Biochemical assessment of evolution and taxonomy of the morphologically poorly diverged geckos, Gekko yakuensis and G. hokouensis (Reptilia: Squamata) in Japan, with special reference to their occasional hybridization

We assessed the validity of two gekkonid species, Gekko yakuensis and G. hokouensis, in southern Japan. We first assigned all 398 specimens into 18 samples merely on the basis of localities. By conducting significance test for deviations of genotype frequencies from Hardy‐Weinberg at 11 allozyme loci, we checked the reproductive unity of constituents in each of those local samples, and where necessary, rearranged them into subsamples on the basis of genetic markers so that we recognized minimum reproductively cohesive units. We then compared allele frequencies among all samples and subsamples examined. Results clearly indicated that all but two can be classified into two groups that can be discriminated from each other by remarkable allele frequency differences at four diagnostic loci, and by large genetic distances even between sympatric subsamples. Observations of morphological features of the samples and subsamples confirmed that the two groups correspond to G. yakuensis and G. hokouensis, supporting validities of these two species. Allele frequency comparisons, however, also revealed that the remaining two samples, both from southern Kyushu, possessed ‘marker alleles' of both G. yakuensis and G. hokouensis at all four diagnostic loci. These samples thus were considered to represent populations that have been derived through hybridization of the two species. Detailed analyses for genetic structures demonstrated that all hybrid genotypes in the two samples are post‐Fi generations with only one individual resulting from the back‐cross with a pure line population of G. yakuensis. This finding negates the possibility that the hybrid populations are maintained by a constant supply of newly produced Fj hybrids, but suggests that the hybrid genotypes constitute stable breeding populations. This implies that the genealogical independence of G. yakuensis and G. hokouensis in several other sympatric areas has been maintained by operations of some isolation mechanisms at a pre‐mating phase. Investigations of the morphological variation in each sample or subsample revealed that although the two species can be externally largely discriminated from each other by slight modifications of the currently used diagnoses, it is difficult to detect their hybrids based solely on the morphological features.     

Fighting, dispersing, and sneaking: body-size dependent mating tactics by male Librodor japonicus beetles

Abstract.  1. Scaling relations between weapons and body size depart from linearity in many male beetles. In many previous studies, these males have been divided into major and minor males with a switch point, that is male dimorphism. Major and minor males adopt strikingly different reproductive tactics.
2. We found three size-dependent behaviours, i.e. fighting, dispersing, and sneaking, however, among Librodor japonicus males with dimorphic mandibles. We statistically classified males into large, medium, and small (L-, M-, and S-males) sizes and then compared the dispersal of males from a foraging site, behaviours to gain access to females, and sizes of mandibles, wings, and testes.
3. M-males dispersed earlier than L- and S-males from a territory in a field, but no difference in the frequency of dispersal was observed between L- and S-males. Observations of male–male interactions in the laboratory showed that L-males frequently fought with other males in a fighting arena, while S-males often showed sneaking behaviour without fighting.
4. On the basis of the morphological analysis, we concluded that S-males invested their available resources more in sperm (= testes), M-males more in wings, and L-males more in mandibles in L. japonicus .
5. Even though a morphological male dimorphism was detected, it might be possible to classify the males of the armed beetles into more than two behavioural tactics if we examine their behaviours.     

Light-induced absorbance change of carotenoid in chromatophores of photosynthetic bacterium, Rhodopseudomonas spheroides

The nature of the light-induced absorbance change of carotenoid,spheroidene, was investigated with the chromatophores of Rhodopseudomonasspheroides. The experimental results indicate that the changedoes not represent an oxidation-reduction reaction of the carotenoid,but is caused by a change in the state of the chromatophoresclosely related to the high energy state of the photophosphorylation.Since the change almost vanishes at liquid nitrogen temperature,it probably does not represent a primary photochemical reactionin the chromatophores. The values of the quantum yield for thechange of carotenoid were above unity ; 2.5 on an avera (Received November 20, 1969; )     

AN ANALYSIS ON THE TROPISM IN HVJ (SENDAI VIRUS) INFECTION: MANIFESTATION OF HIGH VIRAL SUSCEPTIBILITY IN SPREADING CULTURES OF ISOLATED ALLANTOIC EPITHELIAL CELLS OF THE CHICK EMBRYO

By culturing pure allantoic epithelial cells separated from the chorioallantoic membrane of a 10-day-old chick embryo, sheets of monolayered epithelial cells were obtained and maintained for at least one week. These cells were highly susceptible to infection with HVJ (Sendai virus) in vitro . In similarly cultured mesenchymal cells of the chorioallantoic membrane, the susceptibility was found to be very low. It was concluded that the tropism observed in HVJ infection in vitro can be explained by differences in the susceptibility to HVJ among various cell types.     

Detection of the Initial Step of Mesenchymal Differentiation of Teratocarcinoma Cells Using the Monoclonal Antibody Eccd-11

The monoclonal antibody ECCD-1 recognizes the Ca²⁺-dependent cell-cell adhesion molecule of teratocarcinoma stem cells (EC cells) and of a certain class of differentiated epithelial cells. It actively disrupts cell-cell adhesion when added to monolayer cultures of these cells, but does not affect adhesion of mesenchymal or neuronal cells. When ECCD-1 was added to clonal cultures of EC cells (PCC3/A/1 line), all the cells were initially sensitive to the antibody, but after 5 to 6 days of culture a fraction of the cells in certain colonies no longer reacted with the antibody although they expressed alkaline phosphatase activity, which is a marker of undifferentiated EC cells. We isolated these ECCD-1-resistant cells by recloning and examined their differentiation by clonal culture. Most of them differentiated into fibroblastic cells and a few into skeletal muscle-like cells, but none differentiated into any other cell types. From these observations, we suppose that the ECCD-1-resistant population of EC cells are committed to mesenchymal differentiation. The use of ECCD-1, thus, permitted us to detect EC cells at the initial stage of a particular differentiation pathway.     

CELL WALL POTENTIAL IN NITELLA

In the process of inserting a microelectrode into the vacuoleof Nitella three potential levels were recorded. The first onewas at a water phase outside the cell wall, the second one inthe cell wall and the third one across the plasmalemma. Thefirst potential was variable with the distance from the surfaceof the cell wall. When the external solution was 10^–4M KCl, the second potential level was –90 mv and the thirdone –170 mv against an external reference electrode. Thesepotentials were less negative (more negative) with the increase(decrease) of the external KCl concentration and varied to someextent among samples. The vacuolar potential measured againstthe cell wall phase was, therefore, –80 mv inside negativeto outside. A large potential change such as action potentialwas observed only across the plasmalemma. An overshoot of theaction potential of Nitella flexilis was observed very often,when the vacuolar potential was measured against the cell wallphase. This work was supported by a Research Grant from the Ministryof Education of Japan. Part of this work was performed whenR. NAGAI was a Yukawa Research Grant fellow.