A novel family of short interspersed repetitive elements (SINEs) from cichlids: the patterns of insertion of SINEs at orthologous loci support the proposed monophyly of four major groups of cichlid fishes in Lake Tanganyika

Short interspersed repetitive elements (SINEs) have been shown to be excellent markers of molecular phylogeny, since the integration of a SINE at a particular position in a genome can be considered an unambiguous derived homologous character. In the present study, we isolated a new family of SINEs from cichlids in Lake Tanganyika, whose speciation and diversification have been regarded as prime examples of explosive adaptive radiation. Members of this new SINE family, which we named the AFC family, are about 320 bp in length, and each has a tRNA- related region in its 5' region, as do most of the members of SINE families reported to date. A dot blot hybridization experiment showed that this family is distributed extensively in the genomes of cichlids in Africa, with estimated copy numbers of 2 x 10(3)-2 x 10(4) per haploid genome. Our investigations of the patterns of insertion of members of this family at six orthologous loci demonstrated clearly that four previously identified tribes, namely, the Lamprologini, Ectodini, Tropheini, and Perissodini, each form a monophyletic group. These results provide a basis for the elucidation of the phylogenetic framework of the cichlid fishes in Lake Tanganyika.      

A lone male chimpanzee in the wild: The survivor of a disintegrated unit-group

K Group, originally one of the two major study groups of chimpanzees since 1965 in the Mahale Mountains National Park, western Tanzania, was almost extinct by 1983: at most seven individuals remained in the group at the beginning of 1983. K Group continued to exist for more than four years, but in 1987 a male was left alone at the age of 15 after all the other chimpanzees of the group emigrated or disappeared. Since then he has been observed sporadically for more than five years only within the former range of K Group, without having any contact with the many resident chimpanzees of the neighboring M Group, the other major study group. The present observations reconfirm the strong philopatric tendency of adult male chimpanzees.     

Structure and affinities of the petrified plants from the cretaceous of Northern Japan and Saghalien XIIIYubaristrobus gen. nov., A new Taxodiaceous cone from the upper cretaceous of Hokkaido

Yubaristrobus is a new genus of the Taxodiaceae based on a permineralized seed cone from the Upper Cretaceous of Hokkaido. The type species,Y. nakajimae sp. nov., is characterized by peltate bract-scale complexes consisting of a completely-fused bract and scale. The bract-scale complexes are spirally arranged as in most taxodiaceous genera. Their vascular arrangement is specialized and unique in the Taxodiaceae and suggests a relationship with the Cupressaceae. Consecutive number from the previous paper (Ohsawa, M. Nishida and H. Nishida, 1992b).     

Artificial induction of chromosome aneuploidy in CHO cells alters their function as host cells

Chinese hamster ovary (CHO) cells are major host cells for biopharmaceuticals. During culture, the chromosome number of CHO cells alters spontaneously. Here, we investigated the effects of artificial changes in the chromosome number on productivity. When cell fusion between antibody-producing CHO-K1-derived cells was induced, we observed a wide range of aneuploidy that was not detected in controls. In particular, antibody productivities were high in clone-derived cell populations that retained a diverse chromosome number distribution. We also induced aneuploid cells using 3-aminobenzamide that causes chromosome non-disjunction. After induction of aneuploidy by 3-aminobenzamide, cells with an increased chromosome number were isolated, but cells with a decreased chromosome number could not be isolated. When antibody expression vectors were introduced into these isolated clones, productivity tended to increase in cells with an increased chromosome number. Further analysis was carried out by focusing on clone 5E8 with an average chromosome number of 37. When 5E8 cells were used as host, the productivity of multiple antibodies, including difficult-to-express antibodies, was improved compared with CHO-K1 cells. The copies of exogenous genes integrated into the genome were significantly increased in 5E8 cells. These findings expand the possibilities for host cell selection and contribute to the efficient construction of cell lines for recombinant protein production.     

Phase I/II trial of didanosine (2',3'-dideoxyinosine) in hemophiliac patients with AIDS or AIDS-related complex

Forty-three hemophiliacs with AIDS or ARC received a daily dose of 334 or 500 mg didanosine (2',3'-dideoxyinosine or ddI) orally in 2 divided doses in phase I/II, open-label clinical trial conducted in Japan. Twenty-eight patients completed 6 months of therapy. There was an increase in circulating CD4(+) cells in 19 valuable patients from 91 +/- 25 (mean +/- SE) at entry to 131 +/- 38 at 24 weeks of therapy P = 0.01; Wilcoxon signed rank). Fourteen of 37 patients met the criteria for CD4 rise >/= 50/mm3 rise or >/= 50% increase from entry values) for more than 4 consecutive weeks. Twenty patients were p24 positive at entry. Nine out of the 10 evaluable patients (90%) showed a decline in p24 antigen at weeks 20-24 (P = 0.02). Thirty-five patients had symptoms related to HIV-1 infection at entry. Twenty-seven patients reported improvements in constitutional symptoms during therapy. Nine patients presented with possible drug-related adverse effects, and didanosine was discontinued in 6 patients (one each with edema; abdominal pain with anorexia; hematuria with edema and rash; sense of abdominal distension with anorexia; diarrhea and abdominal pain; and irritability). One patient had a transient increase in serum amylase level to twice the upper limit of normal, but he continued to receive the drug. These data suggest that didanosine was generally well tolerated in hemophiliacs with AIDS or ARC, and its administration correlated with improvement in constitutional symptoms and laboratory findings. The adverse effects of didanosine seen in this population were moderate to mild, and no complications related to hemorrhagic diathesis were observed, although the relative risk of acute pancreatitis in this population (while not seen in the present study to date) requires more study.     

Physiological activities and the active constituents of potentially medicinal plants used by wild chimpanzees of the Mahale mountains,Tanzania

Potential medicinal plants for wild chimpanzees have been studied in order to discover their physiologically active compounds. Tests of the physiological activity of 3 plant species—Vernonia amygdalina, Aspilia mossambicensis, andFicus exasperata—indicate that they contain a variety of active compounds. From one species,V. amygdalina, an antitumor agent and 2 possible antitumor promoters are identified. Furthermore, steroid glucosides were isolated as the bitter substances. These structurally new compounds are expected to exhibit a number of significant physiological activities. The chemical investigation of possible medicinal plants used by chimpanzees should be helpful in recovering naturally occurring compounds of medicinal significance for human use.     

Schizosaccharomyces pombe Spk1 is a tyrosine-phosphorylated protein functionally related to Xenopus mitogen-activated protein kinase.

Mitogen-activated protein kinase (MAPK) and its direct activator, MAPK kinase (MAPKK), have been suggested to play a pivotal role in a variety of signal transduction pathways in higher eukaryotes. The fission yeast Schizosaccharomyces pombe carries a gene, named spk1, whose product is structurally related to vertebrate MAPK. Here we show that Spk1 is functionally related to Xenopus MAPK. (i) Xenopus MAPK partially complemented a defect in the spk1- mutant. An spk1- diploid strain could not sporulate, but one carrying Xenopus MAPK could. (ii) Both Spk1 and Xenopus MAPK interfered with sporulation if overexpressed in S. pombe cells. (iii) Spk1 underwent tyrosine phosphorylation as does Xenopus MAPK. Tyrosine phosphorylation of Spk1 appeared to be dependent upon mating signals because it occurred in homothallic cells but not in heterothallic cells. Furthermore, this phosphorylation was diminished in a byr1 disruptant strain, suggesting that spk1 lies downstream of byr1, which encodes a MAPKK homolog in S. pombe. Taken together, the MAPKK-MAPK cascade may be evolutionarily conserved in signaling pathways in yeasts and vertebrates.     

Sequence evolution of mitochondrial tRNA genes and deep-branch animal phylogenetics

Mitochondrial DNA sequences are often used to construct molecular phylogenetic trees among closely related animals. In order to examine the usefulness of mtDNA sequences for deep-branch phylogenetics, genes in previously reported mtDNA sequences were analyzed among several animals that diverged 20–600 million years ago. Unambiguous alignment was achieved for stem-forming regions of mitochondrial tRNA genes by virtue of their conservative secondary structures. Sequences derived from stem parts of the mitochondrial tRNA genes appeared to accumulate much variation linearly for a long period of time: nearly 100 Myr for transition differences and more than 350 Myr for transversion differences. This characteristic could be attributed, in part, to the structural variability of mitochondrial tRNAs, which have fewer restrictions on their tertiary structure than do nonmitochondrial tRNAs. The tRNA sequence data served to reconstruct a well-established phylogeny of the animals with 100% bootstrap probabilities by both maximum parsimony and neighbor joining methods. By contrast, mitochondrial protein genes coding for cytochrome b and cytochrome oxidase subunit I did not reconstruct the established phylogeny or did so only weakly, although a variety of fractions of the protein gene sequences were subjected to tree-building. This discouraging phylogenetic performance of mitochondrial protein genes, especially with respect to branches originating over 300 Myr ago, was not simply due to high randomness in the data. It may have been due to the relative susceptibility of the protein genes to natural selection as compared with the stem parts of mitochondrial tRNA genes. On the basis of these results, it is proposed that mitochondrial tRNA genes may be useful in resolving deep branches in animal phylogenies with divergences that occurred some hundreds of Myr ago. For this purpose, we designed a set of primers with which mtDNA fragments encompassing clustered tRNA genes were successfully amplified from various vertebrates by the polymerase chain reaction.Abbreviations AA stem amino acid-acceptor stem - AC stem anticodon stem - COI cytochrome oxidase subunit I - cytb cytochrome b - D stem dihydrouridine stem - MP maximum parsimony - mtDNA mitochondrial DNA - Myr million years - NJ neighbor joining - PCR polymerase chain reaction - Ti transition - T stem tC stem - Tv transversion Correspondence to: Y. Kumazawa