Development of microsatellite markers in the noxious red tide‐causing dinoflagellate Heterocapsa circularisquama (Dinophyceae)

We isolated 15 polymorphic microsatellites from one of the most noxious red tide‐causing dinoflagellate species, Heterocapsa circularisquama. These loci provide one class of highly variable genetic markers, as the number of alleles ranged from two to six, and the estimate of gene diversity from 0.205 to 0.684 across the 15 microsatellites. These loci have the potential to reveal genetic structure and gene flow among H. circularisquama populations.     

Development of microsatellite markers in the toxic dinoflagellate Alexandrium minutum (Dinophyceae)

Outbreaks of paralytic shellfish poisoning caused by the toxic dinoflagellate Alexandrium minutum (Dinophyceae) are a worldwide concern from both the economic and human health points of view. For population genetic studies of A. minutum distribution and dispersal, highly polymorphic genetic markers are of great value. We isolated 12 polymorphic microsatellites from this cosmopolitan, toxic dinoflagellate species. These loci provide one class of highly variable genetic markers, as the number of alleles ranged from four to 12, and the estimate of gene diversity was from 0.560 to 0.862 across the 12 microsatellites; these loci have the potential to reveal genetic structure and gene flow among A. minutum populations.     

Isolation of Zn2+ as an Endogenous Agonist of GPR39 from Fetal Bovine Serum

We attempted to determine natural agonists of GPR39 in fetal bovine serum (FBS). FBS was conditioned to extract peptides and fractionated by two types of HPLC. The activity of each fraction was monitored by intracellular calcium mobilization. Then the purified active ingredient was analyzed by inductively coupled plasma mass spectrometry. In this fashion, Zn^{2 +} ion was identified as an agonist of GPR39, though no peptidergic molecules were found. The calcium-mobilizing activity of Zn^{2 +} was not abolished by pertussis toxin but was by a phospholipase C (PLC) inhibitor, U73122, indicating that the activity of GPR39 is mediated through the G_qα -PLC pathway. In addition, Zn^{2 +} also activated mouse and rat GPR39, showing that the function of GPR39 as a Zn^{2 +} receptor is conserved across species. This study is the first exploration of GPR39 agonists in FBS and indicates that GPR39 functions as a Gq-coupled Zn^{2 +}-sensing receptor.     

DOES COLCHICINE AFFECT AGGREGATION OF NORMAL AND TRANSFORMED BHK CELLS DIFFERENTLY?

The effect of colchicine and vinblastine on cell aggregation was studied, using BHK cells and their transformed derivatives (pyBHK cells). When cells were dissociated with EDTA and the assay was made in a Ca²⁺-containing medium, the aggregation of transformed cells was prevented by colchicine and vinblastine, whereas the aggregation of normal cells was unaffected. When a Ca²⁺-free medium was used for aggregation, neither type of cell was influenced by these drugs. BHK and pyBHK cells, dissociated by trypsin in the presence of Ca²⁺, can aggregate only in the Ca²⁺-containing medium and the aggregation of both cell types was equally prevented by colchicine and vinblastine. Based on these results, it was concluded that colchicine and vinblastine inhibited the Ca²⁺-dependent mechanism of cell adhesion, but not the Ca²⁺-independent one which occurs in the Ca²⁺-free aggregation medium.     

Induction of DNA synthesis by 2,4-dichlorophenoxyacetic acid during callus induction in Jerusalem artichoke tuber tissues

During the induction of DNA synthesis in Jerusalem artichoke (Helianthus tuberosus L.) tuber by 2,4-D, the 2-¹⁴C-2, 4-D from the agar medium rapidly incorporated into the ethanol soluble and insoluble fractions. Although the 2,4-D level in the ethanol soluble fraction decreased on transplantation of the tissue from the 2-¹⁴C-2,4-D medium to medium without the auxin, its level in the buffer-soluble and -insoluble macromolecular fractions increased. The purified, buffer-insoluble macromolecules were chromatin. The 2,4-D binding to chromatin particularly increased during DNA synthesis. The histone contents of chromatin decreased as DNA synthesis progressed. The polyacrylamide gel electrophoretic patterns of the histones showed a decrease in the moderately lysine-rich histone fraction as compared to other fractions. Thus, the decrease in the histone level caused by 2,4-D and the presence of the 2,4-D moderately lysine-rich histone complex may be closely related to the induction of DNA synthesis by 2,4-D in cells.     

Further Evidence for the Presence of a Circadian Clock in the Prothoracic Glands of the Saturniid Moth Samia cynthia ricini: Decapitated Larvae Can Respond to Light-Dark Changes

A small peak of haemolymph ecdysteroid titre precedes the gut purge that characterizes larval-prepupal transition of the saturniid moth Samia cynthia ricini. This peak shifts its phase in parallel with the phase shifts of gut purge according to the changes in light-dark conditions preceding gut purge. Decapitated larvae responded to these light-dark changes as intact larvae did, as assessed by the phase shifts of the haemolymph ecdysteroid peak. This indicates that the brain-centred PTTH clock is not prerequisite for realization of the circadian-clock-controlled timing in the initiation of prepupal development, and supports indirectly our previous notion that the prothoracic glands of Samia possess a circadian clock dictating gut purge timing.     

Intra-guild predation and variation in egg defence between sympatric and allopatric populations of two species of ladybird beetles

Abstract.  1. Ladybird eggs are defended chemically against intra-guild predation, and are unsuitable to varying degrees as food for other ladybirds.
2. Ladybird eggs [ Coccinella septempunctata (Cs) and Harmonia axyridis (Ha); Coleoptera: Coccinellidae] from local Japanese versus North American populations were compared as food for two ladybirds (Cs and Ha) co-occurring in Japan.
3. Larvae of Cs exhibited high mortality, slow development, and reduced egg consumption and weight gain when they fed on Ha versus conspecific eggs, especially when Ha eggs were from the local (Japanese) population versus a distant (North American) population of Ha.
4. Larvae of Ha survived equally well on a diet of Cs or conspecific eggs, but developed more slowly and gained less weight on Cs eggs. Ha larvae were more reluctant to eat eggs from the local (Japanese) population of Cs than eggs from the distant (North American) population of Cs; however, other measures of performance did not differ significantly.
5. These results indicate greater egg chemical defence of Ha eggs against Cs larvae than vice versa, as expected from field observations of greater temporal overlap between Cs larvae and Ha eggs than between Ha larvae and Cs eggs. Furthermore, results also indicate that local populations of eggs are better defended than eggs from elsewhere against locally occurring intra-guild predators. Thus, it appears that the effectiveness of chemical defence of ladybird eggs reflects the degree to which specific pairings of ladybirds have the potential to interact in nature through egg predation.     

The Ontogeny of Thymic Myoid Cells in the Chicken

The ontogeny of thymic myoid cells in the chick was studied electron microscopically and immunohistochemically. An anticreatine kinase antibody which reacts specifically to skeletal muscle cells was used. This antibody reacts only to myoid cells in the thymus. Myoid cells were found in the medulla or in the interlobular region, though the number of the myoid cells was small. Immunohistochemically, myoid cells were detected on the 18th day of incubation. Mature myoid cells showed clear cross striations after immunohistochemical staining around the time of hatching. Electron microscopically, myoid cells were detectable on the 19th day of incubation. The discrepancy between immunohistochemical and electron microscopical detection may be due to the low number of myoid cells.     

VITELLOGENIN IN THE EGGS OF THE COCKROACH, BLATTELLA GERMANICA: PURIFICATION AND CHARACTERIZATION

Vitellogenin in the eggs of Blattella germanica was solubilized with solutions at high salt concentrations and high pH. This protein was purified by ammonium sulfate precipitation, acetic acid precipitation, DEAE-cellulose chromatography, and hydroxylapatite chromatography, into a chromatographically homogeneous state. By sucrose density gradient centrifugation, the purified vitellogenin was resolved into two components. The relative amounts of the two components varied according to the pH of the solution. An equilibrium seemed to exist in the interconversion between them when the conditions of the solution were fixed. It is suggested that aggregation and disaggregation of the vitellogenin molecules may account for the apparent heterogeneity.