Search Results

You are looking at 1 - 10 of 15 items for

  • Author: T. K. ROBERTS x
Clear All Modify Search
Free access

T. K. ROBERTS and B. BOETTCHER

Summary.

SCA has been identified as an iron-binding protein present in seminal plasma. It has an electrophoretic mobility similar to transferrin, and different from lactoferrin, whereas it shares immunological characteristics with lactoferrin not possessed by transferrin. The name scaferrin is proposed for this compound.

Free access

T. K. ROBERTS and J. C. BOURSNELL

A.R.C. Unit of Reproductive Physiology and Biochemistry,Cambridge

(Received 7th June 1974)

Previous publications (Boursnell & Roberts, 1974; Roberts, Boursnell & Brown, 1974; Roberts, Boursnell, Winsor & Mustill, 1974) have shown that the basic boar seminal haemagglutinin (Boursnell & Briggs, 1969) almost certainly combines with zinc in the seminal plasma (Boursnell, Baronos, Briggs & Butler, 1972) to produce reversible opalescence on cooling. The relative magnitude of the opalescence at any one temperature resembles the degree of damage observed when the spermatozoa are subjected to cold shock at that temperature. Boar spermatozoa also showed enhanced absorption of zinc protein at 4°C. Attempts were made to define the nature of the structures binding haemagglutinin. Nelson & Boursnell (1966) showed that substances of high molecular weight inhibited the haemagglutinin reaction, perhaps non-specifically, and no markedly inhibitory low molecular weight material could be found. Certain red cell species-specificities were, however, noted in some haemagglutinin fractions

Free access

WENDY J. BUTLER and T. K. ROBERTS

A.R.C Unit of Reproductive Physiology and Biochemistry, 307 Huntingdon Road, Cambridge CB3 0JQ

(Received 9th October 1974)

Rapid cooling of the spermatozoa of most mammalian species leads to irreversible decrease in motility and metabolism (Milovanov, 1934; Chang & Walton, 1940), leakage of intracellular proteins and enzymes (Mann & Lutwak-Mann, 1955), increase in the proportion of differentially stained cells (Easley, Mayer & Bogart, 1942) and changes in cellular cation concentrations (Blackshaw & Salisbury, 1957). These effects could all result from changes in permeability which suggests that the cell membrane is the principal target of injury. The visible disruption of membranes, particularly in the acrosomal region (Hancock, 1952), supports this hypothesis. Phospholipids are of major importance in membrane structure and ram, bull and boar spermatozoa are known to release phospholipid into the surrounding medium on cold shock and freezing (Darin-Bennett, Poulos & White, 1973).

Various compounds, most notably milk and egg yolk,

Free access

J. C. BOURSNELL and T. K. ROBERTS

Summary.

Zinc alone of the metals present in boar seminal plasma causes an opalescence in normal samples at room temperature. This opalescence is increased by cooling to 4° C, leading in some cases to a definite precipitate which redisperses on warming.

The normal opalescence can be minimized by addition of fractional millimolar amounts of EDTA equivalent to the zinc present. This treatment also abolishes the precipitate which occurs on cooling.

Free access

T. K. ROBERTS and J. C. BOURSNELL

Summary.

Lactoferrin isolated from sow milk (about 0·6 mg/ml) was shown to be chromatographically homogeneous, an observation supported by electrophoresis and by reaction against monospecific anti-lactoferrin antiserum. Isoelectric focusing showed multiple forms of the protein (i.e.p., 9·3 to 10·0) converted by neuraminidase to one form (i.e.p., 9·65). Boar seminal plasma contains immunologically identical lactoferrin (0·1 to 0·5 mg/ml) which binds strongly to boar spermatozoa.

Free access

T. K. ROBERTS, J. C. BOURSNELL and A. D. BROWN

Summary.

Opalescence and precipitation of boar seminal plasma proteins, specifically promoted by zinc, have been shown to be due to a zinc-precipitable protein (ZPP). The properties of this purified protein cannot be distinguished from those of the seminal haemagglutinin and their identity is postulated. The response of seminal plasma opalescence to low temperature is especially marked between 14°C and 6°C. This is notably similar to the already recorded response of sperm survival to cooling. When semen is cooled to 4°C, ZPP, accompanied by zinc, is absorbed by spermatozoa.

Free access

B. G. Dorsman, A. G. Tumboh-Oeri and T. K. Roberts

Summary. A modification of the leucocyte adherence-inhibition test was developed to study cell-mediated immunity to spermatozoa. The test is highly reproducible and requires very low numbers of leucocytes. Deposition of spermatozoa in the genital tract of the female mouse by one normal mating is sufficient to sensitize the female to sperm antigens and the degree of sensitization is independent of the number of matings and the strain of male, and is not enhanced by subsequent pregnancy.

Free access

K. S. P. BHUSHANA RAO, T. K. ROBERTS, P. L. MASSON and J. F. HEREMANS

In 1939, Sorensen & Sorensen discovered a red protein in bovine milk. This component, now usually called lactoferrin, is a glycoprotein with a γ-electrophoretic mobility, and consists of a single polypeptide chain with a molecular weight of 77,000. Like serum transferrin, it binds two ferric ions, but it differs in its amino acid composition, immunological properties and in the higher stability of its iron-complex at acid pH. These features apply to bovine as well as to human lactoferrin (Groves, 1960; Johansson, 1960; Montreuil, Tonnelat & Mullet, 1960; Blanc & Isliker, 1961; Masson & Heremans, 1968; Castellino, Fish & Mann, 1970; Querinjean, Masson & Heremans, 1971).

In the human, lactoferrin is not only found in milk but also occurs in other external secretions. It is synthesized by three types of tissues: the acini

Free access

T. K. ROBERTS, J. C. BOURSNELL, S. E. WINSOR and E. A. MUSTILL

Summary.

The temperature-dependent opalescence caused by the presence of a zinc-precipitable protein (ZPP) in boar seminal plasma has been shown to be pH-dependent.

The considerable pH increase to which boar seminal plasma is subject on exposure to air is attributed to loss of CO2 from a system with a notable paucity of titratable groups in the physiological range pH 7 to 9. This markedly affects the temperature-dependent opalescence.

The ZPP has been purified and the temperature-dependent opalescence of this material can be demonstrated only within a narrow range of zinc concentration in the absence of other possible ligands present in whole seminal plasma.

Free access

K. J. McDowell, D. C. Sharp, A. T. Fazleabas and R. M. Roberts

Summary. Conceptuses were obtained from pony mares on each day of pregnancy between Days 12 and 28, and on Days 39, 45, 65 and 100. Endometrium was obtained from mares at Days 12, 14, 16, 18, 39, 45, 65 and 100 of pregnancy, and from non-pregnant mares during anoestrus, during transition into the breeding season, at oestrus, or during dioestrus. Tissues were incubated in vitro for 24 h with l-[3H]leucine. Proteins synthesized and released into the culture medium were analysed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and fluorography.

Conceptuses obtained before Day 14 after ovulation released a characteristic pattern of labelled proteins. These included two groups of apparent isoelectric variants of relative molecular weights (M r) 30 000–40 000 (pI values 4·5–5·5 and 6–7), one group of M r ∼22 000 (pI 6·5–7), and large protein(s) that did not enter the 10% polyacrylamide gel. After Day 14 the array of labelled proteins had changed and resembled that produced by isolated yolk sac at the later stages of pregnancy studied. Included amongst these were several acidic polypeptides with M r 20 000 (pI 5–6).

The endometrial samples released an array of non-dialysable polypeptides into the culture medium. Fluorograms could be assigned to one of three general groups, with endometrium from mares within each group producing similar patterns of labelled proteins. The first group consisted of anoestrous, transitional and ovariectomized mares, and mares at oestrus or Day 1 or Day 18 after ovulation. The second group was comprised of mares at Days 12–16 of dioestrus or Days 12–18 of pregnancy. Mares from Day 39 through 100 of pregnancy made up the third group.

Keywords: embryo; horse; proteins; endometrium; electrophoresis