Abscisic Acid as a Stimulator for Rice Mesocotyl Growth

WHEN abscisic acid (ABA) is applied to a growing plant, it usually inhibits the growth of stem, leaf sheath and other plant parts^1–3. Here I report the possibility that ABA stimulates the growth of rice mesocotyl in darkness.     

Evidence for Naturally Occurring Inhibitors of Archegonial Differentiation in Lygodium japonicum

Archegonial differentiation in prothallia of Lygodium japonicum was inhibited when the filtrate of conditioned medium or the extracts of prothallia with organic solvents were added to the medium. By varying the timing of treatment with the methanol extract, archegonial differentiation was shown to start at least 4 days before microscopically detectable change. The inhibitory effect of methanol extract was nullified by transferring the treated plants to a fresh medium omitting the methanol extract, so that the archegonial formation became discernible 6 days after the transfer. The inhibitory activity was stable in both acidic and basic solutions at room temperature, and was partially lost by boiling at pH 3 or 11 for 30 min. The inhibitor, which could be retrieved from the filtrate and the methanol extract, was fractionated into the neutral ethyl acetate fraction, but was not found in the acidic ethyl acetate fraction and in the aqueous residue. At least two active zones were separated on thin layer chromatograms of the ethyl acetate extracts from the filtrate and the methanol extract, and the relative flow-rates of each active zone from these two sources were very similar. The evidence described above indicates that specific inhibitors of archegonial differentiation may be produced in the tissue of prothallia of Lygodium and eventually be secreted to the medium.     

Adult eclosion rhythm of the Indian meal moth Plodia interpunctella: response to various thermocycles with different means and amplitudes

In addition to photoperiod, thermoperiod (or thermocycle) might be an important Zeitgeber for entraining the circadian oscillator controlling adult eclosion rhythm in the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae). This is confirmed by exposing larvae receiving diapause‐preventing treatments to various thermocycles with different means and amplitudes of temperature. The thermocycles investigated in the present study are TC 8 : 16 h, TC 12 : 12 h, TC 16 : 8 h and TC 20 : 4 h, where T and C represent thermophase (30 °C) and cryophase (20 °C), respectively. For all thermocycles, the peak of adult eclosion rhythm occurs at around the mid‐thermophase. This indicates that the larvae use both ‘temperature‐rise’ and ‘temperature‐fall’ signals to adjust the eclosion phase in each thermocycle. The absence (DD) or presence (LL) of light affects this time‐keeping system slightly under the given thermocycle. The rhythmic adult eclosion noted after exposure of larvae to 30 °C DD for 14 days is recorded in the thermocycles (TC 12 : 12 h, DD; mean temperature = 25 °C) with different amplitudes of 27.5/22.5 °C, 26.5/23.5 °C and 25.5/24.5 °C. The peak in adult eclosion advances in time as the amplitude of the temperature cycle decreases. In the temperature cycle of 25.5/24.5 °C, a peak occurs at the end of the cryophase, 2 h before the temperature‐rise. The adult eclosion rhythm is also observed under various thermocycles (TC 12 : 12 h, DD) consisting of different temperature levels (30 to 20 °C) with different amplitudes. It is found that the temporal position of the peak advances significantly when the amplitude of the thermocycle becomes lower.     

Choanoflagellates (Sarcomastigophora, Protozoa) from the Coastal Waters of Taiwan and Japan. I. Three New Species

Three new acanthoecidaean species collected from the coastal waters of Taiwan and Japan are described: Acanthocorbis camarensis n. sp. resembles Acanthocorbis unguiculata in lorica morphology, but differs in having regularly arranged longitudinal and transverse costae at the anterior lorica chamber, and in lacking a nail at the apical end of anterior spine; Diaphanoeca spiralifurca n. sp. is characterized by the spiral arrangement of the costal strips in the posterior half of the lorica chamber and is closely related to Diaphanoeca grandis; Stephanoeca supracostata n. sp. is closely related to Stephanoeca elegans, but differs in having an additional transverse costa at the anterior lorica chamber.     

Erythrocyte Membrane-specific Antigens common to Several Species of Rodentia

THE rare existence of organ-specific antisera transcending species differences was pointed out by Coombs¹. Similar new organ, or “erythrocyte-specific”, antisera reacting selectively to the erythrocytes of several species of Myomorpha are described here. The antisera, “anti-A”, were prepared by the method of Adachi and Furusawa²: adult guinea-pigs were sensitized with the “antigen-A” (the protein portion of dd mouse erythrocyte membrane). The detailed procedure for preparing labelled antibody, the staining method and its specific reactivity to mouse erythrocytic cells have been reported before³. Circulating erythrocytes from various animals were stained with the fluorescein isothiocyanate-labelled “anti-A”. Smeared cell preparations were fixed with acetone at ? 20° C for 20 min and incubated with the labelled antisera, which had been thoroughly absorbed with the emulsion of mouse liver and kidney to remove the cross-reacting antibodies, at 37° C for 90 min. A light microscope with a darkfield condenser was used for the fluorescent observations using Orsen's interference filter system. Clear fluorescent reactions, though of varied intensities, were observed with those animals classified as Myomorpha, that is, mouse, rat, golden hamster and Chinese hamster (Table 1, Fig. 1). Mammalian erythrocytes other than those of the guinea-pig used as the sensitized animal showed faint fluorescences. Nucleated erythrocytes of the chick, quail, turtle, toad and goldfish were negative to the reaction. The erythrocyte-specific reactivity of the labelled antisera was examined with the liver, kidney and thymus cells of the animals whose erythrocytes displayed intense fluorescences; they showed, however, no fluorescence.     

SORBITOL IN THE EGGS OF THE SILKWORM, BOMBYX MORI

Sorbitol was found to be a normal and sole monosaccharide demonstrable in the late ovarian and in the early embryonic stages of the silkworm, Bombyx mori. This observation was first made on a line of non-diapausing polyvoltine Katsumata strain, but was later confirmed by the analysis of two other Katsumata lines and on several polyvoltine or bivoltine strains. The identification of the sugar extracted from the diapause eggs of a bivoltine strain and from the non-diapausing eggs of a Katsumata strain was based on analyses involving paper chromatography, paper electrophoresis and sorbitol dehydrogenase.     

Changes in Nicotinamide Nucleotide Coenzymes in Cucumber Leaves during Ammonium Toxicity

Nicotinamide nucleotide coenzymes were estimated enzymatically in cucumber leaves (Cucumis sativus L. cv. Suisei No. 2) during ammonium toxicity. The contents of all the coenzymes (NAD(H) and NADP(H)) were found to be higher in the ammonium-treated plants than in the control plants, and the difference attained a maximum at 5 days after the initiation of ammonium treatment. Thereafter, the contents of NAD and NADH returned towards the control level, but NADP and NADPH levels were lowered in injured plants. The ratios of NAD/NAD + NADH and NADP/NADP ++ NADPH were little altered by the ammonium treatment. Changes of nicotinamide nucleotide coenzymes are discussed in relation to respiratory metabolism in cucumber leaves during ammonium toxicity.     

Localization of Possible Calcium-Binding Sites in the Cilia of Paramecium caudatum

SYNOPSIS. Electron-dense deposits indicating possible Ca-binding sites were found at the ciliary base of Paramecium caudatum fixed in a glutaraldehyde solution containing 5 mM CaCl₂. The deposits appeared mainly at the inner surface of the ciliary membrane above the "ciliary necklace" region, although they could also occur in the space between the outer and the central microtubules. In some cases a ring of exactly 9 deposits was found in a ciliary cross section of a cilium.     

CHICK BRAIN CREATINE KINASE ONTOGENY BEFORE THE ADVENT OF CREATINE AND INSULIN

The ontogeny of brain creatine kinase (CK) was studied during chick embryo development. The cytosolic activity increased 270% in 10 h from the 2nd to the 3rd days of incubation; this was followed by a plateau phase throughout development and at the end of incubation there appeared to be another increase of cytosolic and mitochondrial CK activities. Therefore, early embryonic chick brain CK is another‘constitutive’enzyme like the early embryonic chick heart CK since creatine has not been enzymatically detected in the embryo until day 4 of incubation. Insulin does not appear to stimulate the early increase of brain CK activity since the hormone is not present in the embryo until day 5 of incubation. It is likely that CK increase is associated with neuronal multiplication at early stages and possibly to neuronal maturation before hatching.     

Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size

Divergent natural selection is thought to play a vital role in speciation, but clear, measurable examples from nature are still few. Among the many possible sources of divergent natural selection, predation pressure may be important because predators are ubiquitous in food webs. Here, we show evidence for divergent natural selection in a Lake Tanganyika cichlid, Telmatochromis temporalis , which uses burrows under stones or empty snail shells as shelters. This species contains normal and dwarf morphs at several localities. The normal morph inhabits rocky shorelines, whereas the dwarf morph invariably inhabits shell beds, where empty snail shells densely cover the lake bottom. Genetic evidence suggested that the dwarf morph evolved independently from the normal morph at two areas, and morphological analysis and evaluation of habitat structure revealed that the body sizes of morphs closely matched the available shelter sizes in their habitats. These findings suggest that the two morphs repeatedly evolved through divergent natural selection associated with the strategy for sheltering from predators.