SEXUAL ISOLATION BETWEEN A EUROPEAN AND AN AMERICAN POPULATION OF ECTOCARPUS SILICULOSUS (PHAEOPHYTA)1

Sexual plants of Northeastern American Ectocarpus siliculosus (Dilhw.) Lyngb. have been isolated and cultured. Female gametes produce a volatile sex hormone acting on male gametes. Combination of American and European gametes shows that the initial step of the sexual reaction (attraction of male gametes) works normally, whereas interaction of cell surfaces and fusion of gametes is prevented.     

Synthesizing double haploid hexaploid wheat populations based on a spontaneous alloploidization process

Doubled haploid(DH) populations are useful to scientists and breeders in both crop improvement and basic research.Current methods of producing DHs usually need in vitro culture for extracting haploids and chemical treatment for chromosome doubling.This report describes a simple method for synthesizing DHs(SynDH) especially for allopolyploid species by utilizing meiotic restitution genes.The method involves three steps:hybridization to induce recombination,interspecific hybridization to extract haploids,a...     

Inhibition of Ectocarpus siliculosus infestations with copper chloride in tank cultures of Gracilaria gracilis

This study investigated copper chloride as an inhibitor of infestations of Ectocarpus siliculosus in Gracilariagracilis (Stackhouse) Steentoft, Irvine and Farnham grown in outdoor tank cultures. Copper at concentrations of 400 and 800 μg L^-1 Cu²⁺ inhibited E. siliculosusin one experiment. A reduction in the specific growth rates of G. gracilis was found for both concentrations of copper chloride in two experiments. G. gracilis recovered completely with in three weeks in one experiment, while no recovery was found in the other. Three and 5 weeks after treatment with low and high concentrations of copper chloride respectively the specific growth rates of G. gracilis was higher than that of the control in one experiment. A feeding experiment was conducted to determine the effect of copper-treated G. gracilis, used as fodder, on the growth rates of Haliotes midae (abalone) of two size classes. An isolated occurrence of growth rate inhibition of H. midae could be demonstrated in both size classes 3 months after the startof the experiment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Gametes as embodied capital: perceptions on self-pricing reproductive biocommodities

The exchange of gametes has polarized and captivated the attention of biomedical practitioners, policy stakeholders, ethicists, and the general public alike. Studies have thoroughly explored the unique histories of this industry, its economies, legal statutes that influence clinical practice, motivating factors of donors, as well as debates on differentiating donor, offspring, and family rights from each other. This mixed-method study refocuses the analytical lens to examine the perceptions and decision-making processes of individual willingness to participate in gamete exchange networks in the United States for procreative or research purposes. Analyses revealed that individuals engage in a form of self-biocommodification, where ascribed values of gametes are explained as embodied capital and rationalized by Western biomedical explanatory models of genetics and reproduction. This work contributes to social scientific explanations of biocommodification while providing new points of departure in reconceptualizing science and technology studies through the perspectives of potential actors in gamete exchange networks.     

IMMUNOLOCALIZATION OF CENTER IN THE FLAGELLAR APPARATUS OF MALE GAMETES OF ECTOCARPUS SILICULOSUS (PHAEOPHYCEAE) AND OTHER BROWN ALGAL MOTILE CELLS1

Centrin or a centrin homologue was localized using immunofluorescence in the flagellar basal body region in zoids of five brown algal species: Ectocarpus siliculosus (Dillw.) Lyngb., Scytosiphon lomentaria (Lyngb.) Link, Laminaria digitata (Huds.) Lamour., Sphacelaria rigidula (Kütz.) Prud'homme van Reine, and Fucus serratus L. The antigen is restricted to short rods extending along the basal body(ies) and towards the nucleus, which always remains firmly linked to the flagellar apparatus in isolated cytoskeletons. To identify these antigenic sites, pre- and postembedding immunogold electron microscopy was applied to male gametes of E. siliculosus. At least three different structures associated with the basal bodies were antigenic: a fibrous structure connecting the proximal end of the posterior basal body to the nucleus (nucleus-basal body connector), a striated band that links the two basal bodies to each other and is located in the angel formed by them, and amorphous material interconnecting the basal bodies in their most proximal regions. In addiction, specific labeling occurs along the external surface and within the lumen of both basal bodies and in the flagellar transitional region. The possible function of these centrin-containing structures is discussed.     

In vitro gametogenesis: The end of egg donation?

This paper explores whether egg donation could still be ethically justified if in vitro gametogenesis (IVG) became reliable and safe. In order to do this, issues and concerns that might inform a patient’s reasoning in choosing to use donor eggs instead of IVG are explored and assessed. It is concluded that egg donation would only be ethically justified in a narrow range of special cases given the (hypothetical) availability of IVG treatment and, further, that egg donation could itself be replaced by donation through IVG techniques. Two possible criticisms of this position are then considered: Ones based on respect for patient wishes, and on loss of donor benefit. It is concluded that whilst neither argument constitutes a strong enough reason to continue with programmes of egg donation, egg‐sharing programmes could still be permitted come the advent of IVG; these could then provide a morally acceptable source of “natural” donor eggs.     

New members of a group of DNA viruses infecting brown algae

Since 1990 virus infections have been described in six brown algal species of the genera Ectocarpus, Feldmannia, Hincksia and Myriotrichia. These pathogens can be experimentally transmitted to healthy isolates of their hosts. A synopsis including new molecular and biochemical data shows that these viruses share common characteristics: genomes of double-stranded DNA, infection mode, morphology, extended temperence, and narrow host-specificity. These properties distinguish the brown algal viruses from all other known plant viruses.     

Occurrence of unreduced pollen in diploid blueberry species,Vaccinium sect. Cyanococcus

Summary A total of 1475 individuals belonging to 43 natural populations of seven diploid (2x) blueberry species (Vaccinium section Cyanococcus) and two natural interspecific 2x hybrid populations were evaluated for unreduced pollen production. Significant differences were found in the frequency of unreduced pollen producers between species and within and between populations of the same species. Individuals with 1% or more unreduced pollen were considered unreduced pollen producers. The average frequency of unreduced pollen producers in these diploid species was 13.5%, ranging from 7.4% (V. corymbosum) to 18.4% (V. darrowii). The frequency of unreduced pollen grains in individual clones varied from <-1% to 28.6%. The production of unreduced pollen was not associated with male fertility. The widespread occurrence of unreduced pollen in the diploid species should allow the introgression of this germ plasm to the tetraploid level via unilateral sexual polyploidization.New Jersey Agricultural Experiment Station, Publication No. D-12163-18-91, supported by State and U.S. Federal funds, USDA-ARS Specific Cooperative Agreement No. 58-3615-9-068     

Who gets the gametes? An argument for a points system for fertility patients

This paper argues that the convention of allocating donated gametes on a ‘first come, first served’ basis should be replaced with an allocation system that takes into account more morally relevant criteria than waiting time. This conclusion was developed using an empirical bioethics methodology, which involved a study of the views of 18 staff members from seven U.K. fertility clinics, and 20 academics, policy‐makers, representatives of patient groups, and other relevant professionals, on the allocation of donated sperm and eggs. Against these views, we consider some nuanced ways of including criteria in a points allocation system. We argue that such a system is more ethically robust than ‘first come, first served’, but we acknowledge that our results suggest that a points system will meet with resistance from those working in the field. We conclude that criteria such as a patient's age, potentially damaging substance use, and parental status should be used to allocate points and determine which patients receive treatment and in what order. These and other factors should be applied according to how they bear on considerations like child welfare, patient welfare, and the effectiveness of the proposed treatment.