Identification of a male-specific (H-Y) antigen on the flagellar plasma membrane of ram epididymal spermatozoa

Summary H-Y (male-specific) antigen has been detected on the plasma membranes of both caput and caudal ram spermatozoa using both immunoperoxidase and immunofluorescence labelling techniques. In these spermatozoa the distribution of H-Y antigen appears to be confined to both the posterior region of the head and the mid-piece region of the flagellum. In addition, caput spermatozoa also exhibit intense immunoperoxidase staining of the cytoplasmic droplet which is situated on the flagellum at the base of the head. Western blot analyses of purified plasma membranes from the flagella of caudal spermatozoa have revealed the presence of a malespecific protein with an estimated molecular weight of 25,000–27,000.     

R-prime plasmids from Bradyrhizobium japonicum and Rhizobium fredii

The formation of R-prime plasmids was selected in crosses involving soybean microsymbionts with genomic Tn5 insertions and carrying plasmid pJB3JI (with one IS2) copy as donors and Escherichia coli HB101 as recipient. Whereas the parent plasmid was 60 kb, recombinant plasmids between 76 kb and 121 kb were obtained. Restriction and Southern analyses confirmed the mobilization of Tn5 on four R-primes from Bradyrhizobium japonicum I-110 and on an R-prime plasmid from Rhizobium fredii HH303. The largest R-prime plasmid was obtained from the rescue of two symbiotically defective R. fredii mutant strains that required adenosine.Non-standard abbreviation TDP transposon donor pool Scientific article number A-4728 and contribution number 7724 of the Maryland Agricultural Experiment Station     

The composition and zonation of a Fucus serratus community in strangford lough,co. down

The flora and fauna associated with the serrated wrack, Fucus serratus L., in Strangford Lough have been studied. Fucus plants were larger where they were most abundant and their distribution was determined largely by the availability of suitable substratum; however, plant size was reduced under turbulent conditions. The fauna contained 79 taxa, of which eleven were common: these comprised four polyzoans, two tunicates, two sponges, two hydroids and a serpulid. All except three were more abundant on plants with low silt loads in turbulent, weedy areas. All species except Electra pilosa (L.) tended to occur on the concave surfaces of the plant. Evidence of zonation in each species' distribution along the plants was obtained. Analysis of association coefficients for the commonest species suggested that there are two distinct species groupings within the community.