Some coat protein constituents from strawberry latent ringspot virus expressed in transgenic tobacco protect plants against systematic invasion following root inoculation by nematode vectors

The coding sequences in RNA2 for the coat proteins (CP) of strawberry latent ringspot virus (SLRSV) were modified and amplified using polymerase chain amplification reactions (PCR) to facilitate their expression inAgrobacterium tumefaciens-transformedNicotiana tabacum Xanthi-nc. The coding sequences for the smaller capsid protein (S, 29kDa) and that for the theoretical precursor of L and S (P, 73kDa) had ATG initiation codon sequences added at the 5-proximal Ser/Gly (S/G) cleavage site in the unmodified sequence. The sequence coding for the larger of the two proteins of mature SLRSV capsids (L, 44kDa) had an ATG codon added at its 5 S/G site and a TAG stop codon sequence added at the 3-proximal S/G site. The P, L and S proteins were expressedin planta to a maximum concentration of 0.01 % of total extractable proteins but did not assemble into virus-like particles. When challenged by mechanical inoculation with virus particles or viral RNA, and compared with control plants, tobacco plants (primary transgenic clones or S1 and S2, kanamycin-resistant seedlings) expressing the virus capsid subunits separately, or their precursor, decreased the accumulation of SLRSV particles in inoculated leaves and fewer plants became invaded systemically. In experiments in which the roots of seedlings were exposed to SLRSV-carrying vector nematodes (Xiphinema diversicaudatum), SLRSV was detected in the roots of non-transformed control tobacco plants (6/20) and in transgenic tobacco expressing the L protein (7/40), but not in any of 25 tobacco plants expressing the S protein or in 35 expressing the P protein. This is the second example of CP-mediated resistance to virus inoculation by nematode vectors.     

Attachment and adhesion of conidia of Stagonospora nodorum to natural and artificial surfaces

Attachment and adhesion of conidia of a wheat-isolate of Stagonospora nodorum to leaf and artificial surfaces was studied. Attachment of conidia was a non-viable process, separate from adhesion, that occurred rapidly and irreversibly. Attachment involved conidial-surface carbohydrates and was partially influenced by surface hydrophobicity. The subsequent adhesion, via the secretion of extracellular matrix from conidia, was a viable process that induced the complete cover of conidia in response to wheat leaf surface components containing epi-cuticular wax and to a lesser extent to barley but inducing only partial covering on glass. Results suggest that specific surface components from the compatible host promote rapid attachment and adhesion of S. nodorum conidia.     

Cryopreservation of Ram Semen in Extenders Containing Soybean Lecithin as Cryoprotectant and Hyaluronic Acid as Antioxidant

A soybean lecithin‐based extender supplemented with hyaluronic acid (HA) was assayed for effectiveness to improve the quality of frozen–thawed ram semen. HA has not been tested yet in an extender containing soybean lecithin for freezing ram semen. Thus, the aim of this study was to analyse the effects of soybean lecithin at 1% or 1.5% along with HA at 0, 0.5 and 1 mg ml^‐1 in a Tris‐based extender on the motion characteristics, membrane integrity (HOST), viability, GSH peroxidase (GSH‐PX) activity, lipid peroxidation and acrosomal status after freezing–thawing. Semen was collected from four Mehraban rams during the breeding season and frozen in the six lecithin×HA extenders. The extender containing 1.5% lecithin supplemented with no HA yielded higher total motility (52.5%±1.6), viability (55.8%±1.6) and membrane integrity (44.5%±1.7), but the effects of the lecithin concentration did not reach signification. Linearity‐related parameters, ALH, BCF, lipid peroxidation, GSH‐PX activity, morphology and acrosomal status were not affected by the extender composition. In general, adding HA significantly decreased sperm velocity (1 mg ml^‐1 HA), total motility (only with 1.5% lecithin), viability (1 mg ml^‐1 HA for 1% lecithin; both concentrations for 1.5% lecithin) and membrane integrity. In conclusion, adding HA to the freezing extender supplemented with soybean lecithin failed to improve quality‐related variables in ram semen. Increasing the lecithin content could have a positive effect, but further studies are needed.     

Determination of Feeder Cell‐Based Cellular Niches Supporting the Colonization and Maintenance of Spermatogonial Stem Cells from Prepubertal Domestic Cat Testes

Recently, isolation and in vitro culture of putative spermatogonial stem cells (SSCs) in the domestic cat have been conducted. However, the cellular niche conditions that facilitate the establishment and long‐term maintenance of feline SSCs (FSSCs) have not been described. Therefore, we investigated the type of feeder cells used to stimulate colony formation and growth of FSSCs among the various factors in the FSSC niche. Spermatogonial stem cells isolated from feline testes were cultured on mitotically inactivated testicular stromal cells (TSCs) derived from cats, dogs and mice, and mouse embryonic fibroblasts (MEFs). The formation and growth of colonies derived from SSCs cultured on each type of feeder cell were identified at passage 0, and the morphology, alkaline phosphatase (AP) activity and expression of SSC‐specific genes in surviving colonies were investigated at passage 4. Among these diverse feeder cells, TSCs from cat showed the greatest colony formation, growth and maintenance of FSSCs, and SSC colonies cultured by passage 4 showed a typical dome‐shaped morphology, AP activity and expression of SSC‐specific genes (NANOG, OCT4, SOX2 and CD9). Accordingly, these results demonstrate that feline TSCs could be used as feeder cells to support the establishment and maintenance of SSCs from domestic cats.     

Superradiance in a torus magnetosphere around a black hole

The coalescence of a neutron star and a black hole in a binary system is believed to form a torus around a Kerr black hole. A similarly shaped magnetosphere then results from the remnant magnetic field of the neutron star. In the strong-field case, it contains a cavity for plasma waves located between the barrier of the gravitational potential and the surrounding torus. This cavity may be unstable to superradiance of electromagnetic waves. Superradiant amplification of such waves, initially excited by turbulence in the torus, should inflate into a bubble in a time as short as approximately 0.75 (1 percent/&cjs3539;epsilon&cjs3539;2)(M/7M middle dot in circle) seconds approximately 0.15 to 1.5 seconds, assuming an efficiency &cjs3539;epsilon&cjs3539;2 = 0.5 to 5 percent and a mass M = 7M middle dot in circle. These bubbles may burst and repeat, of possible relevance to intermittency in cosmological gamma-ray bursts. The model predicts gamma-ray bursts to be anticorrelated with their gravitational wave emissions.     

The influence of comb type on growth rate in the domestic fowl 1

Studies were made to determine the influence of comb type genes on growth rate. Three trials compared body weights of young birds while a fourth was concerned with embryonic weight at 13 days of incubation.

One of the trials on young birds included a comparison of thyroid and adrenal weights, shank length and breast angle. The majority of birds studied were heterozygous at any particular comb type locus. The following conclusions were based on results from these studies:

No consistent effects of comb type on mean body weight, thyroid weight, adrenal weight, shank length or breast angle were found. However, there were indications that comb type may affect the variances of these characters.

No significant weight differences were found among embryos of different comb types.     

Use of a potentiometric vital dye to determine the effect of the herbicide bromoxynil octanoate on mitochondrial bioenenergetics in Chlamydomonas reinhardtii

BACKGROUND: The aims of the present study were to validate a vital mitochondrial potentiometric staining method in Chlamydomonas reinhardtii and to utilise this method to examine the effect of the herbicide bromoxynil octanoate on mitochondrial potential in this species. A range of stains was investigated, including Rhodamine 123, DASPMI, Mitotracker Green, Mitotracker Orange and JC‐1. RESULTS: Rhodamine 123 (R123) had the highest utility of several candidate stains. Incubation with both 5 and 10 µM carbonyl cyanide 3‐chlorophenylhydrazone caused significant fluorescence collapse [Dunn's post test (40.00, P < 0.01) and (45.49, P < 0.01) respectively], demonstrating that the R123 fluorescence reported mitochondrial potential. The effect of the herbicide bromoxynil octanoate was examined. Exposure to 0.1 mM of bromoxynil resulted in a significant increased mitochondrial fluorescence compared with the baseline (Mann–Whitney U = 222, P < 0.002), while concentrations of 1 mM and greater resulted in significant, almost complete loss of mitochondrial potential [mean fluorescence ratio = 1.193–1.289 (where a ratio of 1 represents total potential loss), Mann–Whitney U = 0.0, P < 0.001 (1 mM ), 0.0, P < 0.0001 (2 mM ), 0.0, P < 0.0001 (5 mM )]. EC₅₀ of the collapse in mitochondrial potential owing to bromoxynil incubation occurred at 0.72 mM , and the mean t₅₀ of bromoxynil octanoate action was 93 s. CONCLUSIONS: R123 is a sensitive potentiometric dye in C. reinhardtii that may find further use in investigations of both mitochondrial bioenergetics in plants and environmental toxicology. Copyright © 2011 Society of Chemical Industry     

Species-dependent effects of border cell and root tip exudates on nematode behavior

ABSTRACT Effects of border cell and root tip exudates on root knot nematode (Meloidogyne incognita) behavior were examined. In whole-plant assays using pea, M. incognita second-stage juveniles (J2) accumulated rapidly around the 1- to 2-mm apical region ensheathed by border cells, but not in the region of elongation. Within 15 to 30 min, J2 which had accumulated within detached clumps of border cells lost motility and entered into a quiescent state. When border cells (and associated root tip exudates) were washed from pea roots prior to challenge with nematodes, no such accumulation and quiescence was induced. Attraction of nematodes by roots was species dependent: no attraction or accumulation occurred in snap bean. Using a quantitative assay, three categories of chemotaxis responses occurred: attraction (pea and alfalfa cv. Thor), repulsion (alfalfa cv. Moapa 69), and no response (snap bean and alfalfa cv. Lahonton). In contrast, total root tip exudates from all three plant species acted as a repellent for M. incognita in the sand assay. An in vitro assay was developed to characterize the induced quiescence response. When total root tip exudate from the tested legumes (as well as corn) was incubated with J2 populations, >80% of the nematodes lost motility. A similar response occurred in Caenorhabditis elegans. Border cell exudates did not induce or contribute to the induction of quiescence. Cocultivation of pea border cells with M. incognita resulted in changes in border cell shape similar to those observed in response to exogenous plant hormones. No such changes occurred in snap bean border cells. Understanding the cell- and host-specific extracellular recognition that occurs between roots and pathogenic nematodes in the early stages before infection occurs could lead to new avenues for disease control.     

The Adverse Effect of Phytoestrogens on the Synthesis and Secretion of Ovarian Oxytocin in Cattle

The current investigations were undertaken to study the mechanism of the adverse effect of phytoestrogens on the function of bovine granulosa (follicles >1< cm in diameter) and luteal cells from day 1–5, 6–10, 11–15, 16–19 of the oestrous cycle. The cells were incubated with genistein, daidzein or coumestrol (each at the dose of 1 × 10^?6 m ). The viability and secretion of estradiol (E2), progesterone (P4) and oxytocin (OT) were measured after 72 h of incubation. Moreover, the expression of mRNA for neurophysin‐I/OT (NP‐I/OT; precursor of OT) and peptidyl‐glycine‐α‐amidating monooxygenase (PGA, an enzyme responsible for post‐translational OT synthesis) was determined after 8 h of treatment. None of the phytoestrogens used affected the viability of cells except for coumestrol. The increased secretion of E2 and P4 was only obtained by coumestrol (p < 0.05) from granulosa cells from follicles <1 cm in diameter and decreased from luteal cells on days 11–15 of the oestrous cycle, respectively. All three phytoestrogens stimulated (p < 0.05) OT secretion from granulosa and luteal cells in all stages of the oestrous cycle and the expression of NP‐I/OT mRNA in the both types of cells. The expression of mRNA for PGA was stimulated (p < 0.05) by daidzein and coumestrol in granulosa cells, and by genistein and coumestrol in luteal cells. In conclusion, our results demonstrate that these phytoestrogens can impair the ovary function in cattle by adversely affecting the synthesis of OT in follicles and in corpus luteum. However, their influence on the ovarian steroids secretion was less evident.