Lamprey buccal gland secretory protein-2 (BGSP-2) inhibits human T lymphocyte proliferation

Lamprey is a representative of the agnathans, the most ancient class of vertebrates. Parasitic lampreys secrete anticoagulantfrom their buccal glands and prevent blood coagulation of host fishes. We identified a buccal gland secretory protein-2(BGSP-2) from a buccal gland cDNA library of Lampetra japonica. The full-length BGSP-2 gene was cloned and the recombinantBGSP-2 protein was generated. The role of BGSP-2 on lymphocyte proliferation was studied by examining its effects onhuman T lymphocytes. We found that lamprey BGSP-2 was able to effectively block the proliferation of T cells in vitro by inducingG_1/S cell cycle arrest. Furthermore, it inhibited the proliferation of human T lymphocytes stimulated by phytohemagglutinin(PHA) at a minimum concentration of 0.1μg/ml. Our data suggest that lamprey BGSP-2 is able to block the mitosis of humanT lymphocytes at the G1/S point, and has the potential of anti-proliferative effect on PHA-activated T

Phylogenetic analysis of 48 gene families revealing relationships between Hagfishes, Lampreys, and Gnathostomata

It has become clear that the extant vertebrates are divided into three major groups, that is, hagfishes, lampreys, and jawed vertebrates. Morphological and molecular studies, however, have resulted in conflicting views with regard to their interrelationships. To clarify the phylogenetic relationships between them, 48 orthologous protein-coding gene families were analyzed. Even as the analysis of 34 nuclear gene families supported the monophyly of cyclostomes, the analysis of 14 mitochondrial gene families suggested a closer relationship between lampreys and gnathostomes compared to hagfishes. Lampreys were sister group of gnathostomes. The results of this study supported the cyclostomes. Choice of outgroup, tree-making methods, and software may affect the phylogenetic prediction, which may have caused much debate over the subject. Development of new methods for tackling such problems is still necessary.

Comparative analysis of mitochondrial fragments transferred to the nucleus in vertebrate

Mitochondrial DNA sequences transferred to the nucleus give rise to the so-called nuclear mitochondrial DNA （numt）. In the GenBank database, 244 numts have been found in six orders of birds （Anseriformes, Columbiformes, Falconiformes, Charadriiformes, Galliformes and Passeriformes）. Sequences alignment （NCBI-BLASTN） was carded out with mitochondrial and corresponding nuclear genome sequences in nine vertebrate species. The sequences with high homology were considered as numts. The number of numts ranged from 15 in chicken to 159 in chimpanzee. The sequences of numts in macaque, chimpanzee, and human spanned 100% of the entire mammalian mitochondrial genome. The reconstructed frequency of the mitochondrial gene transferred to the nucleus demonstrated that the rRNA genes had high frequencies than other mitochondrial genes. Using the RepeatMasker program, the transposable elements were detected in the flanking regions of each numt. The results showed that less than 5% of the flanking sequences were made up of repetitive elements in chicken. The GC content of 5＇- and 3＇-flanking regions of numts in nine species was less than 44%. The analysis of the flanking sequences provided a valuable understanding for future study on mechanism of mitochondrial gene transfer to the nucleus and the site of numt integration.