Osservazioni sul comportamento sessuale del Populus tremula L. in Italia

Abstract

OBSERVATIONS ON SEXUAL BEHAVIOUR OF POPULUS TREMULA L. IN ITALY. — A research has been carried on sex distribution of Populus tremula in Italy. On 101 observed populations the sexual ratio resulted of 2:1 in favour of male sex. The analysis of results referred to the two geographycal sectors of the peninsula, North and MiddleSouth, is however showing some discordant data in the sexual composition of several populations. In North-Italy the ratio results of 2,5:1 in favour of male sex, in MiddleSouth 1:1.

These discordant results would show that male sex can be adapted whether in continental or in mountain climate.

The Author deems that the geographycal position of populations and corresponding climatic characteristics can be responsible for the sexual selection, so that the several deviations wich are found in natural populations of P. tremula can get an explanation in an possible correlation between habitat and sex.

The Author dwells particulary upon population discovered at Campiglione, near Pozzuoli (Naples). Stamens, varying in number from 2 to 4, were observed on almost all the pistillate flowers of every single catkin of these individuals and especially from the base to a little over halfway up the catkin.

The high proportion of bisexual catkins found on every individual examined leads to the conclusion that P. tremula is « polygamo-dioecious » in character, that is, it produces bisexual and unisexual character in the case of P. tremuloides, where, however, in the majority of the bisexual individuals, the percentage of hermaphrodite flowers on one catkin was very small (1–2%).

These cases of bisexuality lead one to thing that dioecism is an acquired character in the genus Populus. This condition (wich, at least in the case of P. tremula, is perhaps to be connected with the poor fertility of the species) could in time have lead to the present geographycal distribution in colonies of isolated and sexually anbalanced individuals.

These cold have survived to our times due to their aptitude vegetative propagation by means of suckers, giving rise to scattered clumps of unisexual individuals of the same clone. The finding of these bisexual individuals is of considerable importance for applied genetics, and could initiate new researches in Italy to obtain genotypic and polyploid descendants.     

Fertility and sexual structure in a polygamous willow population

This note reports on an extraordinary polygamous population of Salix acmophylla from Nahal Dishon, Israel. Remarkably, all individuals in this population are bisexuals, that is, they all contain typically female catkins (with some or without any male florets), typically male catkins (with some or without any female florets) and mixed catkins. The proportions of these three catkin types in populations are 36.3%, 46.8% and 16.9% respectively. The fertility of these willows was found to be poor: no mature seeds were found at all and mean pollen stainability was low as 15.6%. The possible reasons for this semi-sterility are discussed.     

胡杨、灰叶胡杨花空间分布及数量特征研究

研究了不同居群的胡杨、灰叶胡杨花空间分布及其数量特征。结果表明,无论是胡杨还是灰叶胡杨,其雄树的树高、最低花位、集花区下限、集花区上限、最高花位皆低于雌树,并且雌株与雄株的花序分布范围亦有着较大的重叠区域。在树体上,雄花序主要分布在树冠的中部,上部次之,下部最少;雌花序主要分布在树冠的上部,中部次之,下部最少。胡杨的单株花序量、花朵花药数、花药花粉量和花序花粉量均小于灰叶胡杨,而花序花朵数胡杨雄树的小于灰叶胡杨,雌树的大于灰叶胡杨。统计分析表明,不同居群胡杨的单株花序量、花序花朵数与花药花粉量是相对稳定的,而灰叶胡杨仅雄树的单株花序量是稳定的。     

华木莲居群遗传结构与保护单元

华木莲(Sinomanglietia glauca)仅分布于江西宜春和湖南永顺, 是我国一级重点保护植物。前人采用RAPD、ISSR以及叶绿体SSCP(single-stranded conformation polymorphism)标记对华木莲进行了居群遗传学研究, 但未包括后发现的湖南居群或未检出居群内遗传变异。为了全面检测华木莲遗传多样性及其空间分布格局, 并据此确定保护单元, 本研究采用细胞核微卫星标记对华木莲所有4个居群共77个个体进行了居群遗传学分析。结果表明, 华木莲具有较低的遗传多样性(平均等位基因数A = 2.604, 平均期望杂合度H_E = 0.423)和较高的遗传分化(F_ST = 0.425)。STRUCTURE和主成分分析(Principal Coordinated Analysis, PCA)将4个居群首先分为江西、湖南两组, 江西的2个居群实际上是同一个自然繁育居群, 而湖南的2个居群则为2个分化明显的自然繁育居群。研究还发现湖南居群存在明显的杂合子过剩现象, 可能是小居群内随机因素造成的。研究结果表明华木莲可能在近期历史上遭受过强烈的瓶颈效应, 导致种群缩小、遗传多样性丧失和居群分化加剧, 需要加强对其进化潜力的保护。在制定保护措施时, 需要考虑其较高的遗传分化水平, 根据遗传结构可以将其划分为3个保护单元, 即湖南居群和江西居群分别为2个进化显著单元, 湖南居群进一步划分为2个管理单元(分别为朗溪乡云盘村和小溪乡鲁家村居群)。     

西藏极小种群野生植物密叶红豆杉种群的性比及雌雄空间格局

雌雄异株植物种群具有性比和雌雄个体空间分布格局, 这对个体成功繁殖、种群生存潜力、天然更新能力和遗传多样性的维持都是重要的, 对于珍稀濒危雌雄异株植物种群尤其如此。密叶红豆杉(Taxus fuana)为国家I级重点保护植物, 是首批列入《全国极小种群野生植物拯救保护工程规划》的120种极小种群野生植物之一, 具有重要的生态和经济价值。但目前关于密叶红豆杉种群生态学方面的研究, 尤其是性比结构与空间分布格局在国内外鲜有报道。本文对西藏吉隆地区的6个天然密叶红豆杉种群(吉普、多甫、朗久、吉隆、开热和唐蕃)进行了实地调查, 研究其性比结构及其空间分布格局。结果表明, 调查的6个种群中总计雄株1,651株, 雌株1,231株, 仅吉普(雄/雌 = 1.89)与吉隆(雄/雌 = 1.39)两个种群有显著的性别偏倚现象且显著偏雄性(P < 0.001)。6个种群雌雄植株间的空间相关性不强, 整体趋于相互独立。不同径级间, 吉隆和开热种群的性比格局相似, 均在小径级上性比显著偏雄性, 而吉普种群则在中等径级上显著偏雄性。综上, 不同密叶红豆杉种群的大小、性比、雌雄个体的大小级结构以及空间分布格局等均表现出不同。因此, 需要结合各个种群本身的发展动态、受干扰的类型以及各区域环境因子的差异进行有针对性的保护。     

中国东北柳属花粉形态及其系统学研究

本研究对中国东北地区产柳属17个组的29种, 6变种, 1变型的花粉进行了光学显微镜和扫描电子显微镜观察。结果表明, 同一种的花粉粒形态相对稳定, 花粉粒的萌发孔类型, 表面网状纹饰类型及纹饰的亚显微形态, 及外壁厚度等特征与组的关系较密切, 而在组内各种间趋于一致;种间自然杂交种的花粉粒形态特征, 表现其亲本的中间类型。聚类分析结果表明, 五蕊柳与大白柳组进化关系密切。     

Discovery of Bisexual Flowers in Pterocarya Stenoptera C. DC.

This paper reports the bisexual structure of the flowers of Pterocarya stenoptera. The bisexual flowers are borne at the end of a leafy shoot of the current year in many-flowered terminal pendulous catkins. They have the same structure as the general female ones. Each flower grows in the axil of a bract, with a pair of bracteoles and four small perianths. Each flower has two or three carpels in the centre of the flower, and upon them there are two or three styles with stigmas on the inner face. They differ from the general female ones in that each of them contains 4-6 stamens, forming a single whorl. The stamens alternates with, or is opposite to, the perianth elements. Sometimes they contain 8 (-10) stamens, forming two whorls, with 6 in the outer whorl and 2 (-4) in the inner whorl, and in this case the pistil in the bisexual flower of terminal catkins often becomes a rudiment. It is interesting that we have also found bisexual flowers in another tree, which are borne in lateral male catkins. They have the same structure as general male ones, and the pistils are often represented by a rudiment. Manning (1940) points out that some female flowers of Pterocarya stenoptera and P. fraxinifolia occasionally have stamens ( ? ) opposite the sepals. In P. stenoptera we have found that both the stamens and the stigmas of bisexual flowers are functional. They are capable of producing functional fruits. This is the same case as in Myrica Gale described by Davey and Gibson (1917). Rendle (1952) points out that in the male flowers of Platycarya the pistils often appeared as a rudiment. He considers, however, the male flowers derived from the bisexual flowers with an indefinite number of stamens. The rudimentary pistils of lateral male catkins in P. stenoptera we found are just the same as the ones found in Platycarya by Rendle. The discovery of the bisexual flowers in P. stenoptera may prove that the unisexual flowers of the present-day Juglandaceae are derived from ancestors with bisexual flowers.This tends to support the hypothesis that Cycadicae is the possible ancestor of the angiosperms.     

Fertility of exceptional bisexual individuals in four dioecious plant species

Exceptional, very rare, bisexual (hermaphroditic or monoecious) individuals have been detected in strictly dioecious populations of Rhamnus alaternus, R. palaestinus, Bryonia syriaca and Populus euphratica (a single individual in each species). While ordinary male plants in each species exhibited fully normal pollen, and female individuals set a considerable amount of fruit, the exceptional bisexual plants showed a reduction in male or female fertility, or both. This inability of the rare bisexual individuals to fully invest in the two genders suggests that trade-offs between male and female functions possibly play a major role in the breeding systems of these dioecious species, and probably implicates resource allocation (among other factors) as a selective force in the evolution of dioecy. Received: 5 April 1999 / Revision accepted: 30 June 1999     

Biodiversity of Saccharomyces cerevisiae isolated from a survey of pito production sites in various parts of Ghana

Biodiversity among Saccharomyces cerevisiae predominating the spontaneous fermentation of Dagarti pito in Ghana was assessed. Two hundred and forty-nine isolates obtained from samples of dried yeast taken from commercial pito production sites in eight geographical regions of Ghana were characterized phenotypically by colony and cell morphology as well as carbohydrate assimilation profiling. Yeast populations ranged between 10⁶ and 10⁸ cfug⁻¹. Ninety-nine percent of the isolates (247) investigated showed macro-and micro morphological characteristics typical of S. cerevisiae. Of these, 72% (179) had assimilation profiles similar to S. cerevisiae while 28% (68) had assimilation profiles atypical of S. cerevisiae or any other member of the Saccharomyces sensu stricto complex. Amplification of the region spanning the two intergenic transcribed spacers (ITS) and the 5.8S ribosomal gene (ITS1-5.8S rDNA-ITS2), followed by restriction analysis, as well as determination of chromosome length polymorphism by pulsed field gel electrophoresis (PFGE) of 25 representative isolates strongly indicated that all belonged to S. cerevisiae, notwithstanding the phenotypic differences. Sequencing of the mitochondrial cytochrome-c oxidase II gene (COX 2) and the actin-encoding gene (ACT1) of four isolates, confirmed their close relatedness to S. cerevisiae, particularly to the type strain CBS1171 (98.7%), as well as other members of the Saccharomyces sensu stricto complex. Twenty isolates selected from eight geographical regions of Ghana and investigated for their technological properties, showed different patterns of growth and flocculation but otherwise similar technological characteristica. Most of the isolates produced pito having sensory attributes, which compared favourably with commercially produced pito.     

Seasonal changes in water and fat content and fatty acid composition of the catkin buds of Alaska willow (Salix alaxensis)

Summary Catkin buds of Salix alaxensis from interior Alaska were analyzed for water and lipid content and fatty acid composition throughout the year. Water content was significantly correlated with environmental temperature, but lipid content was not. Linoleic acid (18:2) and arachidic acid (20:0) were predominant in the lipids of whole catkins.Of the 27 different fatty acids found in all weekly samples, 11 showed pronounced seasonal variation, most of which occurred during catkin development and flowering in spring. During winter, only the amount of linoleic acid in the catkins was significantly negatively correlated with change in ambient temperature.Histological and chemical analyses of the catkin florets and catkin scales revealed that 99% of the linoleic acid was located in the florets primarily in the form of triglycerides while 94% of the arachidic acid was located in the catkin scale primarily as wax esters. While the linoleic acid in the triglycerides of the meristematic florets probably provides an energy source for the developing catkins, the large amounts of arachidic acid located in the catkin scales probably serves to prevent dessication of the catkins during the long, cold and dry arctic winters.     

Effects of pinealectomy, melatonin injections and melatonin antibody production on the mean duration of individual hibernation bouts in Spermophilus tridecemlineatus

1. 1.|Pinealectomy did not significantly alter the length of the mean durations of individual hibernation bouts in adult Spermophilus tridecemlineatus.

2. 2.|Similarly, no statistically-significant differences in mean durations of individual hibernation bouts between pinealectomized and sham-pinealectomized group squirrels were observed for young-of-the year S. tridecemlineatus

3. 3.|Some apparent differences of pinealectomy are suggested as they relate to age, stage of hibernation cycle and time of year during which pinealectomies are performed.

4. 4.|Daily s.c. injections of 50 μg of melatonin late in the subjective photophase induced no statistically-significant differences in mean durations of individual hibernation bouts between either adult, female pinealectomized or intact S. tridecemlineatus and their respective controls.

5. 5.|Adult, female S. tridecemlineautus with reduced titres of endogenous melatonin displayed on statistically-significant difference in the mean duration of initial hibernation bouts compared with controls.

6. 6.|It is possible that melatonin per se or that pinealectomy or melatonin titre alterations are generally failing to induce any significant changes in the torpor/arousal cycles of seasonal hibernators; or that a parameter other than the duration of torpor/arousal cycles is being modulated by the pineal complex.

黄河三角洲盐碱地不同植被模式的土壤改良效应

黄河三角洲是我国滨海盐碱地的重要分布区,种植植被是盐碱地绿色改良的主要生态修复措施。为探讨滨海盐碱地不同植被模式的土壤改良效应,探索适宜植被模式,选取黄河三角洲盐碱地竹柳+NyPa草、旱柳+NyPa草、柽柳+紫花苜蓿、白蜡+柽柳+紫花苜蓿4种林草措施为研究对象,以纯竹柳为对照,测定土壤水分物理参数、盐碱含量、土壤养分及微生物数量等20个指标,并利用主成分分析、聚类分析和模糊数学隶属函数等统计方法评价了不同植被模式的土壤改良效应。结果表明: 林草复合模式可显著改善滨海盐碱地的土壤理化性能,增加土壤孔隙度和贮水量,降低土壤密度,提高土壤有机质、速效养分含量和土壤微生物数量。其中,白蜡+柽柳+紫花苜蓿的乔灌草混交模式在压碱抑盐、增加土壤养分和微生物数量的效果最好,而旱柳+NyPa草的乔草混交模式改良土壤水分物理性能的效果最好。不同植被模式对黄河三角洲滨海盐碱地的综合改良效应表现为白蜡+柽柳+紫花苜蓿>旱柳+NyPa草>竹柳+NyPa草>柽柳+紫花苜蓿。     

天目山不同海拔檫木群体遗传多样性和遗传结构

采用13对SSR引物,运用Bioptic Qsep100全自动核酸分析系统,分析了天目山5个海拔檫木群体的遗传多样性和遗传结构及其在不同海拔下的变化模式.结果表明: 天目山檫木群体具有较高的遗传多样性水平,其中期望杂合度和观察杂合度分别为0.84和0.61.根据Shannon指数,天目山檫木中海拔(500～800 m)群体的遗传多样性水平大于低海拔(200 m)和高海拔(1100～1400 m)群体的遗传多样性水平.由基因分化系数和AMOVA分析可知,檫木种群的遗传变异主要存在于群体内.STRUCTURE分析和UPGMA聚类分析表明,中、低海拔被划为一个群体,而高海拔被划为另一个群体.低海拔和中海拔檫木群体遗传距离的差异表明,人为干扰对物种多样性具有负面效应,而自然保护区对物种多样性的保护起到了积极作用.     

高寒退化草地狼毒种群不同海拔花大小-数量的权衡关系

权衡关系是植物生活史对策理论的基础, 花大小-数量的权衡关系对理解花的生物量分配具有重要的意义。该文利用实验生态学方法, 研究了祁连山北坡高寒退化草地4个不同海拔狼毒(Stellera chamaejasme)种群花大小与花数量间的关系。结果表明: 随着海拔升高, 草地群落的高度、密度和地上生物量均呈先升高后降低的倒U型分布, 狼毒花大小呈逐渐增大的趋势, 而花数量呈相反的变化趋势; 不同海拔样地狼毒花大小与花数量间的相关性存在差异, 海拔2700、2900和3000 m样地狼毒花大小和花数量之间均存在极显著的负相关关系(p < 0.01), 海拔2800 m样地二者之间存在显著的负相关关系(p < 0.05), 狼毒植株分配给花大小与花数量的资源间存在着“此消彼长”的权衡关系; 海拔2800 m样地是狼毒植株花大小与花数量权衡关系由低海拔的花数量多而单花生物量低向高海拔的花数量少而单花生物量高转变的区域。狼毒植株通过合理权衡花数量和花大小的资源配置, 以补偿在海拔梯度上不利因素对种群繁衍带来的影响, 从而实现种群的繁殖成功, 反映了毒杂草对异质性生境的表型可塑性机制。     

Assessing Costs of Reproduction in Mountain Birch: The Importance of Considering the Modular Level

We studied the effects of production of male catkins on growthand the subsequent year's male catkin production in mountainbirch, Betula pubescens subsp. czerepanovii at both the shootand branch level. (Shoot is defined here as the product of asingle growing season while branch refers to a structure consistingof several shoots.) Like heterophyllous trees in general, mountainbirch canopy expansion takes place via the production of longshoots. We found phenotypic trade-offs between long shoot growthand male reproduction at the shoot level in the year of catkinproduction. Generative parental long shoots (long shoots withmale catkins) were significantly shorter than the vegetativeones (long shoots without a male catkin). In contrast, we foundno effects of male reproduction on the subsequent year's malecatkin production at the shoot level. Although the mean lengthof secondary long shoots (long shoots growing from the lateralbuds of parental long shoots) did not differ between vegetativeand generative parental long shoots, there was considerablebetween-individual variation in the response of individual trees.In addition, production of male catkins diminishes canopy expansionin mountain birch because the number of secondary long shootsproduced by generative parental long shoots was smaller thanthat of vegetative parental long shoots. At the branch level,the association between total long shoot growth and male catkinproduction was positive, i.e. no trade-off was found. This maybe because the strong sink strength (the ability of a branchto import assimilates from elsewhere in the tree) of branchesbearing reproductive long shoots masks possible trade-offs.We emphasize the importance of considering several levels ofthe modular hierarchy when analysing costs of reproduction inmodular organisms. Copyright 2000 Annals of Botany Company Hierarchical structure, modularity, mountain birch, short and long shoots, trade-off, Betula pubescens subsp.czerepanovii (Orlova) Hämet-Ahti     

荒漠北沙柳根系丛枝菌根真菌和黑隔内生真菌定殖状况

为利用土壤共生真菌资源促进荒漠植被恢复和生态重建, 分别于2013年6月、8月和10月, 从内蒙古元上都地区采集北沙柳(Salix psammophila)根围0-10、10-20、20-30、30-40和40-50 cm共5个土层的土壤样品, 系统研究了丛枝菌根真菌(AMF)和黑隔内生真菌(DSE)的时空分布及其与土壤因子的相关性。结果表明: AMF和DSE的平均定殖率分别为77%和84%, 说明北沙柳根系能与这两类真菌形成良好的共生关系。AMF和DSE的分布和定殖具有明显的时空异质性, 并与土壤因子密切相关。AMF和DSE的平均定殖率均表现为10月> 8月> 6月。土壤深度对AMF和DSE的定殖率有显著影响, AMF和DSE定殖率的最大值分别在0-20 cm和0-10 cm土层。双因子方差分析表明, 月份和土层对AMF和DSE的定殖率以及土壤因子具有显著的交互效应。主成分分析表明, 土壤湿度、pH值、碱性磷酸酶、易提取球囊霉素是内蒙古荒漠环境中AMF和DSE定殖的主要影响因子。     

松树蜂的产卵行为

【目的】研究松树蜂Sirex noctilio的产卵行为,明确其产卵能力,为评估其繁殖潜力和危害能力提供基础数据。【方法】于黑龙江省大庆市杜尔伯特蒙古族自治县新店林场采集被松树蜂危害的寄主樟子松Pinus sylvestris var.mongolica木段上获得虫源。在室内条件下观察和分析松树蜂产卵的行为过程及规律。解剖松树蜂在樟子松木段上的产卵孔,并观察其结构特征。【结果】松树蜂羽化时即性成熟,能够马上进行交配和产卵。松树蜂雌成虫一次完整的产卵过程主要分为4个动作:树皮钻孔、木质部钻刺、产卵(注入有毒黏液和共生真菌Amylosereum areolatum)和产卵器拔出。产卵时间在360～540 s之间的产卵频数最多,占产卵总频数的41.40%;产卵过程中木质部钻刺用时最长,至少占整个产卵过程用时的90%。松树蜂雌成虫在一个产卵孔处会进行1～4次产卵,产卵时间和产卵次数呈显著正相关,当产卵时间t<360 s时,进行了1次产卵;当360 s≤t<540 s时,进行了2次产卵;当540 s≤t<780 s时,进行了3次产卵;当t≥780 s时,进行了4次或更多次产卵。松树蜂在一个产卵孔处进行1, 2, 3和4次产卵的比例分别为21.66%, 41.40%, 27.39%和9.55%。【结论】松树蜂雌成虫在一个产卵孔处的产卵时间和产卵次数呈正相关。利用产卵时间和产卵次数的关系,在只调查产卵时间的情况下,可以推断产卵次数。松树蜂在一个产卵孔处产卵的次数多,对寄主樟子松危害大。     

中国西藏土壤中节格孢属真菌的三个新种

从中国西藏土壤中分离到3种节格孢属Scytalidium真菌,据形态学特征和分子系统学分析,他们不属于该属中任何已知种,遂在本文中作为新种加以描述和发表,它们是：具有多纵隔膜的中国节格孢S. chinense、能产红色色素的西藏节格孢S. tibetense和孢子与菌丝均具瘤突的具瘤节格孢S. tuberculatum。新种的模式标本（干制培养物）分别保藏在山东农业大学植物病理学标本室（HSAUP）和中国科学院菌物标本馆（HMAS）。     

Plant nutrient dynamics and stoichiometric homeostasis of invasive species Spartina alterniflora and native Cyperus malaccensis var. brevifolius in the Minjiang River estuarine wetlands

Aims Stoichiometric homeostasis is an important mechanism in maintaining ecosystem structure, function, and stability. The invasion of exotic species, Spartina alterniflora, has largely threatened the structure and function of native ecosystems in the Minjiang River estuarine wetland. However, how S. alterniflora invasion affect plant stoichiometric homeostasis is largely unknown. This could enhance our understanding on wetland ecosystem stability and expand the applications of ecological stoichiometry theory.
Methods Nitrogen (N) and phosphorus (P) contents of plant organs and soils in the S. alterniflora, Cyperus malaccensis var. brevifolius, and S. alterniflora-C. malaccensis var. brevifolius mixture were measured, and the homeostatic index (H) was calculated according to the stoichiometric homeostasis theory.
Important findings Our results showed that the invasion of S. alterniflora significantly increased soil N:P ratio (p < 0.05), but did not affect soil N or P contents. The N and P contents of leaf and stem were the highest for S. alterniflora, and those of the stem were the highest for C. malaccensis var. brevifolius. At the ecosystem level, the average of homeostatic index (H) of N (H_N, 25.31) was larger than those of P (H_P, 10.33) and N:P (H_N:P, 2.50). At the organ level, root H_N was significantly larger than stem H_N (p < 0.05) and sheath H_N:P was greater than root H_N:P (p < 0.05), while there was no significant difference for H_P among root, stem, leaf, and sheath (p > 0.05). As for species, root H_N of S. alterniflora was significantly larger than that of C. malaccensis var. brevifolius in the mixture community (p < 0.05). In the monoculture, stem H_N:P of S. alterniflora was significantly higher than that of C. malaccensis var. brevifolius (p < 0.05). Furthermore, root H_N, leaf H_N and sheath H_N of S. alterniflora in the mixed community was significantly larger than that of S. alterniflora in the monoculture (p < 0.05), suggesting that S. alterniflora invasions increased their stoichiometric homeostasis. Meanwhile, the stoichiometric homeostasis of invasive and native plants were influenced by multiple factors, such as nutrients, organs, vegetation, and invasion. However, larger homeostasis was found in S. alterniflora than in C. malaccensis var. brevifolius in some particular organs either in mixture or monoculture communities. Therefore, the successful invasion of S. alterniflora may result from higher homeostatic index than the native species, C. malaccensis var. brevifolius.     

Identification of novel suppressors for Mog1 implies its involvement in RNA metabolism, lipid metabolism and signal transduction

Mog1 is conserved from yeast to mammal, but its function is obscure. We isolated yeast genes that rescued a temperature-sensitive death of S. cerevisiae Scmog1Δ, and of S. pombe Spmog1^ts. Scmog1Δ was rescued by Opi3p, a phospholipid N-methyltransferase, in addition to S. cerevisiae Ran-homologue Gsp1p, and a RanGDP binding protein Ntf2p. On the other hand, Spmog1^ts was rescued by Cid13 that is a poly (A) polymerase specific for suc22⁺ mRNA encoding a subunit of ribonucleotide reductase, Ssp1 that is a protein kinase involved in stress response pathway, and Crp79 that is required for mRNA export, in addition to Spi1, S. pombe Ran-homologue, and Nxt2, S. pombe homologue of Ntf2p. Consistent with the identification of those suppressors, lack of ScMog1p dislocates Opi3p from the nuclear membrane and all of Spmog1^ts showed the nuclear accumulation of mRNA. Furthermore, SpMog1 was co-precipitated with Nxt2 and Cid13.