Pollination success in a population of dioecious rain forest trees

Pollination success in female trees was determined for a population of Neolitsea dealbata (R. Br.) Merr., a locally abundant dioecious tree pollinated by small, unspecialized insects in northern Queensland rain forest, Australia. The population consisted of a clustered group of trees with a mean male-to-female distance of 4.5 m and more isolated individuals, including females more than 90 m away from the nearest pollen source. A map of all reproductive trees was produced to determine accurate male-to-female distances. The size of the pollen source available to females was defined as a function of the distance to the nearest ten male trees and their sizes (male neighbourhood index). The rate of pollen movement to females was measured by counting pollen tubes (and the number of tubes per style) in female trees 6 days after the commencement of population flowering. The pollination rate decreased steeply to less than half when the nearest male was only 6.5 m away. Although pollen reached a female 330 m away from the nearest pollen source, only 10% of receptive flowers had been pollinated. The short flowering period (2–3 weeks) combined with the the slow rate of pollen movement means that a large proportion of flowers in isolated trees are unpollinated, confirming an earlier finding that isolated females set fewer fruits than gregarious females. The reliability of pollen transfer to females was determined by quantifying insects and their pollen loads trapped at female trees with a range of male neighbourhood indices. Quantities of insects and pollen were significantly correlated with the size of the male neighbourhood index, indicating a strong density-dependent response by vectors to flowering. Pollen was also collected from insect visitors to non-flowering trees. Females with large male neighbourhood indices received more pollen than non-flowering trees with equivalent male neighbourhood indices. However, when the male neighbourhood indices were small for both female and non-flowering trees, the changces of pollinators encountering female and non-flowering trees were similar, suggesting random movements of pollinators in sparse-flowering sub-populations. The dioecious breeding system, brief, synchronous flowering period, clustered population structure and random, opportunistic foraging behaviour of vectors interacted in a way that reduced reproduction in relatively isolated trees. These results demonstrate a mechanism for differential breeding success between trees in natural populations and emphasize the possible impact of logging regimes on pollen flow between trees. Large interconspecific distances in species-rich environments may have been a factor in the selection for synchronous flowering between trees in outcrossing tree species with generalist insect pollinators.     

Assessment of cytoplasmic differences of near-isonuclear male-sterile lines in pearl millet

Four near-isonuclear polycytoplasmic versions of 81A and two of Pb 402A male-sterile lines of pearl millet (Pennisetum typhoides) were used in factorial matings with five inbred male testers in different combinations in three sets. The cytoplasmic differences were studied for several agronomic traits using mean values and general combining effects (gca) of male-sterile lines, and specific combining ability effects of hybrids. The fertility/ sterility behaviour of different male-sterile lines in crosses with common male parents was also studied. Significant differences among near-isonuclear polycytoplasmic lines were observed in mean values for a few traits such as plant height, leaf length and peduncle length, but the differences for combining ability were more pronounced. The A₃ cytoplasm was a better general combiner than the A₂ cytoplasm for grain yield and both A₂ and A₃ cytoplasms were better general combiners for leaf length and peduncle length. In addition, superiority of A₃ cytoplasm for gca was observed for plant height and ear characters over the A₂ cytoplasm in set II. A differential behaviour of cytoplasms, both in combination with a common pollinator and across pollinators, was observed for several traits. The results provide evidence for the distinctiveness of different cytoplasmic sources in pearl millet and for the influence of cytoplasmic factors on the phenotypic expression of nuclear genes. A diversification of male sterility sources in the breeding of pearl millet hybrids is suggested.     

长白落叶松生殖生物学特性研究──Ⅰ．球花芽分化与早期发育

本文研究了长白落叶松（ＬａｒｉｘｏｌｇｅｎｓｉｓＨｅｎｒｙ）大小孢子叶球的分化及其分布规律．获得如下结果：（１）６月下旬芽鳞形成期终止,７月初进入小孢子叶分化期,７月未至８月上旬小孢子叶分化期结束．８月上旬进入小孢子囊分化期,８月下旬出现造孢细胞,９月中旬形成小孢子母细胞．１０月底小孢子母细胞保持在细线期阶段,小孢子叶球进入冬季休眠期．（２）９月初苞片原基开始形成,９月中旬珠鳞原基形成;１０月上旬出现胚珠原始体,１０月下旬大孢子母细胞形成,１０月底大孢子叶球芽进入冬季休眠．（３）小孢子叶球芽主要分布在树冠的中、下部．数量上远远大于大孢子叶球芽的数量,约为大孢子叶球芽的１９倍。大孢子叶球芽主要集中分布在树冠中部,而且树冠下部多于树冠上部。     

Effects of D2O on permeation and gating in the Ca2+-activated potassium channel fromChara

We studied the effects of H₂O/D₂O substitution on the permeation and gating of the large conductance Ca²⁺-activated K⁺ channels inChara gymnophylla droplet membrane using the patchclamp technique. The selectivity sequence of the channel was: K⁺>Rb⁺≫Li⁺, Na⁺, Cs⁺ and Cl⁻. The conductance of this channel in symmetric 100mm KCl was found to be 130 pS. The single channel conductance was decreased by 15% in D₂O as compared to H₂O. The blockade of channel conductance by cytosolic Ca²⁺ weakened in D₂O as a result of a decrease in zero voltage Ca²⁺ binding affinity by a factor of 1.4. Voltage-dependent channel gating was affected by D₂O primarily due to the change in Ca²⁺ binding to the channel during the activation step. The Hill coefficient for Ca²⁺ binding was 3 in D₂O and around 1 in H₂O. The values of the Ca²⁺ binding constant in the open channel conformation were 0.6 and 6 μm in H₂O and D₂O, respectively, while the binding in the closed conformation was much less affected by D₂O. The H₂O/D₂O substitution did not produce a significant change in the slope of channel voltage dependence but caused a shift as large as 60 mV with 1mm internal Ca²⁺.     

Influence of A1 cytoplasmic substitution on the downy-mildew incidence of pearl millet

Large-scale cultivation of pearl millet [Pennisetum glaucum (L.) R. Br. F₁ hybrids in India has led to increased incidence of downy-mildew (Sclerospora graminicola). There is concern that the A₁ male-sterile cytoplasm used in all the hybrids released so far is responsible for this increase. The influence of A₁ malesterile cytoplasm on downy-mildew incidence in pearl millet was studied by comparing the disease reaction of 40 pairs of F₁ hybrids, each pair carrying respectively a₁ male-sterile and normal B cytoplasm. Mean downy-mildew incidence was similar in the hybrids carrying either A₁ male-sterile or B cytoplasm. The general combining ability of lines with and without A₁ cytoplasm was found to be similar for downy-mildew incidence. These results indicated that in pearl millet A₁ cytoplasm is not associated with increased downymildew incidence. The possible danger of using only one source of cytoplasm has been briefly discussed.     

The second phantom aquatic leaf beetle in Japan: Macroplea mutica rediscovery in the wetlands (Coleoptera: Chrysomelidae)

Wetland biodiversity is currently declining on a global scale. Wetland biodiversity understanding is critical for determining the wetlands' conservation value. In this study, Macroplea Samouelle, 1819 (Coleoptera: Chrysomelidae) was discovered in Aomori Prefecture, Honshu Island, Japan. Only two Macroplea species have been recorded in Japan, M. japana (Jacoby, 1885) and M. mutica (Fabricius, 1792). Macroplea japana had been unrecorded for 60 years before being rediscovered in Honshu Island in 2022, and a single adult M. mutica female was discovered in Hokkaido Prefecture in 2003. The discovered individuals were concluded to be M. mutica based on morphological and molecular analyses. Although morphological differences were observed with the Eurasian M. mutica individuals, the male genitalia was nearly identical to M. mutica. For the molecular phylogenetic analysis based on COI and 28S sequences, Macroplea individuals in Japan were clustered with M. mutica on the Eurasian Continent. This is the first record of this species on Honshu Island (and the second in Japan), as well as the first record of adult males. This species would require conservation policies and additional distributional surveys.     

Chemical agents that inhibit pollen development: effects of the phenyl-cinnoline carboxylates SC-1058 and SC-1271 on the ultrastructure of developing wheat anthers (Triticum aestivum L. var Yecora rojò)

Summary Phenylcinnoline carboxylate compounds SC-1058 and SC-1271 cause complete male sterility in wheat when applied at suitable dosages at the pre-meiotic stage of anther development. Anthers from treated and untreated plants were compared using light and electron microscopy from the pre-meiotic stage through the formation of nearly mature pollen. Overall anther development is gradually slowed in treated plants and pollen development is generally arrested in the late prevacuolate or early vacuolate microspore stage, although the first pollen mitosis does sometimes occur. The sporopollenin-containing exine walls are thinner, and show abnormally developed foot and tectum layers with sparse connecting baculi. Microspore cytoplasm degenerates and the cells eventually collapse. At the early, prevacuolate, free microspore stage treated tapetal cells hypertrophy, expanding into the locule. They contain abnormally large vacuoles that appear to form from the fusion of secretory vesicles, and some vacuoles contain electrondense deposits. The sporopollenin-containing orbicular wall and Ubisch bodies are retarded in their development and are structurally deformed. Acetolysis of whole anthers and of thick sections shows that the sporopollen-in-containing structures of treated materials are greatly reduced in thickness and are less rigid than in the control. We conclude that application of these compounds causes interference with the secretory function of tapetal cells which supplies sporopollenin cell-wall polymers to the exine of the microspores and to the tapetal orbicular wall and associated Ubisch bodies. Interference with the tapetal secretion of other nutrients required for microspore development is strongly suggested.     

Ameliorative effects of nano Moringa on fluoride-induced testicular damage via down regulation of the StAR gene and altered steroid hormones

Fluoride is a common environmental contaminant that has harmful effects on human health when it is present in high concentrations. Fluoride enters the bloodstream after being absorbed by the gastrointestinal system when fluoride-contaminated groundwater is consumed by people. The aim of the present study was to determine whether polyphenol-rich nano Moringa oleifera (NMO) could protect rat testicles from sodium fluoride (NaF) damage by evaluating sperm quality, sex hormones, testicular oxidative status, histopathology, and StAR gene expression. Twenty-eight adult Wistar rats were divided equally and randomly into four groups: group one received distilled water; group two received NMO at a dosage of 250 mg/kg/body weight; group three received NaF at a dosage of 10 mg/kg/body weight; and group four received NaF and NMO. The rats were orally administrated daily for a duration of eight weeks. The study's findings demonstrated that, in comparison to rats exposed to NaF alone, co-administration of NMO and NaF enhanced sperm motility and viability, decreased sperm morphological changes, restored the balance between oxidant and antioxidant status, improved testosterone and dehydroepiandrosterone, improved testicular histology, raised the Johnson score, and upregulated the StAR gene in testicular tissue. These findings show that NMO is promise as a prophylactic medication against sodium fluoride-induced testicular damage because administration of NMO had no adverse effects and enhanced reproductive health.     

黄山雄性短尾猴换群行为的研究

１９８６至１９９２年对安徽黄山一群短尾猴连续进行７年的换群行为研究表明：雄性的换群行为发生在临近交配期开始前后,大多数为成年个体;这些个体与换群前的顺位无关,且未受到迁入新群的其它个体更多的攻击,迁入雄体还倍受雌体青睐。据此推测,外群雌性的性吸引是雄性短尾猴换群的直接原因。雄性短尾猴换群的结果,降低了种群的近亲繁殖率,增加了不同种群间的基因交流,对种群遗传多样性的保存和发展具有重要意义．因此,进化选择压力有利于换群行为的发展。