Characteristics of quantitative variability of karyotype in cell line of fibroblasts from indian muntjac

The numerical regularities of karyotypic variability in cell line of the Indian muntjac skin fibroblasts (Muntiacus muntjak) has been studied. It was found that the karyotypic structure of cell population is mainly determined by some number of specific variant deviations from the main structural variant of karyotype (MSVK) to be depended on internal connections between chromosomes. Specific regulations determining the karyotypic structure of cell population are: 1) nonrandom character of cell distribution according to the number of chromosomal deviations from MSVK; 2) specific character of deviations in each chromosome from MSVK; 3) presence of significant connections between individual chromosomes by simultaneous mainly single directed numeral deviations. Results presented in this investigation were thought owner by analysing the number of individual chromosomes. These results extend considerably the known ideas of regulations of karyotypic variability in cell populations in vitro.     

The study of quantitative karyotypic variability by induction of chromosomal instability in cultured cells of the Indian muntjac skin fibroblasts

The influence of mycoplasmal contamination and somatic cell hybridization on the character of karyotypic variability in cell cultures of Indian muntjac skin fibroblasts has been investigated. Mycoplasma arginini and Acholeplasma laidlawii, used as factors inducing chromosomal instability, do not break the main regulations peculiar to intact control. They regulations are: 1) nonrandom character of cell distribution according to the number of chromosomal deviations from MSVK; 2) specific character of deviations of each chromosome from MSVK; 3) presence of significant connections between separate chromosomes by simultaneous mainly single directed numeral deviations. However, mycoplasmal contamination promotes the increase in the number of deviations in the direction of a decreasing chromosomes number. There is a breach of some connections between chromosomes by simultaneous deviations. They are chromosomes with broken connections according to the number of deviations which form telomeric associations (dicentrics). The number of these associations excel essentially intact control. The formation of new MSVK in subline M2 cells of the Indian muntjac in the process of chromosomal segregation in cell hybrid (M2 x clone of JF1 rat Jensen sarcoma) depends on the presence of significant connections between chromosomes by simultaneous numerical deviations in direction of MSVK formation. They are chromosomes that take part in the formation of new MSVK which form telomeric associations. These associations can be observed till stabilization of new MSVK. Probably, the support of the balance of karyotypic structure by factors inducing chromosomal instability is connected with change of some connections between chromosomes according to the number by simultaneous deviations as well as with the formation of dicentrics.     

Characteristics of quantitative karyotypic variability in cell line of kidney from rat kangaroo (Potorous tridactylis)

The goal of this work was to investigate the numeral karyotypic variability in different sublines (MT, M2). These sublines are formed spontaneously from the main cell line (M) and have modal number of chromosomes 9 and 10, MSVK (main structural variant karyotype)--3 + 3 + 1 + 2 and 3 + 4 + 2 + 1. There are general regulations which were originally got for the line M. In particular: 1) nonrandom character of cell distribution according to the number of chromosomal deviations from MSVK; 2) specific character of deviations of each chromosome from MSVK; 3) presence of significant connections between separate chromosomes by simultaneous, mainly single directed numeral deviations. These three lines (M, MT, M2) were compared and some differences were found: 1) different frequencies of deviations from MSVK; 2) the same chromosomes have tendency to different numeral deviation; 3) the specificity of some significant connections between separate chromosomes by simultaneous numeral deviations. These results lead us to a conclusion that the balance of numerical karyotypic structure in cell populations depends on the regulations connected with the character of deviations according to the number of chromosomes from MSVK which has the largest selected advantage. Each line has its own specific limits of karyotypic variability.     

Effect of cultivation conditions on the karyotype structure of a cell subline of the kangaroo rat kidney

Variations in cultivation conditions were found to exert influence on the distribution of cells for chromosome number by changing the modal class. The change of the HMEM medium for the EMEM medium during 2-6 passages results in the appearance of a new modal class with 16 chromosomes. The change in the chromosome number is preferably due to the loss of one X chromosome within the main structural variant of the karyotype (MSVK). On the other hand, the change of the HMEM medium for the F12 medium during 4-6 passages does not affect the cell distribution for the chromosome number. A comparative analysis of the total frequency of the MSVK cells and that of MSVK cells of the modal class showed that the karyotypic changes took place in all the variants, both in the modal class and beyond it due to other additive SVK. An exception is the variant NBLD (change of HMEM for the F12 during 6 passages). In this case chromosome changes occur mostly in the modal class, primarily due to the redistribution of chromosomes in groups. In all the variants there is an insignificant frequency of chromosomes, morphologically different from the MSVK. This confirms the findings according to which chromosomal changeability in the NBLD may be associated mostly with the change in the number of homologous chromosomes rather than with chromosomal aberrations. The frequency of chromosomal aberrations is the same in all the variants examined. The dependence of karyotypic characteristics on culture media mentioned above indicate that care should be taken in choice of culture conditions for permanent cell lines.     

Effect of laminin on numerical karyotype variability of kangaroo rat kidney cell lines

The numerical karyotypic variability has been investigated in "markerless" epithelial-like Rat kangaroo kidney cell lines NBL-3-11 and NBL-3-17 on cultivation on a laminin-2/4 coated surface. In cell line NBL-3-17, cultivated on the laminin-coated surface for 2, 4 and 12 days, the character of numerical karyotypic variability has changed. In 2 days the general character of cell distribution for the chromosome number did not change, but the frequency of cells with modal number of chromosomes decreases significantly, while that of cells with lower chromosome number show a tendency to increase. At a prolongation of cultivation time to 4 and 12 days, the numerical karyotypic heterogeneity in cell population increases due to a significant change in the general character of cell distribution for the chromosome number, which is caused by a significant decrease in the frequency of cells with the modal number of chromosomes, and by an increase in the frequency of cells with lower chromosome number. The analysis of distribution of individual chromosomes showed that the number of types of additional structural variants of the karyotype (SVK) increases significantly on cultivation on laminin for 2-12 days. In cell line NBL-3-11, cultivated on the laminin-coated surface for 2 and 4 days, the character of numerical karyotypic variability did not change compared to control variants. Possible reasons of the observed changes of numerical karyotypic variability in cell line NBL-3-17 is discussed. The reason of differences in the character of numerical karyotypic variability between cell lines NBL-3-11 and NBL-3-17 possibly consists in the change of gene expression, namely in a dose of certain functioning genes. The polymerase chain reaction with arbitrary primers revealed no differences between DNA patterns of cell lines NBL-3-17 and NBL-3-11. This can reflect a similarity in the primary DNA structure of both cell lines. Hence, these lines differ only in the number of homologous chromosomes (hypotriploid and hypodiploid).     

The effect of immobilized fibronectin on karyotypic variability in the skin fibroblast cell subline of indian muntjac

The numerical and structural karyotypic variability has been investigated in the Indian muntjac skin fibroblast cell subline MT on cultivating cells on the fibronectin-coated surface. In cell subline MT, cultivated on the fibronectin-coated surface for 1 and 2 days, the character of cell distribution for the chromosome number did not change. In 3, 4 and 8 days, the character of cell distribution for the chromosome number changed. These changes involve a significant decrease in frequency of cells with modal numbers of chromosomes, and an increase in frequency of cells with lower chromosome numbers. Many new additional structural variants of the karyotype (SVK) appear. The observed alterations seem to be due to both disturbances of mitotic apparatus and selection of SVK, which are more advantageous to changed culture conditions of the cell population. Detachment of cells from the fibronectin-coated surface, followed by a 1 day cultivation on a hydrophilic surface, commonly used for routine cell cultivation, does not restore the control cell distribution for the chromosome number, but cultivation in these conditions for 5 days restore control distribution. The frequency of chromosomal aberrations on cultivation on the fibronectin-coated surface for 3 and 4 days significantly increases, mainly at the expence of dicentrics (telomeric association). On prolongating the time of cultivation up to 8 days on the fibronectin-coated surface the frequency of chromosomal aberrations approaches the control value. Structural instability of chromosomes at cultivation on the fibronectin-coated surface demonstrates nonspecific reaction of "markerless" cell lines to unfavourable factors of the environment. We discuss possible reasons of differences in the character of karyotypic variability in cell lines of the Indian muntjac skin fibroblasts on cultivating on laminin and fibronectin.     

The influence of immobilized fibronectin on karyotypic variability of two rat kangaroo kidney cell lines

The numerical and structural karyotypic variability has been investigated in "markerless" Rat kangaroo kidney cell lines NBL-3-17 and NBL-3-11 when cultivating on a fibronectin-coated surface. In cell line NBL-3-17, cultivated on the fibronectin-coated surface for 1, 2, 4 and 8 days, the character of cell distribution for the chromosome number has changed. These changes involve a significant decrease in frequency of cells with modal number of chromosomes, and an increase in frequency of cells with lower chromosomal number. Many new additional structural variants of the karyotype (SVK) appear. The observed alterations seem to be due preference adhesion of cells with lower chromosome number, disturbances of mitotic apparatus and selection of SVK, which are more adopted to changes in culture conditions. Detachment of cells from the fibronectin-coated surface, followed by 5 days cultivation on a hydrophilic surface restored control distribution. In cell line NBL-3-11, cultivated on the fibronectin-coated surface for 1, 2, 4 and 8 days, the character of numerical karyotypic variability did not change compared to control variants. In cell line NBL-3-17 the frequency of chromosomal aberrations under cultivation on the fibronectin-coated surface for 1, 2, 4 and 8 days did not change relative to control variants. In cell line NBL-3-11 the frequency of chromosomal aberrations under the same conditions significantly increases, mainly at the expence of chromosomal, chromatid breaks and dicentrics (telomeric association) relative to control variants. We discuss possible reasons of differences in the character of numerical and structural karyotypic variability between cell lines NBL-3-17 (hypotriploid) and NBL-3-11 (hypodiploid) under cultivation on fibronectin. The reasons of the observed interline karyotypic differences possibly consist in peculiarity of karyotypic structure of cell line NBL-3-11 and in the change of gene expression, namely in a dose of certain functioning genes in the hypotryploid cell line NBL-3-17.     

Effect of immobilized laminin on karyotypic variability in two karyotypically different variants of the indian muntjac skin fibroblast cell line

The numerical and structural karyotypic variability has been investigated in MTs of the markerless cell line of Indian muntjac skin fibroblasts, as well as in its karyotypic variant MT^D cultivated on a laminin 2/4 coated surface. In the MT cell line preincubated in serum-free medium for 2.5 and 1.0 h, then cultivated on a laminin-coated surface in serum-containing medium for one, two, and three days, the character of cell distribution for the chromosome number has changed. These changes involve a significant decrease in the frequency of cells with modal numbers of chromosomes and an increase in frequency of cells with lower chromosome numbers. Some new additional structural variants of the karyotype (SVK) appeared. The observed alterations seem to be due to disturbances of the chromosome segregation and the establishment of a new advantageous balanced karyotypic structure. In the karyotypic variant MT^D differing from MT by an increased number of dicentrics (telomeric associations) cultivated under the same conditions, the character of cell distribution for the chromosome number did not change. In the MT cell line, the frequency of chromosomal aberrations did not change relative to control variants. In the karyotypic variant MT^D under the same conditions, the frequency of chromosomal aberrations significantly increased after three days mainly due to the formation of dicentrics. These results confirm the conclusion that, like aneuploidy, the formation of dicentrics in markerless cell lines appears to be the way in which the cell population adapts to unfavorable environmental factors. Possible reasons for differences in the character of the numerical and structural karyotypic variability between the MT cell line and its karyotypic variant MT^D are discussed.     

Effect of laminin on karyotypic variability in cell line of Indian muntjac skin fibroblasts

The numerical and structural karyotypic variability has been investigated in the Indian muntjac skin fibroblasts cell line M and karyotypic variant of this line M' on cultivation on a laminin 2/4 coated surface. In cell line M, cultivated on the laminin-coated surface for 4 and 14 days, and in karyotypic variant M', cultivated for 2, 4 and 14 days, the character of cell distribution for the chromosome number has changed. These changes involve a significant decrease in frequency of cells with model numbers of chromosomes, and an increase in frequency of cells with lower chromosome numbers. As a result, new modal chromosome numbers form. The frequency of cells with 4 chromosomes increases significantly; as a rule, such cells are absent in the control cell variants. Many new additional structural variants of the karyotype (SVK) appear. Detachment of cells M' from the laminin-coated surface followed by a 2 day cultivation on a hydrophilic surface, commonly used for routine cell cultivation, does not restore the control cell distribution for chromosomal number. The frequency of chromosomal aberrations on cultivation of the laminin-coated surface does not change relatively to controls. The observed alterations seem to be due to both disturbances of mitotic apparatus and selection of SVK, which are more advantageous to changed culture conditions of the cell population.     

Comparative sequence analyses reveal sites of ancestral chromosomal fusions in the Indian muntjac genome

Background

Indian muntjac (Muntiacus muntjak vaginalis) has an extreme mammalian karyotype, with only six and seven chromosomes in the female and male, respectively. Chinese muntjac (Muntiacus reevesi) has a more typical mammalian karyotype, with 46 chromosomes in both sexes. Despite this disparity, the two muntjac species are morphologically similar and can even interbreed to produce viable (albeit sterile) offspring. Previous studies have suggested that a series of telocentric chromosome fusion events involving telomeric and/or satellite repeats led to the extant Indian muntjac karyotype.

Results

We used a comparative mapping and sequencing approach to characterize the sites of ancestral chromosomal fusions in the Indian muntjac genome. Specifically, we screened an Indian muntjac bacterial artificial-chromosome library with a telomere repeat-specific probe. Isolated clones found by fluorescence in situ hybridization to map to interstitial regions on Indian muntjac chromosomes were further characterized, with a subset then subjected to shotgun sequencing. Subsequently, we isolated and sequenced overlapping clones extending from the ends of some of these initial clones; we also generated orthologous sequence from isolated Chinese muntjac clones. The generated Indian muntjac sequence has been analyzed for the juxtaposition of telomeric and satellite repeats and for synteny relationships relative to other mammalian genomes, including the Chinese muntjac.

Conclusions

The generated sequence data and comparative analyses provide a detailed genomic context for seven ancestral chromosome fusion sites in the Indian muntjac genome, which further supports the telocentric fusion model for the events leading to the unusual karyotypic differences among muntjac species.     

The influence of a substrate including extracellular matrix proteins on karyotypic variability in two cell lines of Indian muntjac skin fibroblasts

The influence of cell-culture conditions on numerical and structural karyotypic variability has been investigated in two Indian muntjac skin fibroblast “markerless” cell lines, M and MT. The cells were cultivated on a substrate consisting of extracellular matrix proteins (ECMs) synthesized by human mesenchymal stem cells (SC5-MSC). The character of cell distribution for the chromosome number of the cell line M changed after cultivation for 1 and 4 days as compared to control cells, which were cultured on a hydrophilic surface without ECM coating. These changes involve a significant decrease in frequency of cells with the modal numbers of chromosomes and an increase in frequency of cells with lower chromosome numbers. Many new types of additional structural variants of the karyotype (SVK) appear. The MT cell line, differing from M line in the number of homologous chromosomes, exhibited a character of cell distribution similar to that of the M line for the chromosome number for only 1 day after cultivation on the ECM substrate, but not after 4 days under the same culture conditions, when no difference from the control cells was observed. Further cultivation of MT cells for 8 days did not change the character of cell distribution for the chromosome number relative to the control variant. The observed alterations seem to be due to disturbances in the correct chromosome-segregation process, which were caused by an abrupt shift in the cell-culture conditions. Analysis of the structural karyotypic variability revealed a significant increase in frequency of chromosomal aberrations in the M cell line for 1 and 4 days in culture on the ECM substrate as compared to the control cells. The frequency of dicentric chromosomes (telomeric associations) was increased and constituted more than 50% of all chromosome aberrations. No increase in frequency of chromosome aberrations was observed for MT cells cultured under the same conditions. It can be suggested that the differing by the karyotypic structure, but the genetically identical cell lines have different response to the substrate. In contrast to the M line, in the MT line, a fast normalization of numerical karyotypic characteristics and no enhancement of structural karyotypic variability takes place. This provides a possibility to cultivate an MT cell on the given protein substrate while maintaining a balanced karyotypic structure characteristic of MT cell line.     

Effect of laminin on structural karyotype variability of kangaroo rat kidney cell lines

The structural karyotypic variability has been investigated in the "markerless" epithelial-like Rat kangaroo kidney cell lines NBL-3-17 and NBL-3-11 on cultivation on a laminin-2/4 coated surface. In cell line NBL-3-17, cultivated on the laminin-coated surface for 2, 4 and 12 days, and in cell line NBL-3-11, cultivated on the laminin-coated surface for 2 and 4 days, there is a significant increase in the frequency of chromosomal aberrations, both chromosomal breaks and dicentrics (telomeric associations). Different sensitivity of individual chromosomes to inducing chromosomal breaks was observed in addition to a preferential involvement of some chromosomes in dicentric formation. Structural instability of chromosomes at cultivation on laminin demonstrates nonspecific reaction of the "markerless" cell lines to unfavourable factors of the environment. We discuss possible reasons of differences in the character of karyotypic variability between a cell line of the Indian muntjac skin fibroblasts and epithelial-like Rat kangaroo kidney cell lines cultivated on laminin.     

Characterization of ancestral chromosome fusion points in the Indian muntjac deer

Tandem fusion, a rare evolutionary chromosome rearrangement, has occurred extensively in muntjac karyotypic evolution, leading to an extreme fusion karyotype of 6/7 (female/male) chromosomes in the Indian muntjac. These fusion chromosomes contain numerous ancestral chromosomal break and fusion points. Here, we designed a composite polymerase chain reaction (PCR) strategy which recovered DNA fragments that contained telomere and muntjac satellite DNA sequence repeats. Nested PCR confirmed the specificity of the products. Two-color fluorescence in situ hybridization (FISH) with the repetitive sequences obtained and T₂AG₃ telomere probes showed co-localization of satellite and telomere sequences in Indian muntjac chromosomes. Adjacent telomere and muntjac satellite sequences were also seen by fiber FISH. These data lend support to the involvement of telomere and GC-rich satellite DNA sequences during muntjac chromosome fusions.Communicated by E.A. NiggAccession numbers: AY322158, AY322159, AY322160     

Defining the orientation of the tandem fusions that occurred during the evolution of Indian muntjac chromosomes by BAC mapping

The Indian muntjac (Muntiacus muntjak vaginalis) has a karyotype of 2n=6 in the female and 7 in the male, the karyotypic evolution of which through extensive tandem fusions and several centric fusions has been well-documented by recent molecular cytogenetic studies. In an attempt to define the fusion orientations of conserved chromosomal segments and the molecular mechanisms underlying the tandem fusions, we have constructed a highly redundant (more than six times of whole genome coverage) bacterial artificial chromosome (BAC) library of Indian muntjac. The BAC library contains 124,800 clones with no chromosome bias and has an average insert DNA size of 120 kb. A total of 223 clones have been mapped by fluorescent in situ hybridization onto the chromosomes of both Indian muntjac and Chinese muntjac and a high-resolution comparative map has been established. Our mapping results demonstrate that all tandem fusions that occurred during the evolution of Indian muntjac karyotype from the acrocentric 2n=70 hypothetical ancestral karyotype are centromere–telomere (head–tail) fusions.     

Comparative Chromosome Painting in Mammals: Human and the Indian Muntjac (Muntiacus muntjak vaginalis)

We have used human chromosome-specific painting probes forin situhybridization on Indian muntjac (Muntiacus muntjak vaginalis,2n= 6, 7) metaphase chromosomes to identify the homologous chromosome regions of the entire human chromosome set. Chromosome rearrangements that have been involved in the karyotype evolution of these two species belonging to different mammalian orders were reconstructed based on hybridization patterns. Although, compared to human chromosomes, the karyotype of the Indian muntjac seems to be highly rearranged, we could identify a limited number of highly conserved homologous chromosome regions for each of the human chromosome-specific probes. We identified 48 homologous autosomal chromosome segments, which is in the range of the numbers found in other artiodactyls and carnivores recently analyzed by chromosome painting. The results demonstrate that the reshuffling of the muntjac karyotype is mostly due to fusions of huge blocks of entire chromosomes. This is in accordance with previous chromosome painting analyses between various Muntjac species and contrasts the findings for some other mammals (e.g., gibbons, mice) that show exceptional chromosome reshuffling due to multiple reciprocal translocation events.     

The effect of culturing conditions on the karyotypic structure of two cell sublines of Indian muntjak skin fibroblasts

The "therapeutic" doses of antibiotics, routinely applied to prevent microbial contamination in cultured cells, decrease the frequency of modal class cells and increase that of cells of other classes in sublines of Indian muntjak skin fibroblasts. In MT-subline, with 9 chromosomes in the modal class, the loss of cells with some large chromosomes occurred almost frequently. In terms of the formula of the karyotype main structural variant, this change is described as (-1-0-1-1). In M-subline, with 7 chromosomes in the modal class, the similar result is mainly achieved due to a decrease in the cell number with Y1-chromosome to be described as (0-0-0-0-1). The study of frequency of deviation from the chromosome number in the MSVK has shown that in the MT-subline, rather than in the M-subline, different chromosomes are incidentally involved in the karyotypic rearrangement. In both the sublines antibiotics induced chromosomal aberrations, primarily increasing the number of dicentrics. Preferential involvement of some chromosomes in the dicentric formation was observed. Cytogenetical parameters are more affected by antibiotics in the MT-subline. The data obtained indicate that even low concentrations of antibiotics may induce karyotypic changes in cells cultures.     

New evidence for tandem chromosome fusions in the karyotypic evolution of Asian muntjacs

A clone of highly repetitive DNA, designated C5, was isolated from DNA of female Chinese muntjac cells. The nucleotide sequence of this clone is 80%–85% homologous to that of the satellite IA clone and other highly repetitive DNA clones previously obtained from the Indian muntjac. Using C5 as a probe for in situ hybridizations to chromosome preparations of cells of both the Chinese and Indian muntjacs, we were able to show that these repeated sequences occur in centromeric heterochromatin of the chromosomes of both Chinese and indian muntjac species. More significantly, non-random clusters of hybridization signals were detected on the arms of chromosomes of the Indian muntjac. These latter hybridization sites are postulated to be regions of interstitial heterochromatin and could be the remnants of centromeric heterochromatin from ancestral Chinese muntjac chromosomes. Our observations provide new supportive evidence for the tandem chromosome fusion theory that has been proposed for the evolution of the Indian muntjac karyotype.by P.B. Moens     

New insights into the karyotypic relationships of Chinese muntjac (Muntiacus reevesi), forest musk deer (Moschus berezovskii) and gayal (Bos frontalis)

To investigate the karyotypic relationships between Chinese muntjac (Muntiacus reevesi), forest musk deer (Moschus berezovskii) and gayal (Bos frontalis), a complete set of Chinese muntjac chromosome-specific painting probes has been assigned to G-banded chromosomes of these three species. Sixteen autosomal probes (i.e. 6-10, 12-22) of the Chinese muntjac each delineated one pair of conserved segments in the forest musk deer and gayal, respectively. The remaining six autosomal probes (1-5, and 11) each delineated two to five pairs of conserved segments. In total, the 22 autosomal painting probes of Chinese muntjac delineated 33 and 34 conserved chromosomal segments in the genomes of forest musk deer and gayal, respectively. The combined analysis of comparative chromosome painting and G-band comparison reveals that most interspecific homologous segments show a high degree of conservation in G-banding patterns. Eleven chromosome fissions and five chromosome fusions differentiate the karyotypes of Chinese muntjac and forest musk deer; twelve chromosome fissions and six fusions are required to convert the Chinese muntjac karyotype to that of gayal; one chromosome fission and one fusion separate the forest musk deer and gayal. The musk deer has retained a highly conserved karyotype that closely resembles the proposed ancestral pecoran karyotype but shares none of the rearrangements characteristic for the Cervidae and Bovidae. Our results substantiate that chromosomes 1-5 and 11 of Chinese muntjac originated through exclusive centromere-to-telomere fusions of ancestral acrocentric chromosomes.     

Cervid satellite DNA and karyotypic evolution of Indian muntjac

Five satellite DNA families (designated as satellite I?CV) have been identified in the Cervidae so far. Among those, satellite I, II and IV are centromere specific. Satellite I and II are shared by large number of deer species, where satellite IV is highly conserved among several deer species examined. Satellite III was initially thought to be roe deer specific but later identified in Chinese water deer as well. SatelliteV is Y-chromosome specific for several Asian deer species examined but also found in the pericentric region of Indian muntjac chromosome 3 and in X chromosome of Chinese water deer. The observation of interstitial hybridization sites on Indian muntjac chromosomes with satellite DNA I probe generated from Chinese muntjac provides the first molecular evidence supporting the tandem fusion theory that 2n=6??/7??of Indian muntjac karyotype could derive from an ancestral Chinese muntjac-like species with 2n=46. Interspecies chromosome painting study and the maximum number of interstitial hybridization detected with satellite I and satellite II DNA probes lend support to the hypothesis that the Indian muntjac karyotype could evolve directly from an ancestral Chinese water deer-like species with 2n=70. Such hypothesis is further substantiated by the finding of satellite V signals presented in specific chromosome regions between the Chinese water deer and the Indian muntjac chromosomes.     

A simple statistical analysis of Indian muntjac Giemsa band patterns.

Indian Muntiacus muntjac G-banded chromosomes were used for computerized analysis for standardized karyotype generation. Individual chromosomes on high-contrast photographic negatives were scanned densitometrically. Alignment of each chromosome for analysis was achieved by locating predominant peaks as well as the centromere. This provided better alignment that the use of the chromosome-end locations. The standardized set was obtained by determing the root-mean-square average density along 10-20 homologous chromosomes. The resulting standard karyotype differs from those published earlier. Prophase chromosomes exhibited greater detail than more condensed metaphase chromosomes. Although Indian muntjac chromosomes were used as a model, the method of analysis should be readily adaptable for examining chromosomes of any origin. The analytic technique should be within the capabilities of the smallest cytogenetic laboratories.