VOLVOX POCOCKIAE,A NEW SPECIES WITH DWARF MALES1

Volvox pocockiae is described as the second species in the section Janetosphaera. The somatic protoplasts are connected by cytoplasmic strands approximately the same diameter as flagella, and the construction of the spheroid is identical to that of V. aureus. Asexual reproduction by the division of gonidia differs from that in V. aureus in the enlargement of the gonidium prior to its division to form the embryo. Sexual reproduction is very similar to that in V. spermatosphaera, a species in the section Merrillosphaera without cytoplasmic connections. Dwarf males are formed in the posterior end of the parental spheroid, and, as in V. spermatosphaera, the dwarf males are composed exclusively of androgonidia with no sterile somatic cells. Females are facultatively asexual spheroids, the gonidia of which function as eggs. The single biflagellate zoospore produced by the germinating zygote undergoes cleavage to form a germling spheroid. The differentiation of gonidia in the asexual embryo and in the germling spheroid is evident only after inversion and enlargement of the spheroid have begun.     

EVOLUTION OF SEX DETERMINATION SYSTEMS WITH HETEROGAMETIC MALES AND FEMALES IN SILENE

The plant genus Silene has become a model for evolutionary studies of sex chromosomes and sex‐determining mechanisms. A recent study performed in Silene colpophylla showed that dioecy and the sex chromosomes in this species evolved independently from those in Silene latifolia, the most widely studied dioecious Silene species. The results of this study show that the sex‐determining system in Silene otites, a species related to S. colpophylla, is based on female heterogamety, a sex determination system that is unique among the Silene species studied to date. Our phylogenetic data support the placing of S. otites and S. colpophylla in the subsection Otites and the analysis of ancestral states suggests that the most recent common ancestor of S. otites and S. colpophylla was most probably dioecious. These observations imply that a switch from XX/XY sex determination to a ZZ/ZW system (or vice versa) occurred in the subsection Otites. This is the first report of two different types of heterogamety within one plant genus of this mostly nondioecious plant family.     

一个具两型子囊的齿裂菌属新种

生于蒙古栎（Ｑｕｅｒｃｕｓ　ｍｏｎｇｏｌｉｃａ）和波罗栎（Ｑ．Ｄｅｎｔａｔａ）上的齿裂菌属一新种,即异襄齿裂菌（Ｃｏｃｃｏｍｙｃｅｓｄｉｍｏｒｐｈｕｓ）。该种因子囊同时以两种状态存在而明显区别于齿裂菌属其它成员。主、副模式标本保藏于安徽农业大学森林保护教研室（ＡＡＵＦＰ）。     

出生性比研究

对 1971— 1993年云南昆明、玉溪、红河、思茅、西双版纳、大理、楚雄、丽江等 8地、州、市 66个医疗单位接生的新生儿资料进行调查 ,获取401454例新生儿性别等有关资料。发现 :( 1 )出生性比在上升 ,由 1971年的 104 .06上升到 1993年的 108.57;1974年最低 ,为 101 .11 ,1991年最高 ,为 111 .87。 23年中 ,平均每年上升 0 .47。 ( 2 )一年之中 ,新生儿出生人数的高峰期为 10、 11、 12等 3个月 ,峰顶为 11月 ,占 11 .01% ;出生性比的峰顶为 3、4、6、7、9等5个月 ,最高为 9月 ,达 109.47。 ( 3)城、乡出生性比差异显著。不论胎次 (一、二胎 )和月份 ( 8、 9两月除外 ) ,市、县城区 ,出生性比均显著高于农村。 ( 4) 1 979年以前的出生性比在101 .11— 105 .67之间 ,1980年以后的出生性比在 104 .17— 111 .87之间。 ( 5 )提出了维持性平衡的6点对策。     

云南省黄牛球虫的种类包括艾美球虫一新种的描述

国内牛球虫病已屡见报告,但关于牛球虫种类,牛群感染情况等尚未见有系统的调查。1981年2月至1982年3月,我们在云南省三个地、州、市的六县一市共调查黄牛372头,检查出12种球虫卵囊,11种为艾美球虫(Eimeria),其中包括一新种;1种为等孢球虫(Isospora)。统计了牛群和不同年龄牛的球虫感染率以及单种感染和混合感染的情况。并绘制了球虫卵囊图以兹参考。     

中国霜霉一新种

本文描述了霜霉属(Peronospora)一个新种,寄生于唇形科植物水棘针(Amethysteacaerulea L·)上的水棘针霜霉(Peronospora amethysteae Y.Li et Bai sp.nov.),有拉丁文和中文描述,并讨论了新种与同科植物上的相近种之间的区别。     

中国霜霉一新种*

本文描述了霜霉属(Peronospora)一个新种,寄生于唇形科植物水棘针(Amethysteacaerulea L·)上的水棘针霜霉(Peronospora amethysteae Y.Li et Bai sp.nov.),有拉丁文和中文描述,并讨论了新种与同科植物上的相近种之间的区别。     

中国假笼头菌一新种

假笼头菌属(Pseudoclathrus)是刘波和鲍运生(1980)根据模式种——柱孢假笼头菌(P．Cylindrosporus Liu et Bau)所建立的新属。 1987年,本文作者报道了雷公山假笼头菌(P．Leigonshancnsis Zhou et Zhang)一新种,本文再报道该属的另一新种——安顺假笼头菌Pseudoclathrus anshunensi Zhou et Zhang。本新种不同于柱孢假笼头菌之处主要是,新种具4条柱状臂,臂无脊沟,柄露于菌托外。而柱孢假笼头菌具6个柱状臂,每条臂均具纵脊沟,柄藏于菌托内;与雷公山假笼头菌的区别在于雷公山假笼头菌具5—6条薄带状的臂,臂肉桂色,担子果大,担孢子也较大,而新种具4条柱状臂,橙黄色,担子果和担孢子均较小。模式标本存放于贵州农学院植病教研组真菌标本室。     

中国玉龙蕨属一新种

植株高6-16厘米。根状茎短而直立,连同叶柄密被鳞片;鳞片暗棕色、阔披针形,边缘具长纤毛。     

GENETICS OF SEX EXPRESSION IN FRAG ARIA SPECIES

Hermaphroditism is the normal mode of sex expression in diploid species of Fragaria (Rosaceae, 2n = 14, x = 7) with one known exception, gynodioecious F. vesca L. ssp. bracteata. The polyploid species of Fragaria are all trioecious. An extensive study involving appropriate hybridization, testcrossing, selling, and backcrossing revealed that the repression of sporangia and the inhibition of sporogenesis are controlled by a single gene (or a gene complex) with at least three alleles in the sporophytes of trioecious octoploid species (2n = 56, x = 7). A male suppressor (allele F) reduces microsporangia and represses microsporogenesis completely, but it allows normal development of the stigma, style, and ovary. A female suppressor (allele M), in the absence of modifier genes, inhibits megasporogenesis and drastically reduces the number of carpels and size of receptacles. The allele H, conferring perfect flowers at an early stage of flower organogenesis, acts as an inducer of microsporogenesis in females, but leaves both microand megasporangial development intact. At the sex locus, the F allele (femaleness) is dominant to H and M and the H allele (hermaphroditism) is dominant to M (maleness). Females are exclusively heterogametic (F/H or F/M), hermaphrodites may be homo- or heterogametic (H/H or H/M), and males are homogametic (M/M). The sex gene is expressed precisely in the genetic background of octoploid × diploid hybrids of Fragaria and their derivatives and in crosses with closely related hermaphroditic diploid Pontentilla glandulosa L. Gene dosage phenomena are absent. First generation progeny of colchi-decaploids (F/F, –/–) are exclusively female, but all generations thereafter segregate in a normal diploidized manner (1:1). Application of phytohormones alters sex expression to a limited extent.     

SEX RATIO IN THE CAPE SHELDUCK

Siegfried, W. R. 1976. Sex ratio in the Cape Shelduck. Ostrich 47:113-116.

The quaternary sex ratio was found to favour females in the Cape Shelduck Tadorna cana. This finding is discussed in relation to the species' “reversed” sexual courtship and plumage di morphism.     

INDIVIDUAL SEX RATIO ADJUSTMENT IN RESPONSE TO THE OPERATIONAL SEX RATIO IN THE SOUTHERN GREEN STINKBUG

Females of the southern green stinkbug, Nezara viridula (Hemiptera: Pentatomidae), initiating copulation in a female-biased environment produced relatively more sons than females initiating copulation in a male-biased environment. Although families suffering greater mortality yielded more sons, the difference in offspring sex ratio between treatments was not due to differential mortality by sex since the distribution of family size did not vary between treatments. Female condition, indexed by female size and size of the first egg mass laid, did not vary between treatments and, therefore, apparently did not contribute to the results. Thus, it appears that the stinkbug is capable of facultative sex ratio adjustment in response to the operational sex ratio, increasing the production of sons when males are rare. In nature, overlapping generations and female-biased operational sex ratios may occur; conditions under which selection for sex ratio adjustment is most intense.     

云南省人口的性比

对云南省1990年人口普查时的性比(男:女100)进行了分析研究,发现:(1)云南省总人口的性比(105.67)比1982年人口普查时提高了2.89,比全国的(106.60)仅低0.93,开始高出“性比较为严衡状态”(1003.5:1000),为1005.3:1000,且后8年年均递升速度为1982年的18年的2.19倍。(2)景颇族的性比特别低(95.77),而汉族0—14岁儿童性比则为107.27。(3)云南“大跃进”与“国民经济暂时旧难”时期出生的人,1982年”三普”时(20—24岁)性比特别低(101.11),可1990年“四普”时(28—32岁)却达107.84。(4)城镇人口的性比(113.01),比农村入门的性比(105.67)高得多,但差异在减小,(5)全省各地人口性比不同。