bivalent mechanism.

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The genus Astyanax, one of the largest genera in the family Characidae, comprises a large number of similarly shaped fish species. In this study, the karyotypes of three sympatric species of Astyanax were analyzed. Astyanax asuncionensis showed a karyotype of 2n=50 chromosomes (14M+26SM+10ST/A). Astyanax lineatus also had 2n=50 chromosomes, but its karyotype was different (8M+24SM+18ST/A). Astyanax marionae showed a karyotype of 2n=48 chromosomes (8M+24SM+16ST/A). Ag-NORs appeared in two pairs of chromosomes in Astyanax marionae and in only one pair in the other two species. The variation in the karyotype formula and number of nucleolar organizer regions highlights the importance of these markers in distinguishing among similarly shaped species.

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Cytologically, Largidae is a very interesting family as it possesses low diploid number and large chromosome size. So far, only ten of its species belonging to two subfamilies Larginae (6) and Physopeltinae (4) have been analysed karyologically. In the present study male specimens of Physopelta gutta, P. quadriguttata and Neophysopelta schlanbuschi having the same chromosomal formula i.e., 2n=17=12A+2m+X₁X₂Y, were cytologically examined. The behaviour of the sex chromosomes during prophase-I has been found to be specific to each species. In P. gutta, all the three sex chromosomes remain separate throughout the diffuse stage and prophase-I. In P. quadriguttata, X₁ and Y remain closely associated while X₂ remains separate at the diffuse stage and prophase-I. In N. schlanbuschi, X₁, X₂ and Y form a single chromatin body at the diffuse stage that remains so throughout prophase-I. In P. gutta and P. quadriguttata, dispersed C-bands are observed in autosomal bivalents excepting one bivalent in P. gutta which shows two heavy terminal C-bands, while in N. schlanbuschi, all the bivalents are found to be C-negative. Sex chromosomes X₁, X₂ and Y exhibit heterogeneous C-banding pattern whereas m-chromosomes are found to be C-negative in all the three species. Most of the C-heterochromatin in autosomal bivalents is found to be DAPI/CMA₃ bright in P. quadriguttata but in P. gutta, base specificity of C-bands is not resolved. Sex chromosomes X₁ and Y are found to be DAPI/CMA₃ bright in all the three species while X₂ exhibits diverse response to fluorochromes. Differences in banding pattern can serve as useful cytological markers.

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The chromosomal distribution of C-band-positive heterochromatin was investigated in eight species of Pomacentridae belonging to the four genera Abudefduf, Plectroglyphidodon, Neoglyphidodon, and Chrysiptera. For all species studied, centromeric C-bands were observed in most chromosomes; however, clear interstitial and/or telomeric C-bands were found in only three species. The pattern of C-band distribution varied from simple to complex among the species. The simple pattern, with only small-sized centromeric C-bands located in most chromosomes, was observed in three species. The other five species showed larger and variably-sized centromeric C-bands. N. nigroris had the most complex pattern, with C-bands located in many terminal and interstitial regions in addition to most centromeric regions, and their band sizes were variable. The present results show that the chromosomes of pomacentrid fishes have often diversified, with quantitative and positional changes in C-band positive heterochromatin.

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The karyotype of the endemic Baikal amphipod Polyacanthiska calceolata Bazikalova, 1937 was analysed for the first time. A diploid number (2n=52) and general chromosome morphology (with a median centromere) are typical amongst Gammaridea. A peculiar feature of the karyotype was its pronounced symmetry caused by the presence of metacentric (equal-armed) chromosomes insignificantly varying in size (from 5 to 8 μm). Sex chromosomes have not been distinguished. Supernumerary B chromosomes were regularly found in the metaphase plates of embryos P. calceolata, and may serve as an adaptive mechanism of this species to perform migrations to areas of gas hydrate seeps.

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