Studies on the Reproductive Biology and Endangerment Mechanism of the Endangered Plant Manglietia aromatica

The embryogenesis, pollen germination, floral character and seed physiology of the endangered plant Manglietia aromatica Dandy were investigated. Based on this study, this species has very low seed set rate. The abortion rate of functional megaspores in all the ovules is 27.9%, the egg cell abortion rate of mature embryo sacs is up to 80%, and the germination rate of pollen grains is as low as nearly 0.01%. In addition, the floral structure appears to be another limited factor for the effective pollination of this species. The endangerment mechanism of this species seems to be comprehensive. Human's destroying actions are the direct factors that have made the population degenerate quickly; low reproductive ability and the destroyed environments are the main reasons that prevent the population from renovating and spreading. Therefore, the conservation measures suggested by this study are to research the breed technology, artificial population renovating, in situ conservation, and ex situ conservation.

Reproductive Biology of Yellowfin Tuna T. albacares in the West-Central Indian Ocean

Survey of yellowfin tuna in the west-central Indian Ocean was conducted on board of Chinese longliners during 2003,2004 and 2005,which is a part of Chinese Tuna Fishery Scientific Observer Program(CTFSOP) . The reproductive biology has been investigated. A total of 1 023 samples are collected including 417 ovaries and 606 testes. Spawning activities of yellowfin tuna have been studied for both male and female from January to June. The data showed that the average monthly sex ratio is 0.59,and the minimum length at sexual maturity is 101 cm for female and 110 cm for male respectively. Length at 50% sexual maturity is esti-mated at 113.77 cm for female and 120.20 cm for male,whereas maturation rate is 0.066 cm-1 for female and 0.091 cm-1 for male. Sex ratio by length class indicates that the proportion of male is higher than female's along with size increasing;for instance,in the group of the body length longer than 145 cm,some females have their body length from 145 to 160 cm and males have their body length at 160 cm and even longer. Statistically,yellowfin tuna has a significant seasonal reproduction.

Reproductive biology of bream Abramis brama (L.) in the lower reaches of the Irtysh River, China

The reproductive biology of bream Ahramis brama （L.） was studied from 546 fish collected from the lower reaches of the Irtysh River in Xinjiang, north-west China, from March to November 2013. The overall sex ratio （M/F） was 1.06：1, and was not significantly different from the theoretical 1：1 ratio （P〉0.5）. However, there was a dominance of males during the pre-spawning season （ 1.33 in March and 1.56 in April, P〈0.5）, while females were dominant during the peak spawning season （0.88 in June, P〈0.5）. The monthly variation in gonadosomatic index （GSI） and proportion of gonads at each macroscopic maturity stage, indicated that A. brama spawned once a year with peak spawning occurring from late May to June. The unimodal distribution of oocyte diameter each month indicated that A. brama is a single spawner, with a high degree of spawning synchronicity. The standard lengths （SLs0） and ages （As0） at first maturity for males and females, were 178 and 204 mm, and 5.6 and 6.8 years, respectively. The mean absolute fecundity （AF） was 77 311 eggs per fish, and mean relative fecundity （RF） was 162 eggs per gram of body weight （BW）. The AF ofA. brama increased linearly with increasing of gonad weight （GW）, eviscerated weight （EW） and standard length （SL）, but was not significantly correlated with age. As, A. brama in the lower reaches of the Irtysh River reaches reproductive maturity relatively late in their life span, is mature for a short period and spawns in aggregations, this fish is vulnerable to overexploitation.

Characteristics of Reproductive Biology for Larix Originating in Japan

The paper summarized the life cycle ,environmental features and distributions of Larix origination in Japan.The time of blooming and fruiting and the ways of cone collection and seeds storage were introduced.The treating methods of seeds germination and the sowing time for both Japanese larch (Larix kaempferi Carr)and Dahurian larch (Larix gmelinii var.Japonica Pilger) were discussed.

Reproductive Biology of the Male Sheath-Tailed Bat,Taphozous longimanus(Emballonuridae) From India

The seasonal chronological events of the repreductive cycle in the male sheath-tailed bat T. longimanus and changes in structure and function of accessory sex organs were studied at Varanasi (latitude: 25° N, 83°E). The first peak of spermatogenesis was ob served in September with the appearance of spermatozoa. The spermatogenic arrest in win ter dormancy (December) was followed by a second peak of spermatogenesis in January.This perbo coincides with ovulation in females. The third peak of spermatogenesis started after regression in late April, and completely regressed tubules were found after May. The cycle of accessory sex gland complex generally paralleled the testicular cycle, reaching maxi mum hypertrophy from September to January and again in late April. Thereafter, the ac cesory sex glands involuated. Spermatozoa were present in the cauda epididymidis through out the year. The reproductive cycle in family Emballonuridae varies with changes in lati tude, and this was so even in members of the same species. The presence of spermatozoa in the cauda epididymidis throughout the year is an interesting feature in the reproductive cy cle. Temperature and photoperiod do not play a regulatory role in reproduction in T.longimanus

Biology and Breeding of Snail Eater Pangasius （Pangasius conchophilus） in Thailand： An Overview

Snail eater pangasius （Pangasius conchophilus） is a freshwater fish species indigenous to Mekong-Chaophraya Basin, and is an economic fish in Thailand. This paper reviews some Thai research papers for referable benefit of international countries. The relationships of fecundity with body length and weight of wild population are related （F = 0.54L3339, F = 435.41W^S399）. Length-weight relationships of both sexes are W = 0.0059L3044s. Sex ratio is 1：1 and spawning season starts during March to June, the egg is adhesive demersal. Average mature size of both sexes are from 40-60 cm TL and 1,100-2,900 g. Effect of 3 types of hormone on induced ovulation, including HCG, pituitary gland, and buserelin in combination with domperidone are not signiticantly different （P 〉 0.05）. Hatching occurs in 24-25 hours after fertilization. The hatching percentage is 80%. Nursing and feeding strategies are also reviewed in this paper.

Reproductive Biology of the Striped Seabream Lithognathus mormyrus （Linnaeus, 1758） from AI-Haneah Fishing Site, Mediterranean Sea, Eastern Libya

Reproductive biology of L. mormyrus was studied using monthly samples totaling 224 fish obtained from AI-Haneah fishing site, eastern Libya Mediterranean Sea. Lengths of the examined fish ranged between 11.5 cm and 23.4 cm. Corresponding weights were 24.5 g and 160.8 g. The minimum values of the condition factors, KF and Kc, were 1.38 and 1.21 at the average fish length of 12.4 cm. These values increased with increases in length until they reached maximum values of 1.59 and 1.41 at the length of 22.1 cm. The high values of KF and Kc, Gonado-Somatic Index and oocyte diameter maintained during May, June, July, and August and the monthly changes in gonadal condition, indicated that summer was the breeding season of L. mormyrus. The oocyte diameter ranged between 379± 25.3 μ and 1,511 ± 143.3μ （n = 76） with an average of 895 ± 111.3 μ. The sex ratio was in favor of females during all months of the study. The overall sex ratio was 1 ： 1.52. Length at first maturity, Ls0, for L. mormyrus was found to be 14.15 cm for males and 14.45 for females. Overall average of absolute fecundity was 4,342±557 egg per fish （n = 45）. The overall average of relative fecundity was 234± 181 egg per cm. Absolute fecundity increased with increasing fish length.

The Influence of Environmental Factors on the Population Structure and Reproductive Biology of Idotea balthica basteri (Isopoda, Valvifera) of the Bizerte Lagoon (Northern Tunisia)

The reproductive biology of a natural population of Idotea balthica basteri (Pallas, 1772) collected from Menzel Jemil (Bizerte lagoon, Tunisia) was monthly studied from October 2009 to October 2010. Besides water temperature, salinity, turbidity, pH, and dissolved oxygen were measured. Based on the state of differentiation of individuals, the population was divided into 8 categories. Their numbers depend on the one hand to intrinsic factors imposed by the specimens and the structure of the population themselves, and to extrinsic factors due to the variability of environmental conditions on the other hand. Females were morphologically recognisable at smaller size than males. Reproductive activity, which was reflected through the presence of ovigerous females and juveniles, underwent fluctuations throughout the year, but it was continuous. Moreover, salinity, temperature, nitrates, and plant biomass have a noticeable effect on the fecundity and fertility. The Principal Component Analysis also confirmed that the richness of the water in nitrates would be favorable to fecundity and fertility of Idotea balthica basteri. However, higher phosphate concentrations, in April and May seem to have a positive effect on the sex ratio. Otherwise, the temperature would be responsible for increasing the percentage of ovigerous females.

The structures of floral organs and reproductive characteristics of an ornamental bamboo species,Pleioblastus pygmaeus

As a woody grass,bamboo has special reproductive habits with an extremely long vegetative phase.Pleioblastus pygmaeus is a kind of ornamental dwarf bamboo species with high ecological and economic value in China.There was no documentary record of the flowering of P.pygmaeus until 2015,which bloomed in the Bamboo Garden of Nanjing Forestry University.Generally,bamboo plants rarely bear fruit or have a low seed setting rate,but this species has a high seed production.This study explores developmental reasons using anatomical methods.The process of flower bud differentiation and a series of important reproductive development processes including anther wall development,microsporogenesis,megasporogenesis,male and female gametophyte development,and embryonic development were investigated sequentially.Each stamen contained three tetrasporangiate anthers and the development of anther wall was of Monocotyledonous type.The microspores finally matured into 3-celled pollen grains by two successive mitoses.The pistil was composed of three carpels,with an anatropous,tenuinucellate and bitegmic ovule in a single ovary.The formation of embryo sac belonged to Polygonum type.With three mitoses,functional megaspore developed into the embryo sac with eight nuclei within seven cells.The development of stamen and pistil was synchronous in the same floret.The development of embryo followed Grass type and the development of endosperm belonged to Nuclear type.The development of endosperm was earlier than that of embryo.The study enriches basic knowledge of reproductive biology of bamboo plants and is of great fundamental significance to furtherly explore flowering mechanism of P.pygmaeus and to cultivate bamboo plants sustainably.

Development of Plant Embryology in China

The development of plant embryology in China can be roughly divided into three stages: (1) the initial stage, (2) the stage of establishing plant embryology as a branch of plant sciences, and (3) the stage when plant embryology evolves into plant reproductive biology with its vigorous development. It is in the third stage that research work in this field in China has developed rapidly and many of the significant achievements obtained are described in more details in this review. Researches of experimental embryology are not included in this paper.

Reproductive characteristics of Psilorhynchus homaloptera Hora and Mukerji,1935 (Cyprinidae: Psilorhynchidae) in the lower Yarlung Zangbo River,Tibet

Psilorhynchus homaloptera mainly inhabits turbulent waters in the lower reach of the Yarlung Zangbo River,Tibet,China,and it is the only species of Psilorhynchus in China.However,many important aspects of its biology remain poorly documented,which hinders the conservation eff orts.Therefore,we studied its reproduction using 801 specimens from the Motuo sector of the lower Yarlung Zangbo River from December 2015 to November 2016.The sex ratio was 0.68꞉1(male꞉female)for the overall population.Females reached a larger total length and weight(134 mm and 18.6 g)than males did(113 mm and 12.2 g).Lengths at maturity were estimated 80.0 mm for males and 93.1 mm for females.Our analyses of gonad development and the size distribution of oocytes suggest that P.homaloptera is a single spawner with the peak spawning period between September and October.Furthermore,the estimated mean absolute fecundity was 557±204 eggs per fish,and mean relative fecundity was 50.9±10.9 eggs per g of female weight.The fecundity of P.homaloptera increased linearly with increasing total length,total weight,ovary weight,and age.This study on the reproductive biology of P.homaloptera demonstrates that the fish was in a vulnerable state due to the increasing anthropogenic activities in the lower Yarlung Zangbo River.

Reproductive toxicity assessment of benzo[a]pyrene in the marine polychaete Perinereis nuntia

Benzo[a]pyrene （B[a]P） is an increasingly present marine environmental pollutant, yet our understanding of the long-term consequences of reproductive toxicity in marine benthic polychaetes remains limited. To test the reproductive toxicity of B[a]P on polychaetes, Perinereis nuntia was exposed to B[a]P-contaminated artificial seawater and sexual maturation, the sex ratio, number of eggs spawned, fertilization and hatching rated, as well as vitellogenin （VTG） mRNA expression levels were analyzed. A low concentration of B[a]P （2.5 gg/L） had no effects on the rate of sexual maturation, spawning, or fertilization but significantly increased the sex ratio （female： male） from 1.6±0.15：1 to 2.3±0.18：1, inhibited hatching rate by 27%, and significantly increased VTG mRNA expression level by 3.7-fold following a 60-day exposure, compared with those in the solvent controls. A higher concentration of B[a]P （25 μg/L） caused more serious effects; sexual maturation, fertilization success, and hatching decreased by 31%, 17% and 46%, respectively, and the sex ratio （female： male） and VTG mRNA gene expression level increased by 54% and 7.1-fold, respectively. These results demonstrate that sublethal concentrations of B[a]P negatively affect reproductive performance of the sandworm P. nuntia.

Reproductive cycle of Ophiopholis mirabilis (Echinodermata: Ophiuroidea) in Zhangzi Island area, northern Yellow Sea

Ophiopholis mirabilis is a common species with a high population density on the western coasts of the northern Pacifi c Ocean.The number of O.mirabilis has been increasing recently in the scallop aquaculture zone(the Zhangzi Island area,northern Yellow Sea)in China.To explore the mechanism of its population variation,the reproductive cycle of O.mirabilis was investigated in this area(39°04′N;122°51′E)from February 2017 through January 2018 and determined by the monthly gonad index(GI),histological examinations of the gonads and the oocyte size-frequency distribution.O.mirabilis had a clear annual reproductive cycle that was synchronous between males and females.Sea temperature and food availability played important roles in O.mirabilis reproduction.The GI value was less reliable for determining reproductive activity in O.mirabilis because the nutritive tissues within the gonads may be utilized to synthesize gametes,leading to a decrease in GI during maturation.The histological results also show that abundant nutritive phagocytes were present in the gonads of O.mirabilis,which,together with the germ cells,aff ected the weight of the gonads.In addition,the mature oocytes of O.mirabilis were relatively small(75–150μm),indicating that the larval development was planktotrophic.This study provided insights into the reproductive patterns and biology of O.mirabilis and is an essential basis for the quantity control of this species in aquaculture areas.

Inheritance of the Number of Ovules per Ovary and Selection of Cacao Genotypes

We have characterized the number of ovules per ovary (NoOV) in cacao plants originated from crossing the clones CCN 51 and TSH 1188 (segregating progeny) and determined the heritability of this characteristic in order to select plants with higher NoOV in this progeny. The NoOV was calculated as the average of 10 flowers per plant and ranged from 44.8 to 58.6 between the six clones (two parents and four clones belonging to their genealogy). In the progeny (n = 209 plants) the NoOV averaged 54.3 (range 44.1 to 67.8). The NoOV was distributed uniformly among the progeny indicating that this trait is conditioned by polygenes. Its heritability was estimated at 67.7%. The 32 plants with NoOV similar or superior to the genitor CCN 51 (highest amount among clones) were selected for use in the genetic improvement program. We showed that this population is suitable for genetic mapping, molecular marker identification and selection of superior cacao genotypes.

Study of the growth,reproductive biology and abundance for invasive shrimps Palaemon elegans Rathke from Garmat Ali river Basrah,Southern Iraq

Objective:To describe the growth,reproductive biology and abundance of the population of invasive shrimps Palaemon elegans(P.elegans)in one of the branches of Garmat Ali river at Basrah,Southern Iraq.Methods:Monthly samples of the prawn P.elegans were collected with a bottom hand net(40 cm,0.5 mm mesh)hauled over a distance of 10 m.A simple random sampling was conducted monthly between December 2012 and November 2013.Results:Seasonal changes were observed in the composition of the population of the species during the study year with the highest abundance in 2013 and the lowest abundance for the males was reported in January and for the females occurred in June.Salinity showed a significant correlation with the abundance of shrimps at the sampling site.The largest female measured 67.90 mm while the corresponding value for males was 61.31 mm.The proportion of ovigerous adults rose during spring season to peak on about July and ovigerous prawns were taken in all months of the year.The sex ratio indicated a preponderance of females over males in all months in the study period.Each females produced around 36-1324 eggs and the incubation period lasted for 11-14 days at 17-29°C.Conclusions:The results of the present study indicate that this species has a wide distribution range,high density,and great reproduction potential.This study reveals the lack of researches on this species in environments of Shatt Al-Arab river and its branches.Thus,P.elegans has most likely formed a permanent population in all the brackish waters in Basrah area.

Multiple mating by both sexes in an invasive insect species,Aethina tumida(Coleoptera:Nitidulidae)

Multiple mating by both sexes is common among sexually reproducing animals.Small hive beetles(SHB),Aethina tumida,are parasites of bee nests endemic to sub-Saharan Africa and have become a widespread invasive species.Despite the considerable economic damages they can cause,their basic biology remains poorly understood.Here we show that male and female small hive beetles can mate multiple times,suggesting that costs for mating are low in this species.In an invasive A.tumida population in the United States,a combination of laboratory experiments for males and paternity analysis with eight polymorphic DNA microsatellite markers for field-caught females were used to estimate the number of mating by both sexes.The data show that females and males can mate multiple times—females mated with up to eight males,whereas males mated with at least seven females.The results also showed that A.tumida displayed a skewed paternity,although this was not consistent among the tested females.Thus,first or last male advantage seem to be unlikely in A.tumida.Our observations that individuals of both sexes of A.tumida can mate multiple times opens new research avenues for examining drivers of multiple mating and determining the role it may play in promoting biological invasions.

Conservation aquaculture of Ompok bimaculatus (Butter catfish), a near threatened catfish in India

The butter catfish,Ompok bimaculatus,belonging to the silurid family,is widely regarded as an important food fish for aquaculture diversification in India.Furthermore,the species poses a threat due to habitat degradation and other anthropogenic factors,and has been categorised as“near threatened”,therefore,its culture promotion is warranted.To establish a successful breeding programme,a precise understanding of the life history,and biology(reproductive/feeding)of the fish will assist hatchery managers and researchers.Studies in these areas have been undertaken by several groups over the years,but without much coherence,the data are still fragmented.Few attempts on the culture attributes of this catfish have been performed under both mono-and polyculture systems to bring about parallel promotion through aquaculture in a larger part of the subcontinent.Highlighting this,we have tried to analyse and present a consolidated account of the morphological characteristics,feeding habits,reproductive biology,early developmental ontogeny,and culture potentials of O.bimaculatus in India.This review was also prompted by the paucity of information on the cultural aspects of the species.Additionally,based on the reported studies,future directions and perspectives of the culture promotion of the species are proffered to ensure future research initiatives.

Signaling in Pollen Tube Growth： Crosstalk, Feedback, and Missing Links

Pollen tubes elongate rapidly at their tips through highly polarized cell growth known as tip growth. Tip growth requires intensive exocytosis at the tip, which is supported by a dynamic cytoskeleton and vesicle trafficking. Several signaling pathways have been demonstrated to coordinate pollen tube growth by regulating cellular activities such as actin dynamics, exocytosis, and endocytosis. These signaling pathways crosstalk to form a signaling network that coordinates the cellular processes required for tip growth. The homeostasis of key signaling molecules is critical for the proper elongation of the pollen tube tip, and is commonly fine-tuned by positive and negative regulations. In addition to the major signaling pathways, emerging evidence implies the roles of other signals in the regulation of pollen tube growth. Here we review and discuss how these signaling networks modulate the rapid growth of pollen tubes.

The Ins and Outs of the Rice AGAMOUS Subfamily

Genes of the AGAMOUS subfamily have been shown to play crucial roles in reproductive organ identity determination, fruit, and seed development. They have been deeply studied in eudicot species and especially in Arabidopsis. Recently, the AGAMOUS subfamily of rice has been studied for their role in flower development and an enormous amount of data has been generated. In this review, we provide an overview of these data and discuss the conservation of gene functions between rice and Arabidopsis.

The Arabidopsis LFR Gene Is Required for the Formation of Anther Cell Layers and Normal Expression of Key Regulatory Genes

The anther is the male reproductive organ in flowering plants. Although some genes were reported to be involved in anther development, the molecular mechanisms underlying the transcriptional regulation of these genes is unclear. Ifr-2 （leaf and flower related-2）, the null allele of Arabidopsis thaliana LFR （LEAF AND FLOWER RELATED）, was male-sterile. The anthers of Ifr-2 plants were defective in sporogenous cell formation, tapetum development, and pollen development. In agreement with these phenotypes, expression studies showed that LFR was expressed in all cell layers of the anther, and that expression was particularly strong in the tapetal cells and pollen grains, Quantitative RT-PCR analysis revealed that LFR is required for the normal transcription of some anther development-related genes, such as AMS, CALS5, and DYT1, MS1 and MS2, and ROXY2. Genetic analysis showed that SPL was epistatic to LFR while LFR was epistatic to DYT1. We propose that LFR may be a crucial component in the regulation of a genetic network that modulates anther development.