Restriction of sexual reproduction in the moss Racomitrium lanuginosum along an elevational gradient

1. Terrestrial plant populations located at the margins of species’ distributions often display reduced sexual reproduction and an increased reliance on asexual reproduction. One hypothesis to explain this phenomenon is that the decline is associated with environmental effects on the energetic costs to produce reproductive organs.
2. In order to clarify the changing processes of sexual reproduction along an elevational gradient, we investigated the sexual reproductive parameters, such as the number of sporophytes and gametangia, in Racomitrium lanuginosum, a dioicous moss found on Mt. Fuji.
3. Matured sporophytes were present only below 3,000 m, and the number of sporophytes per shoot tended to be lower at higher elevation habitats. The numbers of male inflorescences per shoot and antheridia per inflorescence and shoot significantly decreased with increasing elevation. In contrast, the numbers of female inflorescences per shoot and archegonia per inflorescence and shoot varied little across elevations.
4. Synthesis. Our results suggest that the reasons for this limitation are assumed to be limitations in sporophyte development that result in abortion, and the spatial segregation between males and females. Possible reasons for the abortion of sporophytes are the inhibitory effects of low air temperature, a shortened growth period, and winter environmental conditions at higher elevations. Remarkable differences between male and female on various reproductive parameters found in this study are thought to affect the mode of sexual reproduction under the harsh environment. These differences between males and females may be caused by differences in the costs of production and development of gametangia, sensitivity to environmental stressors, and phenological patterns.

     

Review of the West Indian genus Monotalla Bechyné (Coleoptera,Chrysomelidae, Galerucinae,Alticini) with description of five new species

The West Indian genus Monotalla Bechyné is reviewed, redescribed and illustrated. Five new species are added: Monotalla dominica sp. n. (Dominica); Monotalla lecticofolia sp. n. (St. Lucia); Monotalla maierae sp. n. (St. Lucia); Monotalla obrienorum sp. n. (Grenada); and Monotalla viridis sp. n. (St. Lucia). A key to Monotalla species is provided.     

Leaf Surface Microflora May Significantly Affect Studies on Foliar Uptake of Chemicals

Uptake and desorption kinetics of methylglucose and pentachlorophenol (PCP) by needles of Picea abies (L.) Karst. were studied. Uptake of methylglucose was very rapid, equilibrium was obtained within 2 h and the amounts of methylglucose associated with the needles could be completely desorbed within 8 h. In contrast, PCP uptake was steady for several hours and the amounts of PCP taken up could only partially be desorbed again. Needles treated with NaN₃ prior to uptake measurements, showed no methylglucose uptake at all, whereas PCP uptake was not affected. Thus it is concluded that the hydrophilic methylglucose was taken up solely by epiphytic microorganisms, whereas the lipophilic PCP was taken up into the needle interior in significant amounts. Consequences of these results on studies of foliar uptake of chemicals are pointed out.     

贵州普定喀斯特石生藓类生态分布与环境因子的相关分析

苔藓植物与环境的相关性一直是苔藓生态学的研究热点,研究喀斯特石生苔藓分布与环境的关系,为深入石生苔藓植物生态学研究提供理论依据。选择贵州普定石漠化区域石生环境中的5个大样方25个小样方125个采集点进行调查,采集苔藓植物并测定收集了相关的环境因子数据。结果发现:(1)样方共采集到标本267份,经鉴定有石生藓类54种。其中,丛藓科、灰藓科为优势科(属数≥3),曲柄藓属、扭口藓属、真藓属等为优势属(种数≥3),丛藓、细牛毛藓、美灰藓、绿羽藓为优势种(次数≥3)。(2)运用典范对应分析(CCA)分析了影响该地区石生藓类分布的主要环境因素,发现石生藓类分布与坡度呈显著的负相关;与其它环境因子相关的重要性依次为岩面倾角、海拔、土壤中全钾含量、土壤厚度和pH。因此,研究环境因子对石生藓类分布的关系可以为石漠化综合治理以及石面绿化植物的筛选提供参考。     

New,interesting and rare species of non-lichenized fungi recorded around Kindrogan,Perthshire in 1991

Summary

Notes are given of species of special interest, including several which are newly observed or rare in Britain, recorded in a survey of fungi around Kindrogan, Perthshire in September 1991.     

New Indole Diketopiperazine Alkaloids from Soft Coral-Associated Epiphytic Fungus Aspergillus versicolor CGF 9-1-2

Two new indole diketopiperazine alkaloids (IDAs), (+)19-epi-sclerotiamide ( 1 ) and (−)19-epi-sclerotiamide ( 2 ), along with 13 known analogs ( 3 – 15 ), were isolated from a soft coral-associated epiphytic fungus Aspergillus versicolor CGF 9-1-2. The structures of two new compounds were established based on the combination of HR-ESI-MS, 1D and 2D NMR spectroscopy, optical rotation measurements and quantum chemical ¹³C-NMR, the absolute configurations were determined by experimental and electronic circular dichroism (ECD) calculations. The results of molecular docking showed that all the compounds had a good binding with TDP1, TDP2, TOP1, TOP2, Ache, NLRP3, EGFR, EGFR L858R, EGFR T790M and EGFR T790/L858. Biological evaluation of compounds 3 , 6 , 8 , 11 showed that 3 exerted a strong inhibitory effect on TDP2 with a rate of 81.72 %.     

Cupressaceae pollen: new data about diffusion,record and preservation

Abstract

Cupressaceae is one of the most widespread families in the Mediterranean region, widely used as ornamental trees both in cities and extra urban areas. The family is also known to produce a considerable amount of pollen grains. Nevertheless, Cupressaceae pollen is generally scarce in sediments and it is attested to be one of the most underrepresented pollen in ancient spectra. Cupressaceae pollen diffusion was detected by means of two sampling methods: moss cushions, which are able to accumulate pollen grains for several successive years, and volumetric sampler, which records the airborne pollen day by day. The study was conducted in the city of Florence (Italy), repeating moss samplings at the same sites for three times. The comparison between the two sampling methods revealed the low preservation of this pollen type and suggested that even low quantities of this pollen may indicate the local presence of the source plants. In order to test the contribution of the local pollen sources to the background of the airborne pollen, the pollen content of moss cushions was also related to the number of Cupressaceae plants surroundings each sampling site. The results indicate a noticeable influence of the plants growing in a short-range distance.     

Esterified long-chain hydroxy acids in green and senescent parts of the peat moss Sphagnum fuscum

The bifunctional long-chain acids in extracts and alkaline hydrolysates of extractive-free tissues from the green and senescent parts of Sphagnum fuscum were investigated by GC and GC/MS. A series of C₁₄– C₂₆hydroxy acids was liberated by alkaline hydrolysis of senescent tissue demonstrating the presence of insoluble polymeric lipid esters in the moss. In the corresponding hydrolysates of the topmost green parts of the shoot the amounts of these acids were significantly smaller. It is suggested that the presence of such polymeric esters in S. fuscum contributes to the cell-wall resistance of this peat-forming moss.     

Cytokinin activation and redistribution of plasma-membrane ion channels in Funaria

I have investigated changes in electrical current across the plasma membrane that occur during cytokinin-induced bud formation in Funaria hygrometrica Hedw., using a non-intrusive vibrating microelectrode. Before cytokinin treatment the target caulonema cells have maximal inward current at the nuclear region. After cytokinin treatment inward current increases twofold along the length of the cell. Within minutes, however, current decreases at both the nuclear zone and the proximal end while increasing at the distal end of target cells, preceding and predicting the presumptive division site. Inward current at the distal end falls to resting levels after establishment of a bulging growth zone, and remains low around developing buds. This current is blocked by gadolinium nitrate, a Ca²⁺-uptake inhibitor, indicating a Ca²⁺ component of the current. The polarity of the target cells can be disrupted by microfilament inhibitors and cytokinin-induced buds form over the nucleus, halfway along the length of the cell. I suggest that cytokinin activates plasma-membrane ion channels which are subsequently redistributed to the distal ends of target cells by a microfilament-dependent process. Cytokinin-induced concentration of ion channels over presumptive bud sites may be envisioned to exert spatial control of cytoplasmic ion concentrations and stimulate bud formation by establishing a new growth zone, directing nuclear migration, and stimulating cell division.Abbreviations BA 6-benzyladenine - [Ca²⁺]_i intracellular calcium-ion concentration