Genome-wide comparative chromosome map between human and the Forrest's pika (Ochotona forresti) established by cross-species chromosome painting: further support for the Glires hypothesis

Comparative genomic data for ochotonids (pikas) are important for understanding the karyotype evolution of lagomorphs. Here, we have established the first genome-wide chromosomal homologies between human and the Forrest's pika (Ochotona forresti, 2n = 54) by cross-species chromosome painting. Integration of our map with the published comparative chromosome map between human and rabbit has enabled the establishment of an indirect homology map between Forrest's pika and domestic rabbit (Oryctolagus cuniculus, 2n = 44), representing the 2 Lagomorpha families: Leporidae and Ochotonidae. Our results demonstrate that (1) most of the proposed ancestral eutherian syntenies or syntenic associations have been retained in the O. forresti genome; (2) the HSA1/10p association, one of the 2 signature rearrangements that were proposed to support the grouping of the orders Lagomorpha and Rodentia into a monophyletic clade called Glires, is also present in the O. forresti genome; and (3) Robertsonian translocations have contributed to the karyotype differences between O. forresti and O. cuniculus.

Karyotype evolution of giraffes (Giraffa camelopardalis) revealed by cross-species chromosome painting with Chinese muntjac (Muntiacus reevesi) and human (Homo sapiens) paints

Considering the giraffe (Giraffa camelopardalis, GCA, 2n = 30) as a primitive species, its comparative genomic data are critical for our understanding of the karyotype evolution of pecorans. Here, we have established genome-wide chromosomal homologies between giraffe, Chinese muntjac (Muntiacus reevesi, MRE, 2n = 46) and human (Homo sapiens, HSA, 2n = 46) with whole sets of chromosome-specific paints from Chinese muntjac and human, in addition to providing a high-resolution G-banding karyotype of giraffe. Chinese muntjac and human chromosome paints detected 32 and 45 autosomal homologs in the genome of giraffe, respectively. Our results suggest that it would require at least thirteen fissions, six fusions and three intrachromosomal rearrangements to 'transform' the 2n = 44 eutherian ancestral karyotype to the 2n = 58 pecoran ancestral karyotype. During giraffe evolution, some ancestral eutherian syntenies (i.e. association of HSA3/21, 4/8, 7/16, 14/15, 16/19 and two forms of 12/22) have been retained, while several derived syntenies (i.e. associations of human homologous segments 2/1, 2/9, 5/19, 4/12/22, 8/9, and 10/20) have been produced. The reduction of chromosome number in giraffe from the 2n = 58 pecoran ancestral karyotype could be primarily attributed to extensive Robertsonian translocations of ancestral chromosomal segments. More complex chromosomal rearrangements (including tandem fusion, centromere repositioning and pericentric inversion) have happened during the evolution of GCA2 and GCA8.

Karyotype relationships of six bat species (Chiroptera, Vespertilionidae) from China revealed by chromosome painting and G-banding comparison

The Vespertilionidae is the largest family in the order Chiroptera and has a worldwide distribution in the temperate and tropical regions. In order to further clarify the karyotype relationships at the lower taxonomic level in Vespertilionidae, genome-wide comparative maps have been constructed between Myotis myotis (MMY, 2n = 44) and six vesper bats from China: Myotis altarium (MAL, 2n = 44), Hypsugo pulveratus (HPU, 2n = 44), Nyctalus velutinus (NVE, 2n = 36), Tylonycteris robustula (TRO, 2n = 32), Tylonycteris sp. (TSP, 2n = 30)and Miniopterus fuliginosus (MFU, 2n = 46) by cross-species chromosome painting with a set of painting probes derived from flow-sorted chromosomes of Myotis myotis. Each Myotis myotis autosomal probe detected a single homologous chromosomal segment in the genomes of these six vesper bats except for MMY chromosome 3/4 paint which hybridized onto two chromosomes in the genome of M. fuliginosus. Our results show that Robertsonian translocation is the main mode of karyotype evolution in Vespertilionidae and that the addition of heterochromatic material also plays an important role in the karyotypic evolution of the genera Tylonycteris and Nyctalus. Two conserved syntenic associations (MMY9 + 23 and 18 + 19) could be the synapomorphic features for the genus Tylonycteris. The integration of our maps with the published maps has enabled us to deduce chromosomal homologies between human and these six vesper bats and provided new insight into the karyotype evolution of the family Vespertilionidae.

Tandem chromosome fusions in karyotypic evolution of Muntiacus: evidence from M. feae and M. gongshanensis

The muntjacs (Muntiacus, Cervidae) are famous for their rapid and radical karyotypic diversification via repeated tandem chromosome fusions, constituting a paradigm for the studies of karyotypic evolution. Of the five muntjac species with defined karyotypes, three species (i.e. Muntiacus reevesi, 2n = 46; M. m. vaginalis, 2n = 6/7; and M. crinifrons, 2n = 8/9) have so far been investigated by a combined approach of comparative chromosome banding, chromosome painting and BAC mapping. The results demonstrated that extensive centromere-telomere fusions and a few centric fusions are the chromosomal mechanisms underlying the karyotypic evolution of muntjacs. Here we have applied the same approach to two additional muntjac species with less well-characterized karyotypes, M. feae (2n = 14 male ) and M. gongshanensis (2n = 8 female). High-resolution G-banded karyotypes for M. feae and M. gongshanensis are provided. The integrated analysis of hybridization results led to the establishment of a high-resolution comparative map between M. reevesi, M. feae, and M. gongshanensis, proving that all tandem fusions underpinning the karyotypic evolution of these two muntjac species are also centromere-telomere fusions. Furthermore, the results have improved our understanding of the karyotypic relationships of extant muntjac species and provided compelling cytogenetic evidence that supports the view that M. crinifrons, M. feae, and M. gongshanensis should each be treated as a distinct species.

Karyotypic evolution of the family Sciuridae: inferences from the genome organizations of ground squirrels

Cross-species chromosome painting has made a great contribution to our understanding of the evolution of karyotypes and genome organizations of mammals. Several recent papers of comparative painting between tree and flying squirrels have shed some light on the evolution of the family Sciuridae and the order Rodentia. In the present study we have extended the comparative painting to the Himalayan marmot (Marmotahimalayana) and the African ground squirrel (Xerus cf. erythropus), i.e. representative species from another important squirrel group--the ground squirrels--, and have established genome-wide comparative chromosome maps between human, eastern gray squirrel, and these two ground squirrels. The results show that 1) the squirrels so far studied all have conserved karyotypes that resemble the ancestral karyotype of the order Rodentia; 2) the African ground squirrels could have retained the ancestral karyotype of the family Sciuridae. Furthermore, we have mapped the evolutionary rearrangements onto a molecular-based consensus phylogenetic tree of the family Sciuridae.

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.

Karyotypic conservatism in the suborder Feliformia (Order Carnivora)

Multidirectional comparative chromosome painting was used to investigate the karyotypic relationships among representative species from three Feliformia families of the order Carnivora (Viverridae, Hyaenidae and Felidae). Complete sets of painting probes derived from flow-sorted chromosomes of the domestic dog, American mink, and human were hybridized onto metaphases of the spotted hyena (Crocuta crocuta, 2n = 40) and masked palm civet (Paguma larvata, 2n = 44). Extensive chromosomal conservation is evident in these two species when compared with the cat karyotype, and only a few events of chromosome fusion, fission and inversion differentiate the karyotypes of these Feliformia species. The comparative chromosome painting data have enabled the integration of the hyena and palm civet chromosomes into the previously established comparative map among the domestic cat, domestic dog, American mink and human and improved our understanding on the karyotype phylogeny of Feliformia species.

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.

Enhanced intracellular glutathione synthesis and excretion capability of Candida utilis by using a low pH-stress strategy

AIMS

To study the effect of low pH stress on glutathione (GSH) synthesis and excretion capability of GSH fermentation production in Candida utilis.

METHODS AND RESULTS

When C. utilis WSH 02-08 was cultivated in a glucose-ammonium sulfate medium without pH control, GSH leakage occurred when the pH of the medium decreased to 1.5. However, analysis of the cell viability indicated that the cells were not lysed. To further study the effect of low pH stress on GSH production, pH-controlled batch cultures were conducted, where the pH was switched from 5.5 to 1.2 at 24 h and maintained at 1.2 for 6 h. Nearly all intracellular GSH was leaked into the medium and the cell viability decreased dramatically, conceiving a long-term exposure of strain WSH 02-08 at low pH environment led to a complete cell lysis. A critical point (treated at pH 1.2 for 3 h) was experimentally determined, where most cells were alive but suffering a low pH stress. Low pH-stressed C. utilis cells displayed an increased intracellular GSH synthesis and export capability, which protected the cells against short-term low pH treatment.

CONCLUSIONS

Using this knowledge, a low pH-stress strategy was developed and applied in fed-batch production of GSH and 197.3 mg l-1 of GSH was secreted into the medium. The GSH-specific production yield could be increased from 2.11 to 2.67% (w/w), and the total GSH concentration could reach 737.1 mg l-1 and increased by 24.9%.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of GSH secretion of C. utilis at low pH. This study demonstrated the importance of the physiology-based fermentation strategy in the production of useful metabolites.

[Observation on the factors influencing infection rate of Meriones unguiculatus with Brugia malayi]

AIM

To explore the factors influencing the infection rate of M. unguiculatus with B. malayi.

METHODS

The survival rate, infection rate and infection intensity were observed in M. unguiculatus infected with the infective larvae of B. malayi contained in normal saline, antibiotic, glucose or culture medium RPMI1640, respectively.

RESULTS

The survival rate, infection rate and rate of infection intensity in normal saline group, antibiotic group, glucose group and RPMI1640 group were 80.9%, 60.5%, and 43.4%; 98.8%, 52.9% and 30.6%; 98.0%, 68.8% and 50.0%; 91.2%, 67.7% and 51.6%, respectively. The rate and the infection intensity were higher in the jirds infected with the 6th generation of Zhejiang strain than that with the 31st generation of Guizhou strain.

CONCLUSION

The antibiotic was found to raise the living rate of the infected jirds, but reduce the infection rate and infection degree intensity; whereas glucose and culture medium RPMI1640 could raise the positive rate and the infectino. The jird was more susceptible to the 6th generation of Zhejiang strain than the 31st generation of Guizhou strain of B. malayi.

[Observation on the susceptibility of Anopheles sinensis to periodic Brugia malayi microfilariae]

AIM

To explore the susceptibility of Anopheles sinensis to Brugia malayi microfilariae of different densities.

METHODS

The survival rate of mosquitoes, the rate of microfilariae penetrating through midgut, the mature rate of larvae into infective larvae (L3) and the mean number of L3 in the survived mosquitoes were observed.

RESULTS

With the microfilariae densities of 32.5 mf/microliter and 141.5 mf/microliter, the rate of larvae matured into L3 was 36.2% and 8.7%, respectively, the mean number of L3 recovered from infected mosquitoes was 8.24 and 0.30, respectively.

CONCLUSION

An apparently higher susceptibility of An. sinensis to B. malayi was found by using B. malayi microfilariae density of 32.5-66.4 mf/microliter.

Correlation between mitochondrial membrane potential and neurotoxic effect of corticosterone on primary cultured hippocampal cells

Experiments were carried out to study the toxic effect of corticosterone (CORT) on primary cultured hippocampal cells and its relationship with mitochondrial membrane potential (MMP). Hippocampal cell survival and MMP were assessed by MTT and laser scanning confocal microscopy respectively. The results indicated that the survival rate of hippocampal neurons and astrocytes was dose dependently reduced in the hypoglycemic (3 5 mmol/L) and serum free medium for 24 h. With the same concentration of CORT, the toxic effect of CORT on hippocampal neurons was more serious than that on astrocytes. A supplement of high concentration of glucose (25 mmol/L) greatly improved the survival rate of hippocampal neurons cultured in the hypoglycemic and serum free medium. The disruption of MMP was induced by CORT (10( 6) mol/L) in hippocampal neurons cultured in hypoglycemic and serum free medium and antagonized by high concentration of glucose. It is therefore suggested that hippocampal neurons are more sensitive to the toxic effect of CORT in comparison with astrocytes. Neurotoxic effect of CORT can be reduced by high concentration of glucose. CORT-induced reduction of MMP may be one of the mechanisms for its neurotoxicity.

Conserved chromosome segments in Hylobates hoolock revealed by human and H. leucogenys paint probes

A complete comparative chromosome map of the white-browed gibbon (Hylobates hoolock, 2n = 38), white-cheeked gibbon (Hylobates leucogenys, 2n = 52), and human has been established by hybridising H. leucogenys chromosome-specific paints and human 24-colour paints onto H. hoolock metaphase chromosomes. In the 18 H. hoolock autosomes, we identified 62 conserved segments that showed DNA homology to regions of the 25 H. leucogenys autosomes. Numerous interchromosomal rearrangements differentiate the karyotypes of H. leucogenys and H. hoolock. Only H. hoolock chromosome 10 showed homology to one entire autosome of H. leucogenys. The hybridisation of human 24-colour paints not only confirmed most of the chromosome correspondences between human and H. hoolock established previously but also helped to correct five erroneous assignments and revealed three new segments. Our results demonstrate that the karyotypes of the extant gibbons have arisen mainly through extensive translocation events and that the karyotype of H. hoolock more closely resembles the ancestral karyotype of Hylobates, rather than the karyotype of H. leucogenys.

Molecular characterization of Tclabial and the 3' end of the Tribolium homeotic complex

The homeotic selector gene labial is located at the 3' end of the Antennapedia complex (ANTC) and is required for proper head development in Drosophila. We have cloned and characterized the Tribolium ortholog of labial, Tclabial (Tclab). Similar to Drosophila labial, Tclab contains a single large intron upstream of the homeobox. In contrast, Tclab lacks an intron within the homeobox. The Tribolium ortholog of chaoptic, Tcchaoptic, transcribed from the opposite strand, is located immediately downstream of the homeotic complex, and its 3'UTR overlaps that of Tclab by 50 nucleotides. We have also sequenced the 13.5 kb interval between Tclab and maxillopedia (the Tribolium ortholog of Drosophila proboscipedia). In contrast to Drosophila, there is not a cluster of cuticle genes in this region. Finally, we have examined the expression of Tclab transcripts in Tribolium embryos. As previously described for Drosophila and other insects, the expression of Tclab is specific to the intercalary segment.

Implications of the Tribolium Deformed mutant phenotype for the evolution of Hox gene function

Among insects, the genetic regulation of regional identities in the postoral head or gnathal segments (mandibular, maxillary, and labial) is best understood in the fly Drosophila melanogaster. In part, normal gnathal development depends on Deformed (Dfd) and Sex combs reduced (Scr), genes in the split Drosophila homeotic complex. The gnathal segments of Dfd and Scr mutant larvae are abnormal but not homeotically transformed. In the red flour beetle, Tribolium castaneum, we have isolated loss-of-function mutations of the Deformed ortholog. Mutant larvae display a strong transformation of mandibular appendages to antennae. The maxillary appendages, normally composed of an endite and a telopodite, develop only the telopodite in mutant larvae. We previously reported that mutations in the beetle Scr and Antennapedia orthologs cause the labial and thoracic appendages, respectively, to be transformed to antennae. Moreover, a deficiency of most of the beetle homeotic complex causes all gnathal (as well as thoracic and abdominal) segments to develop antennae. These and other observations are consistent with the hypothesis that ancestral insect homeotic gene functions have been modified considerably during the evolution of the highly specialized maggot head. One of the ancestral homeobox genes that arose close to the root of the Eumetazoa appears to have given rise to Dfd, Scr, and the Antennapedia homeobox-class homeotic genes. Evidence from both Tribolium and Drosophila suggests that this ancestral gene served to repress anterior development as well as confer a trunk-specific identity.

[Color Doppler flow imaging study on the changes of collateral circulation between portal-superior vena cava and azygos vein before and after endoscopic ligation of the esophageal varix]

Color Doppler flow imaging (CDFI) was performed in 35 patients with portal hypertension and esophageal varix. Thirty subjects were served as control. After esophageal variceal ligation, CDFI observed that the portal-superior vena cava collateral veins were partialy blocked. The esophageal varices disappeared. The esophageal wall thinned. Diameter of left gastric vein enlarged and blood flow velocity decreased. Azygos diameter was reduced and blood flow velocity was decreased. Although diameter of portal vein was not changed, the blood flow velocity slightly increased. The results suggest that ligation treatment can have the tendency to increase blood flow of liver and stomach, which might aggravate gastric mucosal lesion.

Mapping chromosomal homologies between humans and two langurs (Semnopithecus francoisi and S. phayrei) by chromosome painting

Chromosomal homologies were established between human and two Chinese langurs (Semnopithecus francoisi, 2n = 44, and S. phayrei, 2n = 44) by chromosome painting with chromosome-specific DNA probes of all human chromosomes except the Y. Both langur species showed identical hybridization patterns in addition to similar G-banding patterns. In total, 23 human chromosome-specific probes detected 30 homologous chromosome segments in a haploid langur genome. Except for human chromosomes 1, 2, 6, 16 and 19 probes, which each gave signals on two non-homologous langur chromosomes respectively, all other probes each hybridized to a single chromosome. The results indicate a high degree of conservation of chromosomal synteny between human and these two Chinese langurs. The human chromosome 2 probe painted the entire euchromatic regions of langur chromosomes 14 and 19. Human chromosome 1 probe hybridized to three regions on langur autosomes, one region on langur chromosome 4 and two regions on langur chromosome 5. Human 19 probe hybridized on the same pattern to one region on chromosome 4 and to two regions on langur chromosome 5, where it alternated with the human chromosome 1 probe. Human 6 and 16 probes both hybridized to one region on each of the two langur autosomes 15 and 18. Only two langur chromosomes (12 and 21) were each labelled by probes specific for two whole human chromosomes (14 and 15 and 21 and 22 respectively). Comparison of the hybridization patterns of human painting probes on these two langurs with the data on other Old World primates suggests that reciprocal and Robertsonian translocations as will as inversions could have occurred since the divergence of human and the langurs from a common ancestor. This comparison also indicates that Asian colobines are karyotypically more closely related to each other that to African colobines.

[Guiding-evaluation of immunomodulating activity of the Liuwei Dihuang Decoction during the stepwise fractionation]

OBJECTIVE

To conduct the activity evaluation for immunomodulating components from the Liuwei Dihuang Decoction (LWDHD).

METHODS

Cyclophosphamide (Cy)-treated mice were used as the immunodeficient model and the antibody production response in plaque-forming cell (PFC) assay was employed as the activity-evaluating parameter. Stepwise fractionation was guided by activity-evaluation.

RESULTS

Fr1, the ethanol-soluble fraction, and Fr2, the ethanol insoluble fraction of LWDHD, both significantly improved the antibody production response in Cy-treated mice, in which Fr2 showed stronger activity than that of Fr1. Fr2 was further fractionated. Fr2-CA4, one of the fractions obtained by active carbon chromatography from Fr2, exhibited the strongest activity in comparison with other fractions.

CONCLUSION

CA4, which is mainly composed of acidic polysaccharides, is the main immunomodulating active fraction contained in the ethanol-insoluble fraction of LWDHD.

[Endoscopic variceal ligation combined with partial splenic embolization: preliminary clinical results]

Endoscopic variceal ligation combined with partial splenic embolization (EVL-PSE) was performed in a group of 13 patients with esophageal variceal bleeding and hypersplenism due to portal hypertension from January 1997 to March 1998. PSE was performed one to two weeks before or one week after initial EVL, and a range of 30% to 60% of the splenic parenchyma was embolized. Repeated EVL was performed at two week intervals until the varices were eradicated. Active bleeding in the nine patients was successfully controlled and all the varices of the 13 patients were eradicated after EVL-PSE. Eradication of the varices required two to five(mean 3.1) EVL sessions, follow-up ranging from 2 to 16 months(mean 6.9 months). In all but one case, no rebleeding occurred. All patients after PSE showed a good response on peripheral blood cell count and reduction of splenomegaly. No major complication or death related to the combination therapy was observed. Preliminary results in this study show that this combination therapy may result in more rapid eradication of the varices and reduce rebleeding after endoscopic variceal ligation. However, more data and studies may be necessary for further evaluation.