Polyadenylated RNA complementary to repetitive DNA in mouse L-cells.

Complementary DNA, synthesized with L-cell polyadenylated RNA as template, renatured with total L-cell DNA to about 70%. About 30% complementary to unique sequence DNA and another 10 and 30% corresponded to sequences about 20- and 500-fold repetitive. Complementary DNA was fractionated after partial hybridization with total polyadenylated RNA to obtain preparations enriched or impoverished in complements of the most frequent polyadenylated RNA. Renaturation of these complementary DNA fractions with L-cell DNA revealed that most frequent RNAs are transcribed from repetitive DNA sequences, Complementary DNA, density labeled with bromodeoxyuridine, was fractionated by renaturation with L-cell DNA to yield fractions enriched in repetitive and unique sequence DNA. The denisty labeled complementary DNA was purified by equilibrium centrifiguation in an alkaline Cs2SO4 gradient. The complementary DNA representing mainly repetitive DNA sequences hybridized preferentially to frequent polyadenylated RNA.     

The humoral response of mouse spleen cells to two types of sheep erythrocytes. III. A new VH region marker.

It was previously shown that there is multigene control of the response of mouse spleen cells to two types of sheep erythrocytes (H and L). Discriminator strains of mice make a much higher response to extra antigens found only on H SRBC than to the shared antigens found on both types of erythrocyte. Non-discriminator strains respond only to the shared antigens, making a response as great as the discriminator response to the extra antigens. In this study we have shown that the response to the extra antigen(s) on H SRBC is under the genetic control of a gene(s) located in the VH region near or to the left of the A5a, alpha 1, 3-dextran and NP makers.     

A study of oestrus and fecundity in a laboratory colony of Mouse opossums (Marmosa robinsoni)

Twenty wild caught Mouse opossums Marmosa robinsoni Bangs 1898 formed the basis of a laboratory colony which was maintained at the Brookfield Zoo during 1971–3. Approximately 250 young including 3rd-generation descendants were produced.
M. robinsoni is polyoestrous with a mean cycle length of 25.5±0.5 days. Vaginal oestrus, which normally lasts three days, is accompanied by a pronounced cycle of cornification and mucification. During this period large numbers of desquamated epithelial cells and mucus are found in the urine. Females are sexually receptive 24 hours before cornified cells first appear in the urine and receptivity lasts two to four days. Fertile copulation takes place throughout this period. Ovulation is spontaneous and occurs late in oestrus. The mean number of corpora lutea recorded was 19.8±0.9 ( n =23).
Anovular cycles, associated with atresia of mature Graafian follicles, were found in approximately 25% of the females. The sterile cycles, which had a mean length of 15.6±0.7 days, were not always accompanied by a behavioural oestrus. Observations on the behaviour of introduced pairs provided direct evidence of sexual incompatibility. Sexual incompatibility was found to have been responsible for at least 10% of the unsuccessful pairings recorded during the study.
There were no indications in the Brookfield colony of the decline in productivity among laboratory-bred animals reported in other Marmosa colonies. Litter-sizes and litter-rates in the F₁ and F₂ generations did not differ from those in the wild-caught generation. However, the fact that only one out of three pairings produced young suggests that productivity in the colony was lower than in the wild. The cause of this low productivity was not established.     

Complex phylogenetic distribution of a non-canonical genetic code in green algae

Background  

A non-canonical nuclear genetic code, in which TAG and TAA have been reassigned from stop codons to glutamine, has evolved independently in several eukaryotic lineages, including the ulvophycean green algal orders Dasycladales and Cladophorales. To study the phylogenetic distribution of the standard and non-canonical genetic codes, we generated sequence data of a representative set of ulvophycean green algae and used a robust green algal phylogeny to evaluate different evolutionary scenarios that may account for the origin of the non-canonical code.     

Using Effort to Measure Reward Value of Faces in Children with Autism

According to one influential account, face processing atypicalities in autism reflect reduced reward value of faces, which results in limited attention to faces during development and a consequent failure to acquire face expertise. Surprisingly, however, there is a paucity of work directly investigating the reward value of faces for individuals with autism and the evidence for diminished face rewards in this population remains equivocal. In the current study, we measured how hard children with autism would work to view faces, using an effortful key-press sequence, and whether they were sensitive to the differential reward value of attractive and unattractive faces. Contrary to expectations, cognitively able children with autism did not differ from typically developing children of similar age and ability in their willingness to work to view faces. Moreover, the effort expended was strongly positively correlated with facial attractiveness ratings in both groups of children. There was also no evidence of atypical reward values for other, less social categories (cars and inverted faces) in the children with autism. These results speak against the possibility that face recognition difficulties in autism are explained by atypical reward value of faces.     

Ponasterone A: a new ecdysteroid from the embryos and serum of brachyuran crustaceans

The apolar ecdysteroid present in the developing embryo of the blue crab, Callinectes sapidus Rathbun, is tentatively identified as ponasterone A (2 beta, 14 alpha, 20,22-pentahydroxy-5, beta-cholest-7-en-6-one) on the basis of chromatographic, immunological, and mass spectral evidence. The apolar ecdysteroid present in the serum of land crabs, Gecarcinus lateralis, in the late premolt stages of the intermolt cycle is also tentatively identified as ponasterone A on the basis of chromatographic and immunological evidence.     

Statistical optimisation of growth conditions and diesel degradation by the Antarctic bacterium,Rhodococcus sp. strain AQ5‒07

Petroleum pollution is a major concern in Antarctica due to the persistent nature of its hydrocarbon components coupled with the region’s extreme environmental conditions, which means that bioremediation approaches are largely inapplicable at present. The current study assessed the ability of the psychrotolerant phenol-degrader, Rhodococcus sp. strain AQ5-07, to assimilate diesel fuel as the sole carbon source. Factors expected to influence the efficiency of diesel degradation, including the initial hydrocarbon concentration, nitrogen source concentration and type, temperature, pH and salinity were studied. Strain AQ5-07 displayed optimal cell growth and biodegradation activity at 1% v/v initial diesel concentration, 1 g/L NH₄Cl concentration, pH 7 and 1% NaCl during one-factor-at-a-time (OFAT) analyses. Strain AQ5-07 was psychrotolerant based on its optimum growth temperature being near 20 °C. In conventionally optimised media, strain AQ5-07 showed total petroleum hydrocarbons (TPH) mineralisation of 75.83%. However, the optimised condition for TPH mineralisation predicted through statistical response surface methodology (RSM) enhanced the reduction to 90.39% within a 2 days incubation. Our preliminary data support strain AQ5-07 being a potential candidate for real-field soil bioremediation by specifically adopting sludge-phase bioreactor system in chronically cold environments such as Antarctica. The study also confirmed the utility of RSM in medium optimisation.