Differential fluorescent-banding patterns in chromosomes of four species of Cycas (Gycadaceae)

Similar karyotypes of In = 22 in Cycas circinalis, C. media var. basaltica, C. revoluia var. rewluta, C. revoluta var. taiwaniana and C. siammsis were compared with each other by using the CMA and DAPI fluorescent staining methods. Their four largest submedian-centromeric chromosomes each had a CMA band at the terminal region in common. Their 12 terminal-centromeric chromosomes commonly displayed CMA bands at the terminal region and the pericentric region. Two of the 12 terminal-centromeric chromosomes carried a CMA band somewhere in the interstitial region of the long arm. C. circinalis alone showed it at a relative position closer to the centromere. The other taxa showed it at a relative position near the terminal region. All of the chromosomes exhibited the DAPI dot at the centromeric region.     

Parthenogenetic development of dwarf surf dam,Mulinia lateralis,oocytes treated with polar body suppressing agents

Summary

Parthenogenesis following oocyte activation has been observed in a number of marine invertebrates, but the fate of parthenogenesis in bivalve mollusc embryos is unclear. We used the dwarf surf clam, Mulinia lateralis, to examine parthenogenetic development of KC1-activated oocytes using the polar body suppressing agents caffeine and heat or cytochalasin B. Development was followed by epifluorescence microscopy and flow-cytometric analysis using the DNA-specific fluorochrome DAPI. All agents suppressed polar body formation to some degree, putatively increasing the ploidy level and retaining a meiotic centrosome in the zygote; but the zygotes failed to develop normally. Failure of the zygotes to develop suggests that the meiotic centrosome is incapable of participating in mitosis in bivalves.     

Functional Properties of Cloned Melanogenic Proteins

Several genes critical to the regulation of melanin production in mammals have recently been cloned and characterized. They map to the albino, brown, and slaty loci in mice, and encode proteins with similar structures and features, but with distinct catalytic capacities. The albino locus encodes tyrosinase, an enzyme with three distinct catalytic activities—tyrosine hydroxylase, 3,4-dihydroxyphenylalanine (DOPA) oxidase and DHI (5,6-dihydroxyindole) oxidase. The brown locus encodes TRP-l (tyrosinase-related protein-I), which has the same, but greatly reduced, catalytic potential. The slaty locus encodes TRP-2, another tyrosinase related-protein, which has DOPAchrome tautomerase activity. In this study we have examined the enzymatic interactions of these proteins, and their regulation by a novel melanogenic inhibitor. We observed that tyrosinase activity is more stable in the presence of TRP-l and/or TRP-2, but that the catalytic function of TRP-2 is not affected by the presence of TRP-1 or tyrosinase. Other factors also may influence melanogenesis and a unique melanogenic inhibitor suppresses tyrosinase and DOPAchrome tautomerase activities, but does not affect the spontaneous rate of DOPAchrome decarboxylation to DHI. The results demonstrate the catalytic functions of these proteins and how they stably interact within a melanogenic complex in the melanosome to regulate the quantity and quality of melanin synthesized by the melanocyte.     

Morning dew and Tripospermum (Hyphomycetes)

Morning dew appears to be an important factor in the habitat of Tripospermum species. It affects both conidial development and liberation.     

Neuroendocrine Regulation of the Development of Seasonal Forms of the Asian Comma Butterfly, Polygonia c-aureum L

In the butterfly, Polygonia c-aureum , development of seasonal forms controlled by the photoperiod and temperature was shown to involve a neuroendocrine system of the brain-corpus cardiacum-corpus allatum complex.
For analysis of the neuroendocrine system concerned, the innervation of the complex was investigated first by cobalt chloride perfusion staining and then by severance of axons, ablation of the candidate cells, injection of a homogenate of these cells and transplantation of corpora cardiaca using pupae programmed to be either summer-form or autumn-form adults.
The results suggested that medial nerve cells produce what is called material producing the summer form.
The seasonal forms of the Asian comma butterfly, Polygonia c-aureum L., summer and autumn forms (Fig. la, b), are determined by the photoperiod and the temperature during the larval period (1–3). Previous studies have given the following results on the physiological mechanism involved in the effect of environmental factors in inducing these seasonal forms. First, the mechanism involves neurosecretory cells located somewhere in the brain (2). Second, the nervous connections between the brain and the corpus cardiacum (NCC I+II (4)) and between the right and left brain lobes are indispensable for the effect (2, 5–7).
The present study consisted of two series of experiments. One was designed to demonstrate morphologically the axonal connection of the corpus cardiacum with the corpus allatum in this butterfly, like that shown in several other insects (8–13). The other series was designed to locate the neurosecretory cells producing material related to the seasonal form and to see if this material is also present in the corpus cardiacum.     

Isolation and characterization of microsatellite loci from Quercus mongolica var. crispula

Microsatellites were isolated and characterized for the Japanese oak species, Quercus mongolica var. crispula, distributed in temperate deciduous forests of Japan. Eleven of the 48 primer pairs designed successfully amplified unambiguous and polymorphic single loci among 67 Q. mongolica var. crispula individuals within a plot in southwestern Japan. The observed and expected heterozygosities of the 11 microsatellite markers ranged from 0.522 to 0.896 and from 0.536 to 0.882, respectively. These polymorphic microsatellite markers are useful for estimating pollen‐mediated gene flow in Q. mongolica var. crispula.     

Cypermethrin induction of vitellogenesis and ovarian development in unfed adult female Ornithodoros moubata (Acari: Argasidae)

Summary

Vitellogenesis in ticks is known to be induced by engorgement and mating. In this paper, the synthetic pyrethroid cypermethrin (CyM) is shown to induce production of yolk protein precursor, vitellogenin (Vg), and ovarian development in unengorged mated adult female Ornithodoros moubata. The levels of Vg found in the hemolymph and ovarian development induced by CyM were dose-dependent. i.e., CyM doses of more than 0.2 and 1.0 μg/tick were needed for significant increase of Vg titer in the hemolymph and yolk deposition in oocytes, respectively. Immunological and electrophoretical analyses of Vg and Vitellin (Vn) induced by CyM were identical with those induced by engorgement. Vg titer induced by CyM in unengorged females followed approximately the same time course as that in the normal engorged females. However, Vg titer induced by CyM continued to increase after day 8 and reached a maximum (95 μg/μ1) on day 10 after treatment, while Vg titer induced by engorgement decreased again after reaching a maximum (60 μg/μ1) on day 6, correlated with yolk Vn deposition in oocytes. Ovarian development induced by even high doses (10 or 20 μg/tick) of CyM was slow compared to normal development stimulated by engorgement. Oviposition was not observed in females treated with CyM.     

EFFECT OF TWILIGHT ON PHOTOPERIODIC INDUCTION IN SOME SHORT DAY PLANTS

Light-sensitivity of the first and the last processes in theinductive dark period, and the effect of twilight on photoperiodicinduction were investigated with four short day plants. In Oryza sativa (Akebono), the first and the last processesare relatively light-insensitive, and the photoperiodicallyeffective day length under natural conditions is consideredto be equal to the astronomical day length. In Biloxi soybean and Perilla frutescens, the first processis re latively light-insensitive, but the last process is moresensitive. Effective dark period seems to begin when twilightis 50200 lux in the evening and continue until it is about 10lux in the morning. In Xanthium saccharatum, both the first and the last processesare relatively light-sensitive, but the former is more sensitivethan the latter. Effective dark period seems to begin when twilightis 110 lux in the evening and continue until it is 1050 luxin the morning. ¹Present address: Laboratory of Genetics and Plant Breending,Faculty of Agriculture, University of Osaka Prefecture, Sakai-City,Osaka. (Received February 17, 1961; )