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  • Author: S. Abe x
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Abstract

Five species of the red algal order Ceramiales are reported from Malaysia for the first time, and their characteristic features are described: three species of Hypoglossum (Delesseriaceae), H. rhizophorum Ballantine et Wynne, H. caloglossoides Wynne et Kraft and H. simulans Wynne, Price et Ballantine, and two species of Rhodomelaceae, Laurencia caduciramulosa Masuda et Kawaguchi and Neosiphonia savatieri (Hariot) M. S. Kim et I. K. Lee. Small deciduous branchlets of Laurencia caduciramulosa are documented to be genuine propagules.

Abstract

The following five species of marine red algae are reported from Malaysia for the first time and their characteristic features are described: Cryptonemia yendoi Weber-van Bosse (Halymeniaceae, Cryptonemiales), Caulacanthus ustulatus (Turner) Kützing (Caulacanthaceae, Gigartinales), Chondracanthus intermedius (Suringar) Hommersand (Gigartinaceae, Gigartinales), Griffithsia schousboei Montagne (Ceramiaceae, Ceramiales) and Laurencia flexilis Setchell (Rhodomelaceae, Ceramiales). The presence of Anotrichium tenue (C. Agardh) Nägeli (Ceramiaceae, Ceramiales) in Malaysia is confirmed. Chondracanthus okamurae Abbott, originally described from Japan, is reduced to the synonymy of C. intermedius.

Abstract

Apyrase (ATP diphosphohydrolase, EC 3.6.1.5) catalyzes hydrolysis of nucleoside tri- and di-phosphates to nucleoside monophosphates and orthophosphates. In the present study, the spatio-temporal expression of an apyrase gene (PsAPY1) in pea (Pisum sativum L. var. Alaska), was investigated during early stages of apical hook development using nonradioactive mRNA in-situ hybridization. During the formation of apical hook; at 45 hours after sowing (HAS), expression of PsAPY1 was obvious in epidermis and vascular bundle. By 60 HAS, the apical hook was completely formed. At this stage, transcript accumulation became higher than at the previous stage and expression was also visible in the cortex tissues of the developing hook. However, at 78 HAS, the curvature of the hook was reduced and hook was in the process of opening. At this time, expression of PsAPY1 was visible in all the above-mentioned tissues although the level of expression was slightly lower than at the previous stage (60 HAS). Apical hook formation provides a unique mechanism of protection for delicate shoot meristem in dicot plants. Its establishment is orchestrated by differential elongation rates of cells within the structure. The expression pattern of a gene provides essential information concerning the likely appearance and localization of its encoded protein and this helps to understand the mechanism of development of plant cells and tissues. Higher expression of PsAPY1 during the process of hook development indicates its essential role in the process of formation and maintenance of hook curvature and thus aids in protection of delicate shoot meristem.

Abstract

Photosynthetic activities of submerged seaweeds before and after drying were measured in eighteen species collected from different vertical positions from a Pacific shore at Shimoda City in Japan. The seaweeds were desiccated until the cellular water levels equilibrated with the air in the chamber under various humidities at 10 °C. Relative water contents of all species drastically decreased as the cellular water potentials were reduced from 0 to −14MPa and gradually decreased in the range from −14 to −158MPa. Porphyra dentata, which is an upper intertidal species, recovered photosynthetic activity from the lowermost water potential of −158MPa, while the plants collected from the lower intertidal and subtidal zones reduced their photosynthetic activities after desiccation to comparatively higher water potentials from 0 to −14MPa. Other species collected from the middle intertidal zone reduced their photosynthetic activities following desiccation to water potentials in the range from −14 to −158MPa. It is concluded that the cellular abilities of desiccation tolerance in intertidal seaweeds varied between the species examined and correlated with their vertical position within the tidal zone.

Abstract

The spin-lattice relaxation time, T1, of the 23Na-NMR line in NaNO2 is measured between 25 K and 160 K at two magnetic field strengths, 1.1 T and 6.9 T. The temperature dependence of T1 for the center line, observed on a polycrystalline sample prepared by precipitation from aqueous solution, is given by a monotonous curve. T1 increases gradually as the temperature decreases. On the other hand for a single crystal, which is made by a modified Bridgman method, the temperature dependence of T1 shows two deep dips below 150 K and a frequency dependence which cannot be explained by ordinary BPP theory.

The dominant relaxation mechanism above and below 150 K is also investigated.