Studies on germination of chrysanthemum pollen II. Occurrence of a germinationpromoting substance

The in vitro germination of chrysanthemum pollen is promotedby adding floral organs, excepting anther, to a basal mediumconsisting of sucrose and boric acid. Some other plant organs,such as young fruit of tomato and onion bulb, are also effective.In Chrysanthemum morifolium, the percentage of pollen germinationin the presence of such plant tissues is two to three timesas high as in the control (10 %). In Ch. leucanthemum, it ishigher than 50 %, in contrast to the control in which no germinationis noted. This promotion of germination may be due to a substance extractablefrom the tissues with water, ether or methanol. The promoting substance is not identical with several knowngrowth regulators or with the Ca ion. (Received November 21, 1967; )     

Quantitation and Visualization of Ultraviolet‐Induced DNA Damage Using Specific Antibodies: Application to Pigment Cell Biology

The major types of DNA damage induced by sunlight in the skin are DNA photoproducts, such as cyclobutane pyrimidine dimers (CPDs), (6‐4)photoproducts (6‐4PPs) and Dewar isomers of 6‐4PPs. A sensitive method for quantitating and visualizing each type of DNA photoproduct induced by biologically relevant doses of ultraviolet (UV) or sunlight is essential to characterize DNA photoproducts and their biological effects. We have established monoclonal antibodies specific for CPDs, 6‐4PPs or Dewar isomers. Those antibodies allow one to quantitate photoproducts in DNA purified from cultured cells or from the skin epidermis using an enzyme‐linked immunosorbent assay. One can also use those specific antibodies with in situ laser cytometry to visualize and measure DNA photoproducts in cultured cells or in the skin, using indirect immunofluorescence and a laser‐scanning confocal microscope. This latter method allows us to reconstruct three‐dimensional images of nuclei containing DNA photoproducts and to simultaneously examine DNA photoproducts and histology in multilayered epidermis. Using those techniques, one can determine the induction and repair of these three distinct types of DNA photoproducts in cultured cells and in the skin exposed to sublethal or suberythematous doses of UV or solar simulated radiation. As examples of the utility of these techniques and antibodies, we describe the DNA repair kinetics following irradiation of human cell nuclei and the photoprotective effect of melanin against DNA photoproducts in cultured pigmented cells and in human epidermis.     

INSTABILITY OF MESSENGER AND RIBOSOMAL RNA IN A GLUE-PROTEIN MUTANT OF Bombyx mori

The mucous glands of Bombyx pupae secrete glue proteins which attach deposited eggs to the mounting sheet. A mutant of a dominant gene, named no glue (Ng) , produces nonadhesive eggs which have a low capacity for glue-protein synthesis. In the present study it was shown that the mucous glands of Ng silkworms showed rapid degradation of mRNA as well as rRNA during development; this may cause the low capacity for glue-protein synthesis in the mutant organ. In contrast, the mucous glands of normal silkworms showed a significant increase in content of RNA's until the maximum rate of glue-protein synthesis was achieved. The degradation of RNA in the Ng mucous gland was inhibited by actinomycin D injected into the body fluid. Thus it is supposed that the Ng gene codes for a presumptive controller RNA, which would be the mediator of RNA instability in the mucous glands of Ng pupae.     

A seed parasitoid wasp prevents berries from changing their colour,reducing their attractiveness to frugivorous birds

1. Frugivorous and seed‐feeding insects may alter the traits of fruits, such as shape and size, which may influence fruit attractiveness to frugivorous birds. Consequently, trait‐mediated interactions may occur in systems where plants, seed‐dispersing frugivorous vertebrates, and frugivorous or seed‐feeding insects interact. We investigated colour manipulation in Ilex integra Thunb. berries caused by the seed parasitoid wasp Macrodasyceras hirsutum Kamijo and how that manipulation relates to fruit attractiveness for frugivorous birds. 2. In winter, the colour of I. integra berries varied from green to red, but most berries were greenish, indicating that the berries were immature. Berry dissection indicated that the number of live parasitoid larvae present within each berry was closely related to berry colour – the greater the number of live larvae, more intense is the green colour of the berry. However, the wasp larvae did not modify the shape or size of the berries. More than 98% of berries that were protected from the insects by gauze bags ripened and turned red. In the present study, berries with unfertilised seeds alone turned red. Field‐feeding preference tests showed that the brown‐eared bulbul Hypsipetes amaurotis Temminck preferred red berries to green berries. 3. We demonstrated that the seed parasitoid wasp manipulates the berry colour, but not its shape or size, in a density‐dependent manner. Because green berries suffered less from bird foraging, we believe that this colour manipulation helps the wasps to avoid being killed by the birds. The present study indicates that manipulation by wasps may reduce the level of mutualism between the tree and seed‐dispersing birds.     

RECONSTRUCTION OF AN APPARATUS OF NEOSTRACHANOGNATHUS TAHOENSIS FROM ORITATE,JAPAN AND SPECIES OF NEOSTRACHANOGNATHUS FROM OMAN

Abstract: The apparatus of an Early Triassic conodont Neostrachanognathus tahoensis Koike, 1998 from Oritate, Kumamoto Prefecture, Japan, and a species of Neostrachanognathus from Oman were reconstructed. On the basis of five natural assemblages from the Oritate area, the three‐dimensional apparatus model of N. tahoensis is interpreted as bilaterally symmetrical and composed of 14 elements consisting of pairs of P₁, P₂, P₃, S₁, S₂, S₃, and S₄ elements. The P₁ and P₂ elements are coniform elements, the P₃ elements are digyrate forms, and the S elements are bipennate ramiforms. The S elements are arranged rostrally in the apparatus and the pairs of the P₁, P₂, and P₃ elements are subvertically arranged caudally and ventrally to the S array. One of the natural assemblages was formed by rostrocaudal collapse of the apparatus on the sea floor, whereas the other assemblages indicate that conodont animals came to rest nearly parallel with the substrate prior to burial. A collection of isolated elements from Jabal Safra, Oman, includes a second species of Neostrachanognathus with a comparable apparatus.     

A new anhydrobiotic midge from Malawi,Polypedilum pembai sp.n. (Diptera: Chironomidae), closely related to the desiccation tolerant midge,Polypedilum vanderplanki Hinton

The sleeping chironomid (Polypedilum vanderplanki Hinton) lives on temporary rock pools in the semi‐arid tropical regions of Africa. Its larvae are able to survive the dry season in a completely desiccated ametabolic state known as anhydrobiosis. So far, P. vanderplanki was the only species among all insects showing demonstrated anhydrobiotic ability. Here, we show that a new related species originating from Malawi, Polypedilum pembai sp.n. , is also anhydrobiotic and that its desiccation tolerance mechanism is probably similar to what is observed in P. vanderplanki. The new species, P. pembai sp.n. , is described with special attention to the common and different morphological features, compared with P. vanderplanki. Phylogenetic analysis showed that both species are closely related, suggesting that anhydrobiosis evolved only once in their common ancestor about 49 Ma somewhere in Africa, before the divergence of two species, one in the sub‐Saharan area and another in southeastern Africa.     

Studies on Unequal Cleavage in Sea Urchins II. Surface Differentiation and the Direction of Nuclear Migration

Cortical features of the meso- and macromeres differ from those of the micromeres in sea urchins. At the end of the 8-cell stage, the four animal cells have a continuous row of vesicles lining the free surface of the cell by transmission electron microscopy (TEM) and the nuclei and the resulting mitotic apparatuses (MA) remain at the cell centers and eventually divide equally into eight mesomeres. In the four vegetal cells, narrow gaps can be seen in the vesicular rows near the vegetal pole. The resting nuclei migrate to these gaps and on forming the spindles, they point directly to the gaps. The result is formation of vesicle-free micromeres and vesicle-covered macromeres by unequal divisions.     

Homoeotic Gene ETc Controls the Cell Number of Embryonic Ectodermal Layers of Bombyx mori

The formation of segments of Bombyx larvae involves differentiation of legged and legless segments during embryogenesis. Observations by light microscopy of serial sections of developing embryos of Bombyx showed that the cell number of the ectodermal layers increased more rapidly in segments where legs were being extruded than in those where no appendages were formed. In the embryos of a homoeotic mutant for the E -pseudoallelic locus (about 0.0–VI), E^Tc/E^Tc , in which all the abdominal segments were legless, the cell number of the ectodermal layers did not increase as in normal embryos. These findings suggest that the E^Tc gene controls the cell number of the ectodermal layers in relation to the differentiation of abdominal segments.     

Initiation of Sperm Motility Induced by Cyclic AMP in Hamster and Boar

When the plasma membrane of hamster and boar spermatozoa was extraced by treatment with Triton X-100 and the demembranated spermatozoa were transferred to a reactivating medium containing only ATP, axonemes were initially immotile, and then gradually became motile. Under these experimental conditions, the cAMP content in the reactivating medium increased soon. This suggests that cAMP is synthesized from ATP by adenylate cyclase involved in incompletely removed or solubilized residual sperm membrane and that the autosynthesized cAMP causes the delay in motility initiation. This delayed initiation of motility did not occur when phosphodiesterase was added to the reactivating medium and the phosphodiesterase-dependent quiescent sperm became motile instantaneously at any time when excess cAMP was supplemented. Furthermore, demembranated sperm which were diluted in the reactivating medium containing ATP and cAMP, immediately became motile. cAMP levels in the cell increased during the initiation of sperm motility in both species. These results suggest that cAMP is the real factor indispensable for the initiation of sperm motility at ejaculation in mammals.