Genetics and Molecular Biology of Mouse Pigmentation

The formation of mouse coat color is a relatively complex developmental process that is affected by a large number of mutations, both naturally occurring and induced. The cloning of the genes in which these mutations occur and the elucidation of the mechanisms by which these mutations disrupt the normal pigmentation pattern is leading to an understanding of the way interactions between gene products lead to a final phenotype.     

The relation between protein synthesis and lipide accumulation in L strain cells and Ehrlich ascites cells

It has long been known that fat accumulates in old injured cells both in tissue culture and in many mammalian disease states. The use of L cells grown in suspension tissue culture permitted the opportunity to study conditions in which lipide accumulation could be retarded or accelerated. These cultures exhibit a three-phase growth curve which is similar to that previously found with bacteria and consists of a lag period, logarithmic growth period, and stationary period. Daily aliquots were removed from cultures going through these phases and protein and cholesterol content correlated with cell division. It was found that L cells gradually accumulated lipide in the cell concurrent with retardation of cell division and protein synthesis. Conversely old lipide-laden cells, placed in fresh media and encouraged to active division with net protein synthesis progressed from a high to a low lipide/cell ratio over a period of 2 to 4 days. An amino acid analogue p-fluorophenylalanine and a mitotic inhibitor, colchicine, also markedly increased the lipide/cell ratio. Similar results were found in in vitro experiments with Ehrlich ascites cells.     

A Comparison of Minerals Modified Glutamate Medium with Other Media for the Enumeration of Coliforms in Delicatessen Foods

A comparative assessment has been made of the performance of minerals modified glutamate medium (MMGM), lauryl sulphate tryptose broth (LST), MacConkey broth (MAC) and brilliant green bile broth (BGBB) in the enumeration of coliform organisms present in soft cheese, cooked meat and pâté. The medium MMGM was superior in sensitivity to the other three media and compared favourably with them in specificity; BGBB was inferior to the other media tested.     

An Ultrastructural Investigation of 180°-Rotated Ciliary Meridians in Tetrahymena pyriformis*

SYNOPSIS. An ultrastructural investigation has been carried out on 180°-rotated ciliary meridians (inverted meridians) in Tetrahymena pyriformis temperature-sensitive mutant (mol^b/mol^b), syngen 1, strain B. The longitudinal, transverse and postciliary microtubular bands, the kinetodesmal fiber, and the parasomal sac, are shown to be disposed at a 180° angle to their normal positions or orientations. Other abnormalities are as folows: the first 2 basal bodies of the inverted meridian fail to organize into “couplets” and the inverted meridian intrudes into the anterior pole region; an extra longitudinal microtubular band is found in one of the cell lines.     

Floristic composition and structure of a rainforest area 25yr after logging

In 1949 an area of undisturbed warm temperate rainforest (simple notophyll vine forest) in mid-north coastal New South Wales, Australia was studied in terms of both floristics and structure (Burges A. & Johnston R. D. J. Ecol. 41, 72-83, 1953). During 1955-56, the area in which the transect was located was logged. Over 90% of the upper closed canopy trees adjacent to the creek and on the lower slope and about 35% of canopy trees on the upper slope were removed. The area was reassessed in terms of floristics and structure in 1981. The greatest impact of logging in the study area was structural and largely confined to the flat adjacent to the creek and to the lower slope. With the exception of the remaining gaps covering 6% of the area, structural recovery time is estimated at 140-190 yr. In the gaps structural recovery may take up to 250 yr. All flowering plants, ferns and mosses previously recorded were present 25 yr after logging. The two alien plant species on the site are short lived intolerant species and gradually disappearing with canopy closure of the regenerating forest. The regeneration of the original tree species is healthy and vigorous with most regeneration resulting from the growth of advance regeneration present at the time of logging or the germination of new seedlings. Eleven per cent of the regeneration is attributable to coppicing. The importance of remnant canopy trees as a source of propagules for the trees and epiphytes is recognised. The larger openings are slower to recover as a result of lack of protection from frost. The stability of floristic composition of this area of warm temperate rainforest following heavy logging is demonstrated.