Entamoeba histolytica: alterations in EhRabB protein in a phagocytosis deficient mutant correlate with the Entamoeba dispar RabB sequence

We analyzed the expression and location of EhRabB in clone L-6, a phagocytosis-deficient mutant of Entamoeba histolytica, in comparison with the wild-type clone A. Intriguingly, trophozoites of clone L-6 express more EhRabB than those of clone A. However, the majority of EhRabB-containing vesicles remained in the cytoplasm of clone L-6 during phagocytosis. To investigate molecular alterations in EhRabB of clone L-6 we compared the EhrabB gene sequences from clones L-6 and A. We also isolated, sequenced and compared the RabB protein of Entamoeba dispar. Results showed that EhrabB gene of clone L-6 is 98.2 and 94.1% identical to rabB genes of E. dispar and clone A, respectively. The rabB genes from clone A and E. dispar have 92.2% identity. Four out of five amino acids changes in RabB proteins of clone L-6 and E. dispar are shared. These changes may alter the binding of effector proteins and the specific subcellular location of EhRabB.     

异育银鲫A+系和F系肌间骨的比较分析

研究采用常规测量法和解剖法, 并结合CT透视, 比较分析了异育银鲫主养品种“中科3号”(A+系)和候选新品系F系的肌间骨的数目、形态和分布。结果表明, 6月龄和18月龄异育银鲫F系平均总肌间骨数分别为71.8±2.9和83.3±1.4, 均极显著少于相应月龄银鲫A+系总肌间骨数目(78.6±3.9和87.0±1.5)(P<0.01)。并统计了2个品系的每一肌节的平均肌间骨数目, 6月龄和18月龄异育银鲫F系的每一肌节的平均肌间骨数目极显著少于相应月龄银鲫A+系(P<0.01)。银鲫A+系和F系均有髓弓小骨和脉弓小骨, 没有椎体小骨。6月龄和18月龄银鲫F系髓弓小骨的平均数目为48.2±1.1和55.8±0.52, 均极显著少于相应月龄银鲫A+系的髓弓小骨(53.7±1.6和58.7±0.5)(P<0.01)。异育银鲫两个品系的脉弓小骨数目差异不显著; 2个品系均具有“I”形、“卜”形、“Y”形、一端多叉形、两端两分叉形、两端多叉形和树枝形7种类型的肌间骨, 髓弓小骨比脉弓小骨数量多且形状复杂。随着月龄的增长, 2个品系具有的总肌间骨数目以及复杂肌间骨数目均增加。6月龄和18月龄银鲫F系躯轴上肌节间的复杂“Y”形髓弓小骨数目均比相应月龄的银鲫A+系少, 而简单的“I”形髓弓小骨数目比相应月龄的A+系多, 表现出一种有利于食用的优势。研究结果为异育银鲫候选新品系F系提供了一个品质评价指标, 同时也为后续进行异育银鲫肌间骨遗传改良提供了形态学基础资料。     

Clonal variants of a melanoma cell line sensitive to growth inhibition by dexamethasone

We have isolated and characterized two clones of the RPMI 3460 Syrian hamster melanoma cell line which exhibit different responses to the synthetic glucocorticoid dexamethasone. In the presence of 10 nM dexamethasone, one clone (clone 6) exhibits the growth inhibition, morphological alterations, and reduction in final cell density observed in the parental RPMI 3460 cell line. In contrast, the other clone (clone 5), although exhibiting a reduction in final cell density, fails to exhibit the growth inhibition and morphological alterations. Thus, the effect of dexamethasone on growth and morphology can be expressed separately from the effect of dexamethasone on final cell density in these cells. This observation suggests that the two sets of responses can be controlled separately and that glucocorticoids may exert their influence through different or divergent biological pathways.In vitro receptor assays suggest that the different phenotypes of clone 5 compared with clone 6 cells cannot be explained by an absence of or reduction in cytosolic glucocorticoid receptor, in clone 5 cells. Additional receptor characterization suggests that the different responses to dexamethasone of clone 5 and clone 6 cells do not reflect changes in the ability of receptor to exist in a stably activated form. Differences in the accumulation or depletion of extracellular components in the growth medium also do not seem to be responsible for the altered phenotype of clone 5 vis-à-vis clone 6 cells.     

Heteroduplex analysis of the RNA of clone 3 Moloney murine sarcoma virus.

Heteroduplex analysis of the RNA isolated from purified virions of clone 3 Moloney murine sarcoma virus (M-MSV) hybridized to cDNA's from Moloney murine leukemia virus (M-MLV) and clone 124 M-MSV shows that the main physical component of clone 3 RNA is missing all or most of the 1.5-kilobase (kb) clone 124 M-MSV specific sequence denoted beta s (S. Hu et al. Cell 10:469--477, 1977). This sequence is either deleted in clone 3 RNA or substituted by a very short (0.3-kilobase) sequence. In other respects, clone 3 and clone 124 RNAs show the same heteroduplex structure relative to M-MLV. Since beta s is believed to contain the src gene(s) of clone 124 RNA, this result leaves as an unresolved question the nature of the src gene(s) of the clone 3 M-MSV RNA complex.     

The highly leukotoxic JP2 clone of Aggregatibacter actinomycetemcomitans: evolutionary aspects, epidemiology and etiological role in aggressive periodontitis

For many years, attention has been given to the oral bacterium Aggregatibacter actinomycetemcomitans, as a species possibly implicated in the etiology of aggressive periodontitis in adolescents. One of the major virulence factors of A. actinomycetemcomitans is the leukotoxin which is able to kill important cells of the immune system. As demonstrated in population genetic analyses, the population structure of A. actinomycetemcomitans is mainly clonal with evolutionary lineages corresponding to the serotypes. A particular highly leukotoxic clone (JP2) of serotype b has been discovered. The JP2 clone, with an estimated origin some 2400 years ago, is found to be highly conserved, based on analyses of a collection of JP2 clone strains collected through more than 20 years from individuals of diverse origin and living geographically widespread. Despite demonstration of minor evolutionary changes within the genome of JP2 clone strains of A. actinomycetemcomitans, the JP2 clone strains constitute a unique clonal type, the characteristics of which include a 530 basepair deletion in the leukotoxin operon implicated in the enhanced leukotoxic activity of the clone. Mapping of the geographic occurrence of the JP2 clone of A. actinomycetemcomitans has revealed that its colonization is largely restricted to individuals of African descent. Characteristic mutations, which allow JP2 clone isolates from the Mediterranean region to be distinguished from isolates from West Africa, including the Cape Verde islands, suggest that the JP2 clone initially emerged as a distinct genotype in the Mediterranean region of Africa and subsequently spread to West Africa, from where it might have been transferred to the American continent during the transatlantic slave trade. The finding of a sustained selective colonization of individuals of African descent, despite geographical separation from the African continent for centuries, suggests that the JP2 clone might have a distinct host tropism. Further studies are needed to elucidate the reasons for the apparent selective colonization of the Mediterranean and Western African populations. The JP2 clone of A. actinomycetemcomitans appears to play a prominent role in the etiology of aggressive periodontitis compared to other clonal types of the species. While A. actinomycetemcomitans, in general, is considered an opportunistic pathogen of the resident oral microbiota, the JP2 clone has features similar to those of an exogenous pathogen. Clonal types other than JP2 can be isolated from healthy as well as periodontally diseased individuals, whereas the JP2 clone has been isolated primarily from periodontally diseased individuals. As demonstrated in a prospective cohort study in Morocco, where the JP2 clone is endemically present, the presence of this clone in dental plaque confers a remarkably increased risk for development of aggressive periodontitis, suggesting that the JP2 clone is an important etiological agent of aggressive periodontitis in adolescents. Support for association of clonal types other than JP2 of A. actinomycetemcomitans with aggressive periodontitis has also been provided, but the association is much weaker. Nearly half of the JP2 clone carriers were found to be persistently infected during a two-year follow-up period, which indicates a level of stability of colonization with the JP2 clone similar to that previously reported for non-JP2 clonal types of A. actinomycetemcomitans. The relative risk of aggressive periodontitis is highest for individuals with stable JP2 clone colonization. Although the method used is not quantitative, this finding adds to the evidence for a causal role of the JP2 clone in aggressive periodontitis. Longitudinal data shows that few individuals are colonized with the JP2 clone de novo after puberty. Patterns of parent-child carriage and shared colonization of JP2 clone strains among siblings have been demonstrated in other studies, altogether indicating that transmission of the JP2 clone, like other clonal types of A. actinomycetemcomitans, occurs vertically, and through close person to person contacts. In conclusion, a conserved and highly leukotoxic clone of A. actinomycetemcomitans with unique characteristics and with an apparent linkage to individuals of African descent has been identified. Being aware that the genetic constitution of the hosts has not been considered and that focus in our studies has been on A. actinomycetemcomitans only, and not on other members of the oral microbiota, we conclude that the JP2 clone of A. actinomycetemcomitans is a likely etiological agent of aggressive periodontitis in adolescents.     

Hormonal Regulation of Gametangial Formation in the Moss Bryum argenteum Hedw

Phytohormones such as auxins, cytokinins, gibberellins, andabscisic acid differentially affect gametangial induction inmale and female clones of Bryum argenteum. Both IAA and GA³increased the percentage of fertile gametophores in the maleclone, and inhibited the response in the female clone. GA₃ wasmore effective than IAA in eliciting the response in the maleclone. Cytokinins, on the other hand, increased the productionof fertile gametophores in the female clone, and inhibited itslightly in the male clone. The two cytokinins tested (kinetinand DMAAP) were almost equally effective for the female clone. An Interaction of IAA and kinetin nullified their individualinhibitory effects on the female and male clones, respectively.Cyclic AMP prevented the inhibitory effect of kinetin in themale clone; whereas, in the female clone, it stimulated theresponse elicited by kinetin. Abscisic acid (ABA) acted as ageneral inhibitor of vegetative growth and gametangial inductionin this moss. However, the inhibition of gametangial inductionwas greater in the female clone which is also more sensitiveto ABA than the male clone.     

高产人参寡糖素培养细胞克隆系的筛选

人参（ＰａｎａｘｇｉｎｓｅｎｇＣ．Ａ．Ｍｅｙ．）培养细胞经细胞平板克隆,获得近３００个克隆系。克隆系在细胞生长速率和寡糖素含量及产率上均存在显著差异,且寡糖素产率和细胞生长之间有明显的相关性。经１１代连续继代培养观察及过氧化物酶同工酶谱特征分析,筛选到一株寡糖素产率高且稳定的克隆系ＰＧ－１８０,其平均生长速率是０．４９５ｇ于重／Ｌ·天,为原始株系的１．３９倍,平均寡糖素含量为１４．６９％干重,是亲本的１．６５倍,平均寡糖素产率是２．１８３ｇ／Ｌ,为原始株系的２．３２倍。比较克隆系ＰＧ－１８０和原始株系细胞悬浮培养时间进程发现,由人参培养细胞生产寡糖素的最佳细胞收获期为３周左右。     

A genomic clone of Zfy-1 from a YDOM mouse strain detects post-meiotic gene expression of Zfy in testes

In order to obtain a genomic clone of Zfy-1 from a Y chromosome of Mus musculus domesticus (YDOM) origin, we cloned size-fractionated SJL/J DNA in EMBL-4 and selected colonies which hybridized to pDP1007, a human zinc finger Y clone. The specificity of the clone in hybridizations to mouse and human DNA and partial sequencing confirmed that the clone (subcloned as pGZfy1D) was of Zfy-1 origin. Studies on the expression during testicular development of mRNAs hybridizing to the clone suggested that the gene is expressed post-meiotically.     

Screening of Clone Lines with High Yield of Oligosaccharins from Culture Cells of Panax ginseng

Cell plating clone technique was employed to screen clone lines with high yield of oligosaccharins from culture cells of Panax ginseng C. A. Mey. Near 300 clone lines were obtained. The results from some clone lines analysed implied that these clone lines were significantly different in cell growth rate, oligosaccharins content and yield. Furthermore, there was a distinct correlation between oligosaccharins productivity and cell growth. A more stable high-yield oligosaccharin clone line PG-180 had been selected according to the characteristics of growth rate, oligosaccharin yield and peroxidases isozyme patterns during successive subculturing of 11 generations of clone lines. The mean growth rate of clone line PG-180 was 0. 495 g dry wt/L · d, and was 1.39 folds higher than to the original strain. Its mean content and yield of oligosaccharins were 14. 69 % dry wt and 2.183 g/L, which were 65 % and 132% respectively higher than those of the original strain. In comparing the time course of cell suspension culture between clone line PG-180 and the original strain, the optimal period for high oligosaccharin production from P. ginseng culture cells was approximately three weeks.     

Community composition of marine bacterioplankton determined by 16S rRNA gene clone libraries and fluorescence in situ hybridization

We determined the compositions of bacterioplankton communities in surface waters of coastal California using clone libraries of 16S rRNA genes and fluorescence in situ hybridization (FISH) in order to compare the community structures inferred from these two culture-independent approaches. The compositions of two clone libraries were quite similar to those of clone libraries of marine bacterioplankton examined by previous studies. Clones from gamma-proteobacteria comprised ca. 28% of the libraries, while approximately 55% of the clones came from alpha-proteobacteria, which dominated the clone libraries. The Cytophaga-Flavobacter group and three others each comprised 10% or fewer of the clone libraries. The community composition determined by FISH differed substantially from the composition implied by the clone libraries. The Cytophaga-Flavobacter group dominated 8 of the 11 communities assayed by FISH, including the two communities assayed using clone libraries. On average only 10% of DAPI (4', 6'-diamidino-2-phenylindole)-stained bacteria were detected by FISH with a probe for alpha-proteobacteria, but 30% of DAPI-stained bacteria appeared to be in the Cytophaga-Flavobacter group as determined by FISH. alpha-Proteobacteria were greatly overrepresented in clone libraries compared to their relative abundance determined by FISH, while the Cytophaga-Flavobacter group was underrepresented in clone libraries. Our data show that the Cytophaga-Flavobacter group can be a numerically dominant component of coastal marine bacterioplankton communities.     

Increase of MnSOD expression and decrease of JNK activity determine the TNF sensitivity in bcl2-transfected L929 cells.

To investigate the protection mechanism of Bcl-2 against tumour necrosis factor (TNF)-mediated cell death, the bcl2 gene was transfected into the L929 cells and stably expressed. Two clones having different sensitivity among bcl2-transfected L929 clones had been isolated, and termed clone R1 and R2. It was observed that activation of manganese superoxide dismutase (MnSOD) and suppression of Jun kinase of clone R1 and R2 were correlated with protection from TNF cytotoxicity. Upon treatment with TNF, clone R1 and R2 were more resistant than control L929 cells against TNF cytotoxicity and the protective effect of clone R1 was stronger than clone R2. However, in case of TNF plus actinomycin D treatment, clone R1 was still resistant against TNF cytotoxicity, whereas clone R2 became more sensitive than control L929 cells. The JNK activities of clone R1 and R2 were suppressed upon TNF treatment and in case of TNF plus actinomycin D treatment, clone R2 showed a marked increase in JNK activities and had higher activity than control L929 cells. The specific activities of MnSOD of clone R1 and R2 upon TNF treatment were 70 U/ml and 33 U/ml, respectively, while the MnSOD activity was not detectable in control L929 cells. When TNF and actinomycin D were treated simultaneously, MnSOD activity was not detectable in control L929 cells and bcl2 -transfected L929 cells (clone R1, R2). Consistent with these results, both clone R1 and R2 showed higher levels of MnSOD mRNA expression than control L929 cells after TNF treatment. These data suggest that suppression of Jun kinase and increase of MnSOD may be involved in inhibitory action of Bcl-2 against TNF, and the balance between MnSOD and JNK signalling pathway may be an important factor for the protection of bcl2-transfected L929 cells from TNF cytotoxicity.     

A MONTE CARLO SIMULATION OF CLONE GROWTH

A Monte Carlo simulation of clone growth is discussed from the point of view of clonal volume. It is shown that clone volume is a good representation of the number of cells per clone for a wide range of single cell growth equations. However, the rate at which the coefficient of variation in clonal volume approaches that of cell number per clone is strongly dependent upon the particular growth equation.     

Isolation and chromosomal localization of a novel nonerythroid ankyrin gene.

Immunoreactive isoforms of erythrocyte ankyrin have been shown to be present in a variety of nonerythroid tissues. Isolation of the genes that encode these isoforms will clarify their relationship to erythrocyte ankyrin. Using an erythrocyte ankyrin cDNA clone as a hybridization probe, we screened a human genomic library and isolated a clone that hybridizes with the probe at low stringency but not at high stringency. Partial nucleotide sequence of the clone revealed the presence of a 99-bp segment that is homologous to an exon of the erythrocyte ankyrin gene. Northern analysis showed that a labeled fragment of the clone hybridized to a 7-kb message in RNA of fetal brain but not of erythroid cells, suggesting that this clone is part of a novel gene that is expressed predominantly in nonerythroid tissue. Comparison of the sequence of the genomic clone with that of a recently isolated cDNA clone for brain ankyrin (Otto et al., 1989) showed identity of 96 of 99 bp between the putative exon and a segment of the cDNA clone (V. Bennett, personal communication, 1991), suggesting that the genomic clone is part of a gene for nonerythroid ankyrin, which we have designated ANK2. By analysis of somatic cell hybrids and fluorescence in situ hybridization, we assigned ANK2 to human chromosome 4 at a position equivalent to bands 4q25-q27.     

Diversity of nitrite reductase genes in "Candidatus Accumulibacter phosphatis"-dominated cultures enriched by flow-cytometric sorting

"Candidatus Accumulibacter phosphatis" is considered a polyphosphate-accumulating organism (PAO) though it has not been isolated yet. To reveal the denitrification ability of this organism, we first concentrated this organism by flow cytometric sorting following fluorescence in situ hybridization (FISH) using specific probes for this organism. The purity of the target cells was about 97% of total cell count in the sorted sample. The PCR amplification of the nitrite reductase genes (nirK and nirS) from unsorted and sorted cells was performed. Although nirK and nirS were amplified from unsorted cells, only nirS was detected from sorted cells, indicating that "Ca. Accumulibacter phosphatis" has nirS. Furthermore, nirS fragments were cloned from unsorted (Ba clone library) and sorted (Bd clone library) cells and classified by restriction fragment length polymorphism analysis. The most dominant clone in clone library Ba, which represented 62% of the total number of clones, was not found in clone library Bd. In contrast, the most dominant clone in clone library Bd, which represented 59% of the total number of clones, represented only 2% of the total number of clones in clone library Ba, indicating that this clone could be that of "Ca. Accumulibacter phosphatis." The sequence of this nirS clone exhibited less than 90% similarity to the sequences of known denitrifying bacteria in the database. The recovery of the nirS genes makes it likely that "Ca. Accumulibacter phosphatis" behaves as a denitrifying PAO capable of utilizing nitrite instead of oxygen as an electron acceptor for phosphorus uptake.     

Can clone size serve as a proxy for clone age?An exploration using microsatellite divergence in Populus tremuloides

In long‐lived clonal plants, the overall size of a clone is often used to estimate clone age. The size of a clone, however, might be largely determined by physical or biotic interactions, obscuring the relationship between clone size and age. Here, we use the accumulation of mutations at 14 microsatellite loci to estimate clone age in trembling aspen (Populus tremuloides) from southwestern Canada. We show that the observed patterns of genetic divergence are consistent with a model of increasing ramet population size, allowing us to use pairwise genetic divergence as an estimator of clone age. In the populations studied, clone size did not exhibit a significant relationship with microsatellite divergence, indicating that clone size is not a good proxy for clone age. In P. tremuloides, the per‐locus per‐year neutral somatic mutation rate across 14 microsatellite loci was estimated to lie between 6 × 10^?7 (lower bound) and 4 × 10^?5 (upper bound).     

Effects of tert-butyl hydroperoxide on promotable and non-promotable JB6 mouse epidermal cells

Oxidants and agents that induce a cellular prooxidant state can act as carcinogens. We compared the effect of tert-butyl hydroperoxide (Bu-OOH) on DNA strand breakage, poly ADP-ribosylation of chromosomal proteins and the expression of the proto-oncogenes c-fos and c-myc between non-promotable clone 30 and promotable clone 41 of mouse epidermal cells JB6. These pathophysiological effects of oxidants are mechanistically related. Bu--OOH caused more DNA-strand breakage at high concentrations and more extensive poly ADP-ribose accumulation in clone 30 than in clone 41, in reactions which require intracellular free iron. Clone 41 exhibited constitutive c-myc expression while c-fos mRNA was very low in untreated cultures of both clones. Low concentrations of Bu-OOH induced c-myc and more strongly c-fos in clone 41. Both proto-oncogenes were strongly induced in clone 30. Our results allow insights into the mechanisms of action of a typical organic hydroperoxide in JB6 cells. However, they do not uncover the reasons for the differential promotability of the two JB6 clones by oxidants beyond the implication of the constitutive expression of c-myc in promotable clone 41.     

Plasmodium berghei: in vivo generation and selection of karyotype mutants and non-gametocyte producer mutants.

We previously reported that karyotype and gametocyte-producer mutants spontaneously arose during in vivo asexual multiplication of Plasmodium berghei. Here we studied the rate of selection of these mutants in vivo. Gametocyte production and karyotype pattern were established at regular intervals during prolonged periods of asexual multiplication of clone 8417 of P. berghei. We found that karyotype mutants and mutants which do not produce gametocytes can replace the original high-producer parasites of clone 8417 within several weeks. The time at which mutants became predominant in the population in different experiments, however, differed greatly. Mutants with intermediate or low gametocyte production were not found. In experimentally mixed infections, containing parasites from two clones from different strains (clone 8417 of the ANKA strain; clone 1 of the K173 strain), high-producer parasites of clone 8417 were overgrown by parasites of the nonproducer clone. Nonproducer mutants from the originally high-producer clone 8417, however, were able to coexist with parasites of the nonproducer clone. These results demonstrate that in our experiments nonproducer parasites had a strong selective advantage during asexual multiplication compared to high producers. All karyotype mutants which became predominant in our experiments were nonproducers. In two experiments a change in karyotype coincided with the loss of gametocyte production which may suggest a causal relationship between these events.     

Survival of the mutant clone. III. Catastrophic selection. The inadequacy of the selection coefficient for assessing clone fate]

Majorant estimations of the probabilities pr for the surviving of the clone of the dividing cells have been obtained in the catastrophic situation (monotonous diminishing of the clone almost to zero during the period of time from t=0 to t=T, T approximately 100 generation). At t=0 the clone consisted of 10(6) individuals. Average selection coefficient (s) was found to determine pr only roughly, that is the clone with s greater than --0.09 survives almost in all cases, whereas the clone with s greater than --0.13 becomes extinct practically always. Within this interval ps-inversion can be observed, i.e. preferential surviving of the clone with a worse s value. Results of three communications lead to the conclusion that the mutants with small selective advantage practically cannot be selected.     

The plant activation of m-phenylenediamine by Tradescantia clone 03 and clone 4430 cells in liquid suspension culture

In this study, we expanded the use of the genus Tradescantia to investigate the plant activation of promutagens and further refine the methodology of the plant cell/microbe coincubation assay. Liquid suspension cell cultures of Tradescantia clone 03 and Tradescantia clone 4430 were used to activate the promutagen m-phenylenediamine into a mutagenic compound which was detected by Salmonella typhimurium strain TA98 in the plant cell/microbe coincubation assay. Optimum treatment parameters were established for both plant cell lines. Optimum was defined as the lowest concentration or shortest time period that provided consistently positive results and high rates of revertants. Preliminary experiments with both cell lines defined 2.5 mumoles m-phenylenediamine per plate as the optimum concentration to be used in the determination of the optimal coincubation period and the optimal concentration of plant cells. These experiments also determined the optimal physiological stage at which both clones should be used in the coincubation assay. Differences were found in the optimal of coincubation (1h for clone 03, 2 h for clone 4430) and growth stage (mid-log for clone 03, mid- to late-log for clone 4430). Similar activation responses were seen for both clones when the concentration of plant cells (mg/ml) was varied. Under optimized conditions, clone 03 cells demonstrated an approximately 10% higher activation response than clone 4430.     

A novel nucleo-cytoplasmic hybrid clone formed via androgenesis in polyploid gibel carp

Background

Unisexual vertebrates have been demonstrated to reproduce by gynogenesis, hybridogenesis, parthenogenesis, or kleptogenesis, however, it is uncertain how the reproduction mode contributes to the clonal diversity. Recently, polyploid gibel carp has been revealed to possess coexisting dual modes of unisexual gynogenesis and sexual reproduction and to have numerous various clones. Using sexual reproduction mating between clone D female and clone A male and subsequent 7 generation multiplying of unisexual gynogenesis, we have created a novel clone strain with more than several hundred millions of individuals. Here, we attempt to identify genetic background of the novel clone and to explore the significant implication for clonal diversity contribution.

Methods

Several nuclear genome markers and one cytoplasmic marker, the mitochondrial genome sequence, were used to identify the genetic organization of the randomly sampled individuals from different generations of the novel clone.

Results

Chromosome number, Cot-1 repetitive DNA banded karyotype, microsatellite patterns, AFLP profiles and transferrin alleles uniformly indicated that nuclear genome of the novel clone is identical to that of clone A, and significantly different from that of clone D. However, the cytoplasmic marker, its complete mtDNA genome sequence, is same to that of clone D, and different from that of clone A.

Conclusions

The present data indicate that the novel clone is a nucleo-cytoplasmic hybrid between the known clones A and D, because it originates from the offspring of gonochoristic sexual reproduction mating between clone D female and clone A male, and contains an entire nuclear genome from the paternal clone A and a mtDNA genome (cytoplasm) from the maternal clone D. It is suggested to arise via androgenesis by a mechanism of ploidy doubling of clone A sperm in clone D ooplasm through inhibiting the first mitotic division. Significantly, the selected nucleo-cytoplasmic hybrid female still maintains its gynogenetic ability. Based on the present and previous findings, we discuss the association of rapid genetic changes and high genetic diversity with various ploidy levels and multiple reproduction modes in several unisexual and sexual complexes of vertebrates and even other invertebrates.