Photoregulated or Energy Dependent Process of Hormogonia Differentiation in Nostoc sphaeroides Kutzing （Cyanobacterium）

Abstract: Hormogonium, which was thought to play an important role in the dispersal and survival of these microorganisms in their natural habitats, is a distinguishable developmental stage of heterocystous cyanobacteria. The present study examined the effects of different light conditions and sugars on the differentiation of Nostoc sphaeroides Kützing to the hormogonia stage. Results showed that differentiation of hormogonia was light dependent in the absence of sugar, but that close to 100% of cyanobacteria differentiated to hormogonia in the presence of glucose or sucrose, irrespective of the light conditions. This differentiation was inhibited, even in the presence of sugars, upon application of an inhibitor of respiration. Following the testing of different sugars, the effects of different lights were examined. It was found that 5–10 umol‐nT2‐s‐1 photon flux density was optimal for hormogonia differentiation. One hundred percent differentiation was obtained with white light irradiation, in contrast with irradiation with green light (80% differentiation) and red light (0–10% differentiation). Although they showed different efficiencies in inducing hormogonia differentiation in N. sphaeroides, the green and red radiation did not display antagonistic effects. When the additional aspect of time dependence was investigated through the application of different light radiations and an inhibitor of protein synthesis, it was found that the initial 6 h of the differentiation process was crucial for hormogonia differentiation. Taken together, these results show that hormogonia differentiation in N. sphaeroides is either a photoregulated or an energy dependent process. (Managing editor: Ping HE)     

中国薹草属(莎草科)研究随记(Ⅳ).隐匿薹草组的分类修订(英文)

隐匿薹草组(Carex sect.Infossae)为最近建立的薹草属(Carex)的组,当时报导分布于我国安徽和江苏,有2种和1变种,即隐匿薹草(C.infossa)、显穗薹草(变种)(C.infossa var.extensa)和矮秆薹草(C.minuticulmis)。根据描述,另有15种和2变种应归属本组,这些分类群具有较为一致的特征:果囊椭圆球状卵球形或卵球形,通常疏被短毛或近无毛,先端渐狭成中等长的喙,喙口具2小齿;瘦果卵球形,先端钝或微凹。通过文献考证、标本查阅、野外采集,并结合果囊和瘦果的扫描电镜观察,对隐匿薹草组所涉及的种(含种下类群)进行了分类修订。该组仅有2种:百里薹草(C.blinii)和尖叶薹草(C.oxyphylla)。将Carex elmeri、C.granifera、矮秆薹草(C.minuticulmis)、上海薹草(C.shanghaiensis C.blinii subsp.shanghaiensis)、C.sublateralis、C.taihokuensis和锐果薹草(C.tatsutakensis)并入百里薹草;将沟囊薹草(C.canaliculata)、樟木薹草(C.changmuensis)、C.distantiflora、隐匿薹草(C.infossa)、显穗薹草(C.infossa var.extensa)、C.lateralis、C.loheri、无芒长嘴薹草(C.longerostrata var.exaristata)、城湾薹草(C.longerostrata var.hoi)、C.lyi、和平菱果薹草(C.macrandrolepis)和C.sharyotensis并入尖叶薹草。     

Anatomical and chemical characteristics of the seed coat of <i>Medicago sativa</i> L. (alfalfa) cv. Baralfa 85 seeds and their association with seed dormancy

Seeds of alfalfa (Medicago sativa L.) can exhibit seedcoat imposed dormancy, which produces hard seeds within a seed lot. These seeds do not germinate because they do not imbibe water due to a barrier to water entry in the seed coat. The aim of this work was to analyze the anatomical and chemical characteristics of the testa of alfalfa seeds with respect to water permeability levels. The anatomy of seeds of the cv. Baralfa 85 was studied and structural substances, polyphenols, tannins and cutin present in the testa of seeds of different water permeability levels were determined. The anatomical characteristics of the seed coat and the proportions of components were found to determine the permeability level of the seed coat, an aspect that is associated with the physical seed dormancy level. Anatomically, increased thickness of the testa was associated with a lower permeability level. The difference may be attributed to the variation in cuticle thickness, length of macrosclereids and thickness of the cell wall, and presence and development of osteosclereids. From the physiological and chemical points of view, the mechanism of physical dormancy of the testa is explained by a greater amount of components that repel water and cement the cell wall, such as polyphenols, lignins, condensed tannins, pectic substances, and a lower proportion of cellulose and hemicellulose.     

Revision of the family Carabodidae (Acari,Oribatida) V. Fourth part. Two new species of the genus Congocepheus from the Republic of Rwanda: Congocepheus rwandensis sp. n., and Congocepheus kayoveae sp. n.

Two new species from Rwanda are described utilizing optical and scanning electron microscope observations: Congocepheus rwandensis sp. n. and Congocepheus kayoveae sp. n. are compared to Congocepheus taurus Balogh 1961.     

Chemical differentiation between leaves of seedlings and spatially close adult trees from the tropical rain-forest species Nectandra ambigens (Lauraceae): an alternative test of the Janzen–Connell model

1. We tested the hypothesis of Langenheim and Stubblebine that differences in chemical composition between maternal trees and the seedlings under them arise from differential mortality; only seedlings different from the mother survive. Such mortality could explain at least some of the cases where seedlings accumulate under adult conspecifics, contrary to the extreme form of the Janzen–Connell hypothesis.
2. We investigated Nectandra ambigens (Lauraceae), an upper-canopy tree at Los Tuxtlas tropical rain forest, Mexico, whose seedlings survive under the canopy of conspecific trees. We analysed chromatographic profiles of leaf terpenoids of 15 groups, each formed by an adult tree and its surrounding seedlings.
3. We predicted that seedlings chemically similar to the adult would be absent under the tree canopy and that they would be present outside that canopy. We also predicted that younger seedlings would be more similar to the adult than the older ones.
4. Chemical similarity analyses showed that most seedlings were significantly different from their closest adult and thus supported the Langenheim and Stubblebine hypothesis. However, we did not find chemical differentiation among seedlings regarding their age or their position inside or outside the tree canopy.     

EPR Spectrum at 4, 9 and 35 GHz of hydrogenase from Chromatium vinosum. Direct evidence for spin-spin interaction between Ni(III) and the ironsulphur cluster

EPR spectra at 4, 9 and 35 GHz of hydrogenase isolated from Chromatium vinosum have been compared. The spectra at 4 and 35 GHz confirmed our earlier conclusions, made from observations at 9 GHz (Albracht, S.P.J., Kalkman, M.L. and Slater, E.C. (1983) Biochim. Biophys. Acta 724, 309–316), that the irreversibly inactivated enzyme molecules in the preparation give rise to two EPR signals due to the independent non-interacting $\text{S =}\text{1}\text{2}$ systems of Ni(III) and a |3Fe-xS| cluster. It was observed that intact enzyme molecules show a complex EPR spectrum caused by a spin-coupled pair of Ni(III) and a |4Fe-4S|³⁺ cluster. The interaction energy is so weak (approx. 0.01 cm^?1) that the 35 GHz spectra of both the Ni(III) and the |4Fe-4S|³⁺ cluster have the appearance of rather normal $\text{S =}\text{1}\text{2}$ spectra with additional splittings as a result of the spin-spin interaction. At lower microwave frequencies, the spectra become increasingly complex but phenomenologically they behave as expected for an exchange-coupled pair of dissimilar ions. The distance between the two spin systems is estimated to be at the most 1.2 nm. The spin-relaxation rate of the Ni(III) ion is dramatically enhanced as a result of the coupling to the rapidly relaxing Fe-S cluster. The g values and so presumably also the ligand fields of Ni in intact and irreversibly inactivated enzyme molecules are identical. This suggests that the specific coordination of the nickel in the enzyme is not the only requirement for activity with artificial electron donors or acceptors, and that the presence of a nearby, intact |4Fe-4S|^3+(3+,2+) cluster might be another essential factor. From the g values and the probable function of Ni in the enzyme we propose, as a working hypothesis, that the nickel ion has five ligands provided by the protein in a square-pyramidal coordination.     

Concentrations of the Active Constituents of the Tibetan Folk Medicine Qinjiao (Gentiana sect. Cruciata) within and between Taxonomic Species across the Qinghai‐Tibetan Plateau

The Tibetan folk medicine Qinjiao is traditionally used to treat various conditions, and its main active constituents comprise four iridoid glycosides, i.e., loganic acid, swertiamarin, gentiopicroside, and sweroside. The traditional crude medicine Qinjiao is derived from the dried roots of three species belonging to Gentiana sect. Cruciata (Gentianaceae) growing in the Qinghai‐Tibetan Plateau (QTP). In this study, we determined by HPLC the contents of the four main active constituents in the dried roots collected from 83 localities at different altitudes across the QTP. The material was classified under the seven taxonomic species G. straminea, G. dahurica, G. crassicaulis, G. waltonii, G. officinalis, G. ihassica, and G. macrophylla. Our results suggested that the four constituents were present in the roots of all seven species for all localities, but their concentrations varied greatly within and between species. The level of gentiopicroside revealed to be the most dominant for all examined localities (2.1–12.4 mg/g), and G. macrophylla Pall . contained the highest concentration of all the four constituents at the species level. Except for loganic acid in G. officinalis, there was no significant correlation between the contents of these constituents and the altitude of the sampling localities. These results suggest that all species of all origins can be used as reliable resource for the crude medicine Qinjiao. However, a few species contain higher concentrations of the main active constituents, irrespective of their origin.     

Physiological comparison of copper toxicity in the lichens <Emphasis Type="Italic">Peltigera rufescens</Emphasis> (Weis) Humb. and <Emphasis Type="Italic">Cladina arbuscula</Emphasis> subsp. <Emphasis Type="Italic">mitis</Emphasis> (Sandst.) Ruoss

Peltigera rufescens (Weis) Humb. with a prokaryotic photobiont Nostoc sp. and Cladina arbuscula subsp. mitis (Sandst.) Ruoss with a eukaryotic photobiont Trebouxia sp. were studied to determine the copper sensitivity of lichens with different algal symbionts. Samples growing on historic copper mine-spoil heaps at Ľubietová–Podlipa, Slovakia were assessed for physiological parameters, including total and intracellular uptake of copper, assimilation pigmentation, activity of photosystem II, ergosterol levels, thiobarbituric acid reactive substances and water-soluble protein content. Our results indicate that P. rufescens was more sensitive to copper exposure than C. arbuscula subsp. mitis.     

Evaluation of the efficacy of mitochondrial ATP 6 and 8, Cyt b and 16S rDNA genes for differentiation of Iranian honeybees (Apis mellifera meda) from commercial subspecies of Apis mellifera L. and comparison with geometric morphometric method

Mitochondrial DNA sequence variations and the geometric morphometric method can be used to differentiate honeybee subspecies and evolutionary lineages. Molecular markers are powerful tools for discriminating honeybee subspecies. In this study, 19 beekeeping sites were selected to collect Iranian honeybee samples. The honeybee forewing images stored at Oberursel (the Bee Data Bank) were used to compare with those of Iranian honeybees using the geometric morphometric method. Furthermore, the abilities of DNA markers to differentiate Iranian honeybees (A. m. meda) from the most common commercial subspecies (A. m. carnica and A. m. ligustica) were assessed. In the present research, 16S rDNA (Mitochondrial 16S rDNA Region) showed greater ability in differentiating Iranian honeybees from other subspecies compared with ATP 6 and 8 and Cyt b. The phylogenetic tree derived from 16S rDNA differentiated A. m. carnica and A. m. ligustica from Iranian honeybees. Principle component analysis (PCA) discriminated C lineage and Z subgroup from A and M lineages using 16S rDNA. In addition, the phylogenetic tree of the 16S rDNA affirmed the findings of the cluster analysis derived from the geometric morphometric method in differentiating A. m. carnica and A. m. ligustica from Iranian honeybees. The cluster analysis grouped reference subspecies of A. m. meda with Iranian honeybees. Moreover, the Discriminant Function Analyses (DFA) differentiated Iranian honeybees from A. m. ligustica and A. m. carnica.     

<Emphasis Type="Italic">Notohymena saprai</Emphasis> sp. nov,a new oxytrichid ciliate (Protozoa,Ciliophora) from the Valley of Flowers,a Himalayan bioreserve region; description and morphogenesis of the new species

A new oxytrichid ciliate Notohymena saprai sp. nov was isolated from the Valley of Flowers, an isolated bioreserve in the upper Himalayas. The ciliate was found in the soil samples collected from the peripheral areas of the flowering region of the valley which is covered with permafrost for nearly eight months in a year. Cells were excysted from the soil samples by the non-flooded petridish method. Species identification was performed by observations on live and silver-impregnated cells. Notohymena saprai sp. nov is highly flexible, measures 152 × 49 μm and shows abundant presence of dark green sub-pellicular granules. The species is distinct by virtue of its new combination of morphometric and developmental characters. Prominent distinguishing features of the new species are its relative large size and presence of four macronuclei (other species of this genus have two macronuclei). The study also reports morphogenetic peculiarities which separate it from the other known species of the genus.     

Shell form,growth and life span of <Emphasis Type="Italic">Astarte arctica</Emphasis> and <Emphasis Type="Italic">A. borealis</Emphasis> (Mollusca: Bivalvia) from the subtidal zone of northeastern Sakhalin

This study investigates changes in body proportions during ontogenesis of the bivalves Astarte arctica and A. borealis from the subtidal zone of northeastern Sakhalin. Marked differences in the shell form of bivalves were found. The shell of A. arctica is convex and compact, shell length and height are comparable, and shell width is more than 50% of shell height. A. borealis has a slightly elongate and flattened shell, its width is less than 50% of its height. Shell proportions can provide a reliable criterion for differentiating the species. Mollusks grow at nearly the same rate but attain different maximum sizes. Linear growth is described by Bertalanffy’s equation: L_t = 48.2[1 ? e ^{?0.4850(t ? 0.4396)}] for A. arctica and L_t = 53.1[1 ? e^{?0.4106(t ? 0.4253)}] for A. borealis. In northeastern Sakhalin, the life span of A. arctica is 7 years and of A. borealis, 8 years. By life span, the two bivalve species from Sakhalin slightly differ from their counterparts in other regions, particularly the arctic seas.     

A fish bradykinin (Arg0, Trp5, Leu8-bradykinin) from the defensive skin secretion of the European edible frog, Pelophylax kl. esculentus: structural characterization; molecular cloning of skin kininogen cDNA and pharmacological effects on mammalian smooth muscle

Extensive studies on bradykinin-related peptides (BRPs) generated from plasma kininogens in representative species of various vertebrate taxa, have confirmed that many amphibian skin BRPs reflect those present in putative vertebrate predators. For example, the (Val¹, Thr⁶)-bradykinin, present in the defensive skin secretions of many ranids and phyllomedusines, can be generated from plasma kininogens in colubrid snakes—common predators of these frogs. Here, we report the presence of (Arg⁰, Trp⁵, Leu⁸)-bradykinin in the skin secretion of the European edible frog, Pelophylax kl. esculentus, and have found it to be encoded in single copy by a kininogen with an open-reading frame of 68 amino acid residues. This peptide is the archetypal bony fish bradykinin that has been generated from plasma kininogens of the bowfin (Amia calva), the long-nosed gar (Lepisosteus oseus) and the rainbow trout (Onchorhynchus mykiss). More recently, this peptide has been shown to be encoded within cloned kininogens of the Atlantic cod (Gadus morhua) spotted wolf-fish (Anarichas minor), zebrafish (Danio rerio), pufferfish (Tetraodon nigroviridis) and Northern pike (Esox lucius). The latter species is regarded as a major predator of P. kl. esculentus. Synthetic (Arg⁰, Trp⁵, Leu⁸)-bradykinin was previously reported as having multiphasic effects on arterial blood pressure in conscious trout and here we have demonstrated that it can antagonize the relaxation in rat arterial smooth muscle induced by canonical mammalian bradykinin. The discovery of (Arg⁰, Trp⁵, Leu⁸)-bradykinin in the defensive skin secretion of this amphibian completes the spectrum of vertebrate taxon-specific BRPs identified from this source.