Ornithine decarboxylase induction and the cytoskeleton in normal and transformed cells

ODC induction by fresh medium added to stationary, medium-depleted, confluent cultures has been studied in transformed HeLa and CHO cells, and in normal human fibroblasts as an indicator of the resumption of cell multiplication. The transformed HeLa cell displays a more easily reversed G₁ block, a higher peak ODC level, and a shorter time period for achievement of the peak ODC value than does the normal fibroblast. Low concentrations of microtubule depolymerizing agents like colchicine suppress ODC induction almost completely in the normal fibroblast, but hardly at all in the HeLa or CHO cells. Both transformed cells occasionally reveal a superinduction of ODC at very low colchicine levels (10^?8-10^?7 M) and a more variable response to such agents than does the normal fibroblast. Higher concentrations of colchicine suppress ODC induction in all cells. Experiments with actinomycin D and cycloheximide indicate that the principal colchicine action involves inhibition at the level of protein or mRNA synthesis, rather than inactivation of the already synthesized enzyme. These experiments are provisionally interpreted as an indication that a microtubular system is needed to reinitiate certain steps associated with growth in G₁-blocked, normal cells, and that a second microtubular action terminating enzyme biosynthesis may exist. This microtubular control is defective in the transformed cells here studied. Specific microtubular actions necessary for initiation and termination of protein syntheses may occur throughout the cell reproductive cycle, and in the course of normal differentiation processes.     

A simple enzyme assay for dry matter digestibility and its value in studying food selection by generalist herbivores

Summary The dry matter digestibility of 94 species of leaf was assayed by a simple method involving sequential treatment with pepsin and fungal cellulase enzymes. It was demonstrated that for foliage from rainforest trees of a wide range of dicotyledonous plant families the assay showed high positive correlation with estimates of dry matter digestibility obtained using rumenliquor from a fistulated steer. Both assays were found to reflect negative correlates of digestibility, notably fibre and condensed tannin, rather than the nutritional value of an item. The higher dry matter digestibility of immature leaves relative to mature leaves appeared to be accounted for by their lower fibre content. It is suggested that the pepsin/cellulase assay offers a cheap, quick, routine method of gaining information on the effects of some types of plant secondary compounds (digestibility reducers) on the food potential of different kinds of foliage to herbivores. Its use in studies of herbivory in rainforest areas in relation to analyses for plant secondary compounds and food selection by herbivores is discussed.Publication 20-018 of the Wisconsin Regional Primate Research Center     

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.     

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.

     

Manganese (hyper)accumulation within Australian Denhamia (Celastraceae): an assessment of the trait and manganese accumulation under controlled conditions

Plant and Soil - The genus Denhamia(Celastraceae) includes fifteen Australian species, many of which have a propensity for manganese (Mn) (hyper)accumulation. Among the key aims of this study were...     

The Schistosome Oesophageal Gland: Initiator of Blood Processing

Background

Although the ultrastructure of the schistosome esophageal gland was described >35 years ago, its role in the processing of ingested blood has never been established. The current study was prompted by our identification of MEG-4.1 expression in the gland and the observation of erythrocyte uncoating in the posterior esophagus.

Methodology/Principal Findings

The salient feature of the posterior esophagus, characterized by confocal and electron microscopy, is the enormous increase in membrane surface area provided by the plate-like extensions and basal invaginations of the lining syncytium, with unique crystalloid vesicles releasing their contents between the plates. The feeding process was shown by video microscopy to be divided into two phases, blood first accumulating in the anterior lumen before passing as a bolus to the posterior. There it streamed around a plug of material revealed by confocal microscopy as tethered leucocytes. These were present in far larger numbers than predicted from the volume of the lumen, and in varying states of damage and destruction. Intact erythrocytes were detected in the anterior esophagus but not observed thereafter, implying that their lysis occurred rapidly as they enter the posterior. Two further genes, MEGs 4.2 and 14, were shown to be expressed exclusively in the esophageal gland. Bioinformatics predicted that MEGs 4.1 and 4.2 possessed a common hydrophobic region with a shared motif, while antibodies to SjMEG-4.1 showed it was bound to leucocytes in the esophageal lumen. It was also predicted that MEGs 4.1 and 14 were heavily O-glycosylated and this was confirmed for the former by 2D-electrophoresis and Western blotting.

Conclusions/Significance

The esophageal gland and its products play a central role in the processing of ingested blood. The binding of host antibodies in the esophageal lumen shows that some constituents are antibody targets and could provide a new source of vaccine candidates.