The ribosomal RNA genes from chloroplasts of mustard (Sinapis alba L.): mapping and sequencing of the leader region

Summary The genes coding for rRNAs from mustard chloroplasts were mapped within the inverted repeat regions of intact ctDNA and on ctDNA fragments cloned in pBR322. R-loop analysis and restriction endonuclease mapping show that the genes for 16S rRNA map at distances of 17 kb from the junctions of the repeat regions with the large unique region. The genes for 23S rRNA are located at distances of 2.8 kb from the junctions with the small unique region. Genes for 4.5S and 5S rRNA are located in close proximity to the 23S rRNA genes towards the small unique region. DNA sequencing of portions of the 5 terminal third from the mustard 16S rRNA gene shows 96–99% homology with the corresponding regions of the maize, tobacco and spinach chloroplast genes. Sequencing of the region proximal to the 16S rRNA gene reveals the presence of a tRNA^Val gene in nearly the same position and with identical sequence as in maize, tobacco and spinach. Somewhat less but still strong homology is also observed for the tDNA ^Val/16S rDNA intercistronic regions and for the regions upstream of the tRNA^Val gene. However, due to many small and also a few larger deletions and insertions in the leader region, common reading frames coding for homologous peptides larger than 44 amino acids can not be detected; it is therefore unlikely that this region contains a protein coding gene.     

Relationship between secondary constrictions and nucleolus organizing regions inAllium sativum chromosomes

Summary Allium sativum L. (2 n=16) had three types of clones with regard to the number of chromosomes carrying well-defined secondary constrictions: the first type had two secondary constricted chromosomes (type I), the second had three (type II) and the third had four (type III). Silver staining was applied to these three types of cells to determine the number of nucleolus organizing regions (NORs) per cell and to study the relationship between the morphological appearance of the secondary constrictions and the ability of the chromosomes to form nucleoli. Ag-positive regions appeared on two chromosomes in type I, on three in type II and on four in type III. The comparison of Giemsa and Feulgen stained chromosomes with the silver stained ones clearly indicated that the positive reaction with silver occurred exclusively on the secondary constricted regions that responded negatively to both Giemsa and Feulgen staining, indicating that the size of the achromatic secondary constrictions directly reflects the volume of the Ag-positive materials. However, all three types of clones had a maximum of four nucleoli at interphase. Of the four nucleoli, either two or one was extremely small (less than 1 m in diameter) in types I and II respectively. The size variations of the other nucleoli seemed to be positively correlated with those of the Ag-positive regions. This and the observation that the maximum number of nucleoli per cell did not coincide with the number of Ag-positive regions on the metaphase chromosome complement suggest strongly that the NORs responsible for the minute nucleoli cannot be detected on the metaphase chromosomes. The present observations indicate that not all NORs are indicated by the morphological appearance of secondary constrictions.     

The use of specific lysine modifications to locate the reaction site of cytochrome c with sulfite oxidase

The reduction of cytochrome c by beef liver sulfite oxidase was found to be strongly inhibited by high ionic strength, indicating the importance of electrostatic interactions to the reaction. The reaction rates of sulfite oxidase with singly trifluoroacetylated or trifluoromethylphenylcarbamylated cytochrome c derivatives were studied to determine the role of individual lysines in the reaction. The reaction rate was decreased by modification of the lysines immediately surrounding the heme crevice, the decreases following the order: Lys 13 > Lys 25 Lys 79 ≈ Lys 87 > Lys 8 ≈ Lys 27 ≈ Lys 72. Modification of lysines 22, 55, 88, 99, and 100 had no effect on the reaction rate. These results indicate that the interaction site on cytochrome c for sulfite oxidase is at the heme crevice region, and overlaps considerable with that for cytochrome oxidase.     

Fine structure of the ‘Wulst’ region of the domestic fowl in organotypic cultures

Summary Parts of the Wulst region of the chick embryo brain were maintained for 39 days in vitro. Processes of adjacent glial cell form zonulae occludentes and desmosomal junctions in the uppermost stratum of the cultures. Subjacent to this layer, in the neuropil, axodendritic synapses are abundant. 10–20 m below the surface the perikarya of glial cells and neurons are found. The latter form small clusters, plasma membranes of contiguous cells being directly apposed to each other. Axosomatic synapses terminate on the perikarya. Occasionally one terminal synapses on two nerve cells simultaneously. Two types of cilia arise from basal bodies in the cytoplasm of nerve cells. Type I is a slender protrusion of about 0.5 m in diameter, extending into the neuropil. On transverse sections it displays a 9 + 0 pattern of organization of paired micro tubules proximally, and an 8 + 1 configuration more distally. The length of the cilium is approximately 7 m. Type II cilia also originate in the neuronal cytoplasm. The structure of the proximal portion is identical with that of type I cilia. Toward the tip, however, the type II cilium is characterized by a bulbous enlargement which is filled with loosely folded membranes. The fine structural details of this cilium correlate closely to the outer segments of retinal photoreceptor cells during differentiation. The possible role of a light receptor in the Wulst region of birds, controlling biological rhythms, is discussed. Acknowledgements. The authors wish to thank Mrs. H. Frenk for her expert assistance in tissue culture and electron microscopic techniques     

中国蜘蛛抱蛋属一新记录种——博格纳蜘蛛抱蛋

报道了产自中国云南喀斯特地区的蜘蛛抱蛋属一新记录种——博格纳蜘蛛抱蛋（Aspidistra bogneri H.-J.Tillich）。该种以前报道仅产于越南宁平省菊芳国家公园（Ninh Binh,Cuc Phuong National Park）,本次是中国首次记录。对该种的特征进行了详细描述并提供了彩色图片,凭证标本存放于中国科学院昆明植物研究所标本馆（KUN）。     

深圳市西海岸和海域生物资源多样性的管护

本文着重介绍生物多样性管护区的基本含义和要求,结合深圳市西海岸和海域的特点,提出建立珠江口南海海岸和海洋生物多样性管护区,以发挥该区域的资源优势和持续利用,为建设深圳特区做出应有的贡献。     

Dynamic sweating response of man to infrared irradiation in various spectral regions

In an attempt to detect differences in the thermal effect of infrared irradiation of different wavelengths, transient sweating response to infrared irradiation in various spectral regions was examined. In Series 1, the ventral or dorsal surface of the nude subject was irradiated repetitively for a period of 4 min (2 min on, 2 min off) by each of three kinds of infrared heaters with main emissivity in near-infrared (NIR; 0.7–2.8 m), intermediate-infrared (MIR; 1.5–5.8 m), and far-infrared (FIR; 2.8–25 m) regions. The sweating response on a non-irradiated area tended to be the greatest with MIR, while the magnitude of the sweating response on the irradiated area showed no consistent differences among various wavelengths. The results infer that MIR stimulated cutaneous thomoreceptors most effectively, while its direct effect on local sweat gland activity was minimal. In Series 2, the effects of 9–12 min irradiations in more restricted ranges of wavelength were compared by the combination of the three kinds of heaters with filters (translucent to wavelength ranges of 1.3–2.7, 2.7–3.5, 3.6–8.0 m, respectively). The sweating response on a remote area was predominantly greater with the range of 2.7–3.5 m than with the other wavelength ranges, while the local effect on sweating was minimal with this range. The results of Series 2 reinforce those of Series 1, indicating that the degree of stimulation of cutaneous thermoreceptors and of direct thermal effect on sweat gland activity differ with spectral regions incident on the skin, thus affecting local and remote effects on the sweating response.