SEXUAL DIFFERENTIATION OF GRIFFITHSIA (CERAMIALES, RHODOPHYTA): NUCLEAR PLOIDY LEVEL OF MIXED-PHASE PLANTS IN G. JAPONICA1

Mixed-phase plants of Griffithsia japonica Okamura spontaneously occurred in a laboratory culture. Four female plants produced tetrasporangia and spermatangia in addition to their normal female reproductive structures (bisexual/mixed-phase plants), and four male plants produced tetrasporangia as well as spermatangia (male/mixed-phase plants). To determine the nuclear ploidy level of these mixed-phase plants, relative nuclear sizes of male, female, tetrasporangial, and mixed-phase plants were measured using a microscopic image analysis system. Haploid gametophytes could be distinguished from diploid tetrasporophytes by relative nuclear sizes, with the later having nuclei twice the size of the former. Relative nuclear sizes of the mixed-phase plants were similar to those of the haploid plants. Thus, the mixed-phase plants were determined to be haploid. Haploid mixed-phase plants of G. japonica have a potential to produce male, female and tetrasporangial reproductive structures. Sex determination models are discussed to explain "haploid" mixed-phase phenomena in red algae .     

Monandrous social organization of pigtailed langurs ( Simias concolor ) in the Pagai Islands, Indonesia

Between June 1986 and October 1992, in 3 periods totaling 12 months, we studied social organization of pigtailed langurs (Simias concolor)in the Pagai Islands, Indonesia. With one possible exception, all of 20 family groups contained only 1 adult male each. Nine of them contained only 1 adult female,and 11 contained ≥2 adult females. Mean group size is 4.1 individuals. Home ranges varied from 7 to 20 ha, and population density averages 21 animals/km ² . Simias concoloris sexually dimorphic⤖n a museum sample males average 29% heavier than females, and their canine teeth are on average nearly twice the length of female canines. Combined data from several studies indicate that 60% of S. concolorgroups contain an adult pair plus young,and 40% are multifemale groupings. We sggest that any 1-male mating system that comprises a mixture of 1-female and multifemale groups in the same population should be termed monandry.     

Sex differentiation in the European eel: histological analysis of the effects of sex steroids on the gonad

The effects of sex steroids on sex differentiation in the European eel were studied. The steroids, 17α-methyltestosterone (MT) and 17α-ethynylestradiol (EE), were given in the diet to 6–8 cm elvers and to 15–18 cm and 22–25 cm yellow eels. In our rearing conditions a very large percentage of the untreated eels developed as males. No masculinizing effect of MT could be demonstrated. The EE, administered at a dose of 10 mg kg^-1 of diet to 6–8 cm elvers and 15–18 cm eels, induced ovarian differentiation in about 90 and 65% of eels respectively, while in the control <5% of females was recorded. In 22–25 cm yellow eels a moderated feminizing effect was observed.
Histological analysis of the gonads of treated eels showed that sex steroids affect the gonadal structure. The androgen stimulates hypertrophy of compact connective tissue, early differentiation of Leydig cells, Sertoli cells and early formation of the spermatic duct. Oestrogen inhibits the differentiation of these structural components and stimulates the differentiation of follicular cells and an ovarian structure.
The involvement of gonadal structural components is discussed in relation to the effect of steroid treatment and to the peculiarities of sex differentiation in the European eel.     

Peculiarities of the male urogenital apparatus of two grunt species (Teleostei, Haemulidae)

An unusual testicular structure in the white grunt, Haemulon plumieri , and the French grunt, H. flavolineatum , and a urinary exocrine gland in H. flavolineatum are described. The testes of both species are comprised predominantly of efferent ducts, with spermatogenetic tissue restricted to the gonadal periphery. The epithelial cells of the efferent ducts produce glycogen which may serve a role in the storage and nutrition of sperm. The urinary gland is a male accessory gland thought to be associated with reproduction. The gland is mesonephric in origin and the epithelial cells of the gland produce mucins which may be involved in intraspecific chemical communication.     

马尾松毛虫雄蛾触角毛状感受器的细微结构

马尾松毛虫Dendrolimus punctagus(Walker)雄蛾有一对羽毛状触角。在触角鞭节的每对侧枝的内侧(迎风面)着生许多毛状感受器。每个毛状感受器由几丁质表皮毛及位于其下的三个感觉神经原和三个呈同心排列的辅助细胞-鞘原细胞、毛原细胞和膜原细胞构成。几丁质表皮毛上有许多孔。毛腔内充满感受器淋巴液。感觉神经原发出的树状突伸入毛腔,浸浴于感受器淋巴液内。这些结构特征表明它是一种司嗅觉的化学感受器。雄蛾终生不取食,推断它的嗅觉感受器主要用以感受雌蛾释放的性外激素,帮助寻找配偶。     

马尾松毛虫雄蛾触角毛状感受器的细微结构

马尾松毛虫Ｄｅｎｄｒｏｌｉｍｕｓｐｕｎｃｔａｔｕｓ（Ｗａｌｋｅｒ）雄蛾有一对羽毛状触角。在触角鞭节的每对侧枝的内侧（迎风面）着生许多毛状感受器。每个毛状感受器由几丁质表皮毛及位于其下的三个感觉神经原和三个呈同心排列的辅助细胞──鞘原细胞、毛原细胞和膜原细胞构成。几丁质表皮毛上有许多孔。毛腔内充满感受器淋巴液。感觉神经原发出的树状突伸入毛腔,浸浴于感受器淋巴液内。这些结构特征表明它是一种司嗅觉的化学感受器。雄蛾终生不取食,推断它的嗅觉感受器主要用以感受雌蛾释放的性外激素,帮助寻找配偶     

Functional organization of the macroglomerular complex related to behaviourally expressed olfactory redundancy in male cabbage looper moths

Abstract. The neurophysiological bases for behaviourally expressed olfactory redundancy in the sex pheromone communication system of the cabbage looper moth, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), were examined by coupling the cut-sensillum extracellular recording technique with a highly specific neuronal marking method for moth peripheral receptors. In seventy-two antennal sensilla, axonal pathways of cobalt-stained neurones could be traced into the male-specific macroglomerular complex in the antennal lobe. In T. ni males this comprises five glomeruli, two of which are subdivided into morphologically, and in some instances functionally identifiable, regions. Axonal arborizations of forty-eight neurones (single stainings) showed high fidelity (98%) for containment within a specific glomerulus or glomerular subdivision, and the neuropil targeted seemed to be related to the specificity of a neurone to a particular female-emitted sex pheromone component (27-12:Ac, Z7-14:Ac, Z9-14:Ac, 12:Ac, 11–12:Ac, Z5-12:Ac), or to a behavioural antagonist (Z7-12:OH). Double (twenty-one) and multiple stainings (three) showed axons projecting into two or more glomeruli, respectively, with 100% fidelity for the component-specific glomerulus or glomerular subdivision to be targeted. We suggest that the potential for a single minor component to cross-stimulate two or more neurones within a sensillum may enable partial blends to continue to provide sensory input into all of the pheromone-processing glomeruli of the complex. Our interpretation is that redundancy occurs at the receptor level on neighbouring dendrites, and thus allows various four-component partial blends to evoke full pheromone-mediated behaviour.     

The influence of female age and host size on the sex ratio of the parasitoid Opius concolor

The sex ratio of the progeny of single females parasitizing large hosts favoured the females (sex ratio=0.26); but on small hosts favoured the males (0.73). No differences in mortality of the sexes were detected. The sex ratio was independent of female age when large hosts were used. The percentage of males observed in the progeny of the first day of female oviposition was significantly greater than the mean, irrespective of the age at which female oviposition began. When females were exposed to small hosts, a greater percentage of females was observed in the progeny from the last days of oviposition.

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Résumé L'influence de la taille de l'hôteret de l'âge de la femelle sur le taux sexuel de la descendance a été étudiée sur le parasitoïde Opius concolor Szépl.Le taux sexuel de la descendance des femelles isolées est favorable aux femelles (t.s.=0,26) quand elles ont à leur disposition des hôtes de grande taille, tandis qu'avec des hôtes petits le taux sexuel est favorable aux mâles (t.s.=0.73). On n'a pas détecté de mortalité différentielle des sexes.Les pourcentage de mâles obtenu le premier jour de ponte des femelles sur les hôtes de grande taille est significativement différent de la moyenne, indépendamment de l'âge de la femelle à ce moment. Cependant, sur des hôtes petits, bien que restant favorable aux mâles dans l'ensemble, une plus grande proportion de femelles à partir des premiers jours de ponte a pu être observée.

     

Chimpanzee predation in the Mahale mountains from August 1979 to May 1982

Fifty-four episodes of predatory behavior of wild chimpanzees were recorded in Mahale, western Tanzania, from August 1979 to May 1982. The chimpanzees most frequently hunt in two seasons, during May, and from August to December. Longer-term fecal analysis indicates that predation frequency is significantly higher in the dry than in the rainy season. The seasonality of predation might be the result of the sum of various ecological factors, at least one of which is the birth season of the prey species. Most of the prey are juvenile blue duiker, bushbuck, bushpig, red colobus, and red-tailed monkeys. Sex difference is recognized in the prey selection and in the hunting method employed. Apparent local difference in the predatory behavior between Mahale and Combe chimpanzees (in Mahale,females hunt more frequently, and blue duiker is the most frequent prey) can be understood in terms of the difference either in the observation methods or in the faunal diversity and density. Other aspects of predatory behavior also are reported.