Search

Concentrations of insulin-like growth factor-I (IGF-I) were measured in granulosa and thecal tissue dissected from the three largest follicles in the ovaries of laying hens. The higher concentration was found in extracts of granulosa (0.82 ± 0.01 pmol/g wet wt) and theca (0.36 ± 0.02), both of which were greater than that in liver extracts (0.25 ± 0.01). RNA was extracted from these tissues, and by using reverse transcription and the polymerase chain reaction with primers specific for chicken IGF-I, both granulosa and thecal tissue were shown to express chicken IGF-I mRNA. Granulosa and thecal cell cultures were established and used to measure IGF binding sites and the response to exogenous IGF peptides in terms of DNA synthesis. Both cell types bound [¹²⁵I]IGF-I, which was displaced by IGF-I, IGF-II, and insulin in descending order of potency, characteristic of a type-I IGF receptor. Treatment of granulosa and thecal cell cultures with IGF-I resulted in a dose-dependent increase in [³H]thymidine incorporation into DNA by both cell types. LH, but not FSH, stimulated DNA synthesis in cultured granulosa cells but not in cultured thecal cells. This effect was enhanced in granulosa cells by the addition of IGF-I to the culture medium. These data are consistent with an autocrine or paracrine role for IGF-I within the developing ovarian follicle of the domestic hen. Copyright 1994, 1999 Academic Press

In the U.K. industrial wastes are often disposed by mixing with domestic refuse in landfill sites. The U.K. is almost unique in this respect and its disposal methods are coming under increasing environmental pressure at both a national and international level. This paper reviews the results of a major research programme to look at the behaviour of heavy metals and other contaminants in landfill sites. Work has included laboratory investigations and field studies at co-disposal sites in the U.K. and assesses the fate of heavy metals through an examination of their availability, binding processes, speciation and accumulation in vegetation and food chains. Whilst each metal is individual in character, results show that co-disposal, if properly carried out, is not as unsound environmentally as commonly portrayed.

A few words of explanation are required to enable those not familiar with the Carnarvon district fully to appreciate the importance of Prof. Bonney's confirmation of the view respecting the age of the Twt Hill conglomerate first put forward by Prof. Hughes, and afterwards advocated by myself. The controversy possesses a general interest, apart from the fact that the stratigraphical position of a certain bed is now fixed, inasmuch as it shows how cautious it is needful to be in dealing with these ancient rocks without the most thorough and careful mapping of the whole area.

A discussion has more than once arisen, in the course of the last two years, respecting the true position or the quartz conglomerate exposed near Twt Hill, Carnarvon, which was first described by Prof. Bonney and Mr. Houghton in the Quarterly Journal of the Geological Society, vol. xxxv. p. 321. The typical quarry is situated on the S.E. side of the ridge, close underneath Twt Hill, and the exposure there shows the quartz conglomerate in juxtaposition to the granitoid rock that constitutes the axis of the ridge. The authors describe a passage between the granitoidite below and the conglomerate above, and state that the latter ?passes lip into a rock which has some resemblance to the bottom rock? (granitoidite). In the GEOL. MAG. for March, 1880, p. 118, Dr. Callaway writes: ?Messrs. Bonney and Houghton have detected at Twt Hill a passage between the granitoidite and a quartzose conglomerate with a S.E. dip. I have visited this section, and having examined the rock inch by inch, I can entirely confirm their identification.?