PHYSIOLOGICAL ACTIVITIES OF HELMINTHOSPOROL AND HELMINTHOSPORIC ACID: I. EFFECTS ON GROWTH OF INTACT PLANTS

Helminthosporol (H-ol) and helminthosporic acid (H-acid) wereeffective in promoting elongation of leaf sheaths of rice, Japanesebarnyard grass and dwarf maize (d-2 and d-5) and of hypocotylsof taisai (Brassica chinensis), but inactive in leaf sheathsof oat and wheat, hypocotyls of sesame and morning glory (Pharbitisnil) and epicotyls of Pharbitis and dwarf and tall peas. Onthe elongation of the leaf sheath of maize d-1, H-ol was promotivebut the activity of H-acid was doubtful. On hypocotyls of lettuceand daikon (Raphanus sativus), only H-acid was active. Multiplicationrate and size of fronds of Lemna perpusila were not affectedby either of the substances. Compared with gibberellic acid for the effect on the shoot growth,H-ol and H-acid were weak in activity and narrower in the scopeof plants that responded. H-ol and H-acid characteristicallypromoted the elongation of the primary root. Comparative effectivenessof H-ol and H-acid varied with plant species or parts examined. ¹ This study was supported in part by grant-in aid of the Ministryof Education (No. 0417). The results reported here were presentedat the Annual Meeting of the Botanical Society of Japan at Kanazawain 1964 (S).     

Respiratory nervous activity in the isolated nerve cord of the larval dragonfly, and location of the respiratory oscillator

ABSTRACT. Rhythmic respiratory nerve activity was recorded in the dragonfly larvae, Anax parthenope Julius Brauer (Anisoptera). Alternating expiratory and inspiratory bursts of spikes occurred in abdominal nerve cords isolated from all peripheral connections. These bursts are similar to the activity recorded in semi-intact preparations, suggesting that the respiratory rhythm can be generated without peripheral sensory feedback. Expiratory bursts started and ended at the same time in different segments of semi-intact preparations. When connectives were severed, the nerve cord separated from the last abdominal ganglion did not normally show rhythmic bursts; the last ganglion alone and the nerve cord connected to the last ganglion exhibited the rhythmic bursts. However, in a few cases the nerve cord separated from the last ganglion exhibited the rhythm. The results suggest that the last ganglion contains the main oscillator, but that other weak oscillators occur elsewhere.     

A comparative study on insemination dependency of circadian activity pattern in mosquitoes

Abstract. Two forms of mosquitoes in the Culex pipiens complex, C.p.pallens and C.p.molestus , were compared for the insemination-dependency of entrained female circadian activity in LD 16:8h. When virgin, Pallens is nocturnal and molestus is, in addition, diurnal. Insemination and injection of extracts of the male accessory gland affects virgin activity in that nocturnality is strengthened in both mosquitoes, and the diurnal activity of molestus is depressed. This was so whether the treatments were intra- or interspecific. These findings are compared with those already published for other mosquitoes. A coherent view is proposed that the mosquito, nocturnal/crepuscular, nocturnal and diurnal, or diurnal, has potentially a similar entrained waveform which is affected by insemination in a common way, and by lighting conditions in species specific ways.     

Sensory Responses of Reinnervated Muscle Spindles

EXTENSIVE morphological, histochemical and electrophysiological studies have been made on skeletal muscles at varying stages of motor reinnervation. But in spite of the physiological significance of muscle receptors in controlling skeletal muscle activity, there have been no detailed studies of their reinnervation. We have therefore investigated the functional and structural characteristics of muscle spindles associated with their sensory reinnervation.     

Extraorgan freezing in wintering flower buds of Cornus officinalis Sieb. et Zucc.

Abstract. Extraorgan freezing as a mechanism for increasing cold hardiness was shown using flower buds of Cornus officinalis Sieb. et Zucc. Differential thermal analysis (DTA) revealed that florets in flower buds of C. officinalis owed their cold hardiness to deep supercooling and also that slower cooling rates increased the supercooling ability of florets. During slow stepwise cooling (5°C h⁻¹), the water content of florets decreased and that of scales (involucral bracts) increased, which resulted in accumulation of ice within the scales. This was more extensive in early winter and early spring buds than mid-winter ones. Flower buds with silicone oil in the space between florets and scales also showed a similar decrease in water content of florets and an increase in that of scales. This indicated that water migration from the florets to the scales probably took place by way of the peduncles and the receptacle, possibly through their vascular traces, and not directly from the surface of the florets to the ice sink in the form of vapour. Possible mechanisms of extraorgan freezing are postulated along with this finding.     

FUNCTIONS OF CALCIUM IN THE CELL WALL OF RICE LEAVES

Rice plants were grown in nutrient solutions containing 0.5,20, and 500 ppm of calcium as CaO. Microscopic observation revealedthat the mesophyll structure in the leaves was disordered atthe lowest Ca level and became healthy with increasing supplyof calcium in the culture solution. The chemical constitutionof cell wall and the composition of sugar in each chemical constituentof wall differed little among the leaves grown with differentlevels of calcium. The calcium contents in the walls of calciumdeficient leaves were extremely low as compared with those ofnormal leaves. The amount of calcium extractable in the ligninfraction of Ca 0.5 leaves was only about one-sixth of that ofCa 500 leaves. Furthermore, calcium in the lignin fraction wasleached out by treating the wall previously with 2% acetic acidsolution. These results suggest a close association of calciumwith ligneous substances in combined forms of physiologicalimportance in the cell walls. (Received April 11, 1967; )     

Crystalline Ferredoxin from a Blue-Green Alga, Nostoc sp.

Ferredoxin isolated from a blue-green alga, Nostoc sp., was purified and crystallized. The absorption spectrum of Nostoc ferredoxin had, in the oxidized state, peaks at 276, 331, 423, and 470 nm, a pattern characteristic of chloroplast-type ferredoxin. The 423:276 absorption ratio was 0.57. The midpoint oxidation-reduction potential of Nostoc ferredoxin was found to be –406 mV, at pH 7.5. Nostoc ferredoxin mediated the photoreduction of NADP by isolated Nostoc chromato-phores and spinach chloroplasts from which the native ferredoxin was removed. The molar ratio of Nostoc ferredoxin to chlorophyll a was about 1:50, a ratio higher than usually found in photosynthetic cells. The possible evolutionary significance of the properties of Nostoc ferredoxin compared with those of ferredoxins from other photosynthetic organisms is discussed.     

Electron Microscopic Analysis of Phagocytic Activity of Chick Embryonic Retinal pigment cells in vitro

The phagocytosis of latex particles by retinal pigmented cells from chick embryos was studied in vitro. The pigment epithelial cells phagocytized latex particles within 2 hr without a latent period, as found in some mamalian species. The number of latex phagosomes increased with time, and the phagosomes eventually became distributed nearly uniformly in the cytoplasm. When cultures that had been exposed to latex particles for 24 hr were incubated without the particles for a further 7 days, numerous latex phagosomes remained inside the cells without any decrease in their number. This indicates that phagocytized particles are not ejected from the cells, presumably due to a defect in, or absence of, exocytotic activity.     

IMMUNOHISTOCHEMICAL DETECTION OF VITELLOGENIN IN THE OVARY AND FAT BODY DURING A REPRODUCTIVE CYCLE OF THE COCKROACH, BLATTELLA GERMANICA

Vitellogenin was immunohistochemically demonstrated in the ovary and fat body during a reproductive cycle. In terminal oocytes of 4-day adults, vitellogenin began to appear in yolk spherules at the cell periphery. The vitellogenin-containing spherules increased in size and number to occupy the whole cell 2 days later. In the female fat body, vitellogenin began to appear in 3-day adults. It was distributed diffusely in the cytoplasm, at a much lower concentration than in the oocytes, during the vitellogenic period. In 11-day adults whose vitellogenesis had terminated, a higher concentration of vitellogenin was found in the cytoplasmic inclusions of the fat body. Vitellogenin was not detected in the male fat body.