Early development of the laboratory-reared flounder,Pleuronichthys cornutus

Fertilized eggs ofPleuronichthys cornutus were obtained by both artificial fertilization and natural spawning of laboratory-reared fish. The present paper describes in detail the early development of the fish and the rearing methods employed to provide basic information for mass production of this species. Eggs and sperm for artificial fertilization were obtained from adult fish caught in the Ariake Sound, Kyushu in November and December of 1984. Their maturation was successfully induced by intermuscular injection of pituitary homogenate of the silver carp,Hypophthalmichthys molitrix. Fertilized eggs were also obtained in 1985 by natural spawning of a broodstock kept in a tank for a year. Hatched larvae were fed successively with rotifers,Artemia nauplii and the harpacticoid copepod,Tigriopus japonicus and reared for 80 days. Ten thousand young fish of about 33 mm TL were obtained in 1984 and 1985 with the survival rate of about 17%. Ten developmental stages were defined on the basis of the morphological characteristics: A) newly hatched to 4 day old larvae, 2.7 to 4.1 mm TL (2.6 to 3.9 mmNL), yolk sac present; B) 4 to 16 day old larvae, 3.8 to 5.9 mm (3.6 to 5.6 mm), yolk resorbed, actively feeding on rotifers; C) 15 to 30 day old larvae, 6.3 to 8.3 mm (6.0 to 7.9 mm), notochord straight, hypural fin ray visible; D) 24 to 40 day old larvae, 6.7 to 9.2 mm (6.4 to 8.8 mm), caudal notochord upturned (45°); E) 28 to 45 day old larvae, 7.9 to 10.8 mm (7.5 to 10.3 mm), caudal notochord upturned (45°–90°); F) 32 to 50 day old larvae, 10.8 to 15.7 mm (8.8 to 12.8 mm BL), eyes symmetrical; G) 35 to 66 day old larvae, 13.4 to 20.0 mm (10.9 to 16.3 mm), eyes asymmetrical, but left eye not visible from the right side; H) 40 to 75 day old larvae, 13.8 to 26.2 mm (11.3 to 21.4 mm), the upper edge of left eye visible over top of the head from the right side; I) 46 to 89 day old larvae, 20.1 to 27.4 mm (16.4 to 22.4mm), left eye on the edge of the head and pupil visible from the right side; and J) juveniles of 51 day old or over, 23.6 mm or more (19.3 mm or more), metamorphosis completed. One to three inflections were found for relative growth of total length, eye diameter, upper jaw length, preanal length, and distance between the base of the pectoral fin and the anus against the notochord length or body length. Two inflections were found for body length (or notochord length)-body weight relationship. Most inflections appeared at the stages of D, F and J, corresponding to the body length of 8, 9–12 and 18–22 mm respectively.     

Light Activation of NADP-Malate Dehydrogenase in Guard Cell Protoplasts from Vicia faba L

Light-induced swelling of guard cell protoplasts (GCP) from Vicia faba was accompanied by increases in content of K⁺ and malate. DCMU inhibited the increase of K⁺ and malate, and consequently swelling.

Effect of light on the activity of selected enzymes that take part in malate formation was studied. When isolated GCP were illuminated, NADP-malate dehydrogenase (NADP-MDH) was activated, and the activity reached a maximum within 5 minutes. The enzyme activity underwent 5- to 6-fold increase in the light. Upon turning off the light, the enzyme was inactivated in 5 minutes NAD-MDH and phosphoenolpyruvate carboxylase (PEPC) were not influenced by light. The rapid light activation of NADP-MDH was inhibited by DCMU, suggesting that the enzyme was activated by reductants from the linear electron transport in chloroplasts. An enzyme localization study by differential centrifugation indicates that NADP-MDH is located in the chloroplasts, NAD-MDH in the cytosol and mitochondria, and PEPC in the cytosol. After light activation, the activity of NADP-MDH in guard cells was 10 times that in mesophyll cells on a chlorophyll basis. The physiological significance of light-dependent activation of NADP-MDH in guard cells is discussed in relation to stomatal movement.

     

Methylation analysis of extracellular polysaccharides from suspension-cultured cells of Nicotiana tabacum

The soluble extracellular polysaccharides (ECP) of suspension-cultured tobacco cells were fractionated by DEAE-Sephadex CC into seven sub-fractions. Su     

Functional morphology of Gené's organ inHaemaphysalis longicornis (Acari: Ixodidae)

The structure and function of Gené's organ, which secretes the egg wax, were investigated inHaemaphysalis longicornis. The hatching rates of eggs deposited before and after the prevention of the eversion of Gené's organ were compared at the conditions of 30°C, 100% RH and soaking in liquid paraffin. The movement of Gené's organ was observed, and the structures of this organ in unfed and ovipositing females were examined with both light and scanning electron microscopes.The hatching rates of eggs without contact with Gené's organ were markedly lower (4.9%) than that of normal eggs (94.5%) even at the suitable condition for eggs (30°C, 100% RH). In contrast, the hatching rates of eggs soaked in liquid paraffin without contact of Gené's organ were considerably higher (71.8%) than that of eggs without both Gené's organ contact and soaking in liquid paraffin.When oviposition commenced, the camerostome of the female was widened by a downswing of the capitulum, the paired horns of Gené's organ emerged through it, and the oviposited egg from the genital aperture was coated with egg wax. At the same time of retraction of the horns which grip an egg, the capitulum was swung up and the egg was loaded on the scutum.Gené's organ included the outer and inner cuticles, and the outer one is highly folded like bellows when the horns of this organ were retracted into the haemocoel. The undeveloped glands lying in the peripheral region of Gené's organ in the unfed stage commenced their enlargement at the time of the onset of feeding, and they became large tubular glands in the 1-day ovipositing female. The columnar glandular cells of the tubular glands extended their domed apical region into the lumen and contained numerous secretory granules during oviposition.These results suggest that the tubular glands secrete the egg wax which is indispensable for egg survival by serving as a waterproofing agent.     

Changes in endogenous cytokinin levels in partially synchronized cultured tobacco cells

During the course of partially synchronized cell divisions in cultured tobacco (Xanthi) cells the amount of endogenous cytokinins in the butanol-soluble fraction increased 5 to 10 times in 3 hours and paralleled the increase in frequency of mitosis. Among three cytokinins detected in tobacco cells, the activity corresponding to the R_F of authentic zeatin in thin layer chromatography changed in parallel with the mitotic index.     

Formation of hypsorhodopsin in frog retina

Hypsorhodopsin was formed in frog retina by irradiation at liquid helium temperature and converted into bathorhodopsin above about 29 K.     

Mathematical analysis of the mutarotation of sugars

The tautomerism of sugars showing complex mutarotation has been analyzed mathematically based on a scheme of three components. More-complete but complex schemes are shown to be reducible to the three-component scheme, because the supposed intermediates of interconversion can be neglected in the kinetics when their equilibrium contents are very small and because two furanose tautomers can be regarded as one component under appropriate conditions. The kinetics of the three-component scheme have been fully studied and are shown to explain successfully the tautomerism of most of the sugars. The tautomerism of D-galactose has been analyzed in especial detail. From the polarimetric data and the equilibrium content of α-pyranose, the kinetic rate-constants for D-galactose were determined and found consistent with all other experimental data. The slow and fast processes of complex mutarotation of D-galactose are shown to correspond approximately to pyranose-pyranose and pyranose-furanose interconversions, respectively.     

Studies on protein folding, unfolding and fluctuations by computer simulation. I. The effect of specific amino acid sequence represented by specific inter-unit interactions.

A lattice model of proteins is introduced. "A protein molecule" is a chain of nown-intersecting units of a given length on the two-dimensional square lattice. The copolymeric character of protein molecules is incorporated into the model in the form of specificities of inter-unit interactions. This model proved most effective for studying the statistical mechanical characteristics of protein folding, unfolding and fluctuations. The specificities of inter-unit interactions are shown to be the primary factors responsible for the all-or-none type transition from native to denatured states of globular proteins. The model has been studied by the Monte Carlo method of Metropolis et al., which is now shown applied to approximately simulating a kinetic process. In the strong limit of the specificity of the inter-unit interaction the native conformation was reached in this method by starting from an extended conformation. The possible generalization and application of this method for finding the native conformation of proteins form their amino sequence are discussed.     

Purification and Some Properties of Nucleases from Shii-take,Lentinus edodes

Three kinds of nuclease preparations, each of which having both endonuclease activity that formed 5′-mononucleotides and 3′-nucleotidase activity, were separated and partially purified from Shii-take, Lentinus edodes. Both enzyme activities of each preparation showed a similar thermostability and electrophoretic mobility on Polyacrylamide gel, and a competitive relationship was observed between RNA and 3′-AMP in their enzyme reactions. From these results, it is concluded that both enzyme activities of these three preparations reside in a single protein, respectively. They resemble one another in substrate specificity, cleavage pattern of RNA and thermostability, but are distinguishable from one another by molecular weight, electrophoretic mobility and optimum pH for degradation of RNA.