Viability of maternally heat-stressed mouse zygotes in vivo and in vitro

Mammalian preimplantation embryos are susceptible to heat stress. This present study examined how maternal heat stress affects the development of mouse zygotes in vivo and in vitro. In Experiment 1, zygotes collected from female mice that were heat‐stressed for 12 h on day 1 of pregnancy were cultured in vitro. Maternally heat‐stressed zygotes developed normally to the two‐cell stage, but the majority of embryos failed to develop into morulae or blastocysts. In Experiment 2, pregnant mice were heat‐stressed on day 1 or from day 1 to day 3 of pregnancy. The number of living fetuses on day 14 of pregnancy was lower in heat‐stressed mice than in non‐stressed mice, but the difference was significant only in successively heat‐stressed mice. These results demonstrate that maternally heat‐stressed zygotes have reduced in vitro viability, but this phenomenon does not necessarily lead to embryo loss in the maternal environment.     

Hermetically Sealed Storage of Cereal Seeds and its Influence on Vigour and Germination

Investigations of the influence of hermetic cereal seed storage on germination were carried out in the laboratory of the Faculty of Agriculture in Osijek (Croatia) over 5 years (1992–96). Seeds of four species (winter wheat, winter barley, spring oat, and maize) were stored in hermetic glass containers at an air temperature of 20 °C and a relative humidity of 65 %. The moisture level in stored seeds was 13 %. After 5 years, statistically highly significant associations (P < 0.01) were found between storage longevity (five researched years) and seed germination of the four cereals. Germination of all investigated cereals was high (between 97.25 % for maize and 93 % for winter wheat) after harvest. The germination level decreased for all cereals, on average by 38 %, over the 5 years of storage. The highest germination values were found for wheat seeds (84.75 %) and the lowest germination values for maize seeds (36.0 %). The results showed that germination of all investigated cereals seeds was negatively correlated with storage longevity. The differences in germination found amongst the cereals were statistically highly significant (P < 0.01).     

Semen alterations in porcine rubulavirus-infected boars are related to viral excretion and have implications for artificial insemination

Porcine rubulavirus (PoRV), also known as blue eye disease (BED) of swine, causes respiratory and reproductive problems in pigs at several developmental stages. To study the effect of PoRV infection on semen production, five boars were infected with 1 x 10(6) TCID(50)/ml of PoRV strain PAC-3 and evaluated for 59 days post inoculation (DPI). Infected boars developed reproductive tract pathology that included swelling of the testes and epididymides. Analysis of the semen showed that the infection had little effect on semen production in four animals, but semen from one boar showed severe alterations in sperm concentration, motility, and morphology. When motility was analyzed in BTS-diluted semen after 24, 48, or 72 h, alterations were detected in all boars. Furthermore, viral antigen was detected in semen, the seminal plasma fraction, or sperm fraction from all boars. These results showed that PoRV is excreted via semen and, therefore, artificial insemination is a potential route of dissemination.     

Meiosis and pollen grain viability in Helianthus mollis,Helianthus salicifolius,Helianthus maximiliani and their F1 hybrids with cultivated sunflower

Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined.Hybrids were obtained from eight combinations, with 3–15 F₁ plants per combination. The F₁'s exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F₁ hybrids. At diakinesis, bivalents (62.7–97.9% of meiocytes), univalents (0–31.23%), and multivalents (3.84–7.68%) were detected. At anaphase I, chromosome bridges were detected in 6.77 to 11.44% of meiocytes. Fast chromosomes in metaphase I, and lagging chromosomes in anaphase I and telophase II were evidenced in a high percentage of meiocytes.     

Abscisic acid, gibberellin and cell viability in cereal aleurone

The aleurone layer of cereals is a secretory tissue whose activity is regulated by abscisic acid (ABA) and gibberellins (GAs). Whereas GA triggers enzyme synthesis and secretion and initiates a program that culminates in cell death, ABA prevents enzyme production and cell death. Reactive oxygen species (ROS) are key players in regulating cell viability and GA sensitizes the aleurone cell to ROS. Sensitivity of GA-treated cells results in part from a reduction in steady-state amounts of mRNAs encoding enzymes that scavenge ROS. mRNAs encoding catalase, superoxide dismutase and ascorbate peroxidase are almost undetectable in aleurone layers 24 h after incubation in GA. For layers incubated in ABA, however, the amounts of these mRNAs increase. Western blotting and enzyme activity assays confirm that GA but not ABA reduced the amount and activity of ROS scavenging enzymes (Fath et al., 2001b). Substantial amounts of ROS are produced by enzymes engaged in lipid metabolism, and by the electron transport chain in the mitochondria. Aleurone layers contain abundant stores of triglycerides and ROS are produced as these lipids are rapidly converted to sugars. We hypothesize that the ROS produced in GA-treated aleurone cells bring about cell death by disrupting the plasma membrane. Aleurone cells incubated in ABA, on the other hand, are better able to maintain redox balance. ABA does not initiate rapid triglyceride metabolism, and the activities of ROS-scavenging enzymes remain high in ABA-treated cells. We conclude that GA initiates a metabolic cascade in aleurone cells that results in death from ROS. ABA maintains viability by keeping ROS under control. This revised version was published online in August 2006 with corrections to the Cover Date.     

Gibberellins as gametocides for the common onion (Allium cepa L.). III. GA4+7 and pollen viability

Summary The gametocidal effect of GA₄₊₇ in onion is strong in respect of pollen production but very weak or absent in respect of pollen viability. Large scale application of GA₄₊₇ for the production of onion hybrid seed is still impossible because of low seed yield and high costsof required chemicals. On a small scale, however. GA₄₊₇ can be used very well to emasculate breeding material.Because of switching over to the gibberellin terminology of plant physiologists, this title slightly deviates from that of the two previous articles.     

Comparison of different pollen viability assays to evaluate pollen fertility of potato dihaploids

Summary The main obstacle in breeding potato (Solanum tuberosum L.) dihaploids is the severe limitation of male fertility. To determine pollen viability assays that correlate well to fertility in crosses, results of five different pollen viability assays were compared by correlation analysis with fruit and seed set characters in test crosses, and to pollen tube growth in situ (PL-test). The methods used were: staining the pollen cells with carmino acetic acid (CAA-test); in vitro pollen germination (PG-test); and detection of pollen staining rates after incubation with fluoresceine diacetate (FDA-test), 2-3-5-triphenyle tetrazolium chloride (TTC-test), and 5-bromo-4-chloro-3-indolyle--galactoside (X-Gal-test).The results of test crosses and pollen tube growth in situ correlated with the results of all other assays with the following ranking, from highest to lowest: enzyme activity assays (X-Gal-test, FDA-test, TTC-test), in vitro pollen germination (PG-test), and pollen staining by CAA. The newly developed X-Gal-test for monitoring -galactosidase activity showed the least variation of all assays investigated. Thus, this highly reproducible simple procedure is recommended for male fertility screening.Abbreviations B/F Berries obtained per 100 flowers - CAA Carmino acetic acid - FDA Fluoresceine diacetate - PG Pollen germination rate in vitro - PL Pollen tube growth in situ - S/B Seeds per berry - S/F Seeds per pollinated flower - TTC 2-3-5-triphenyle tetrazolium chloride - X-Gal 5-bromo-4-chloro-3-indolyle--galactoside     

磁场处理水对蔬菜种子发芽影响的初步研究

本研究采用0.025T、0.05T、0.1 T(T:特斯拉)剂量的磁场处理水对结球甘蓝、白尖叶莴苣和短叶十三萝卜的种子进行浸种处理.结果表明:不同剂量的磁场处理水浸泡蔬菜种子与对照(非磁场处理水浸泡种子)在发芽率和发芽势上存在显著的差异,其中以0.1T磁场处理水浸泡蔬菜种子的效果为最好.     

玉米与玉米近缘种可杂交性研究

本文对玉米与其近缘种及它们的杂交或回交后代的可杂交性进行了研究。结果表明，玉米近缘种的多数材料都能与玉米杂交结实，它们的杂种F1均表现出强的杂种优势和光敏反应；远缘杂交亲和性的母本效应较大，且与物种间遗传距离直接相关。此外，还对玉米近缘材料在玉米遗传育种中的应用进行了探讨。     

TTCH定量测定辣椒种子的活力及活力丧失原因的探讨

本文以辣椒种子为材料,测定了不同贮存年限的辣椒种子发芽率,用TTCH测定了其活力,结果表明活力指标与发芽率相关极显著,华椒1号的相关系数达0.8912,华椒17号的相关系数达0.9277。实验表明辣椒种子活力下降的内在因素是膜的破坏、活性物质减少及毒素积累等因素引起的。