Comparative studies of jaw morphology and ontogeny in two species of asexually reproducing Dorvilleidae (Annelida)

The jaw ontogeny of Dorvillea albomaculata and D. bermudensis was studied in cultured specimens, reproducing asexually by transverse fission. Mandibular growth was found to occur by lateral apposition. Maxillary development exhibited a gradual growth pattern, as opposed to the maxillary moults found in closely related species (Macnaughton et al. 2009). Details of dentition and numbers of maxillary plates as well as the ontogenetic growth patterns of the jaws were found to provide significant information of systematic value. Based on detailed studies of jaw ontogeny and morphology, Dorvillea albomaculata and D. bermudensis are here reassigned to the genus Parougia (Dorvilleidae, Annelida). This is supported by the external morphology as well as previous molecular studies.     

A precursor to hemoglobin mRNA in nuclei of immature duck red blood cells

A method is described for sedimenting RNA on a preparative scale in the presence of 85% formamide. It is likely that the RNA is fully denatured, since under the same conditions ribosomal RNA develops full hyperchromicity, and formaldehyde-treated and untreated ribosomal and nuclear RNA sediment in an identical manner.RNA from immature duck red blood cells was fractionated on sucrose gradients. The amount of hemoglobin mRNA and poly(A) in each fraction was measured by hybridization with complementary DNA and poly(U), respectively. We observed that hemoglobin mRNA forms aggregates in the presence of phenol, which are dispersed on formamide gradients. Nuclear RNA became more heavily aggregated, and again the aggregates were dispersed by formamide. A possible nuclear precursor of hemoglobin mRNA was identified. The molecular weight of the precursor is 6–7 × 10⁵, three times as long as hemoglobin mRNA, and it is attached covalently to a poly(A) sequence.     

Perinatal deaths: analysis by clinical cause to assess value of induction of labour.

Over the 10 years 1966-75 the rate of induction of labour in the Glasgow Royal Maternity Hospital has increased from 16-3% of all births. During the same period perinatal mortality fell from 33 to 22 per 1000, mainly because of significantly fewer deaths due to antepartum haemorrhage; trauma; maternal diseases; and unknown causes in mature babies. The reduction in the number of deaths of unknown causes in mature fetuses was achieved by preventing deaths occurring after 40 weeks and was recorded in all age and parity groups. The results suggested that increased use of induction of labour has contributed to the improved perinatal mortality rate.