Expression of uncoupling protein-3 subsarcolemmal and intermyofibrillar mitochondria of various mouse muscle types and its moduclation by fasting

Uncoupling protein-3 (UCP3) is a mitochondrial inner-membrane protein abundantly expressed in rodent and human skeletal muscle which may be involved in energy dissipation. Many studies have been performed on the metabolic regulation of UCP3 mRNA level, but little is known about UCP3 expression at the protein level. Two populations of mitochondria have been described in skeletal muscle, subsarcolemmal (SS) and intermyofibrillar (IMF), which differ in their intracellular localization and possibly also their metabolic role. To examine if UCP3 is differentially expressed in these two populations and in different mouse muscle types, we developed a new protocol for isolation of SS and IMF mitochondria and carefully validated a new UCP3 antibody. The data show that the density of UCP3 is higher in the mitochondria of glycolytic muscles (tibialis anterior and gastrocnemius) than in those of oxidative muscle (soleus). They also show that SS mitochondria contain more UCP3 per mg of protein than IMF mitochondria. Taken together, these results suggest that oxidative muscle and the mitochondria most closely associated with myofibrils are most efficient at producing ATP. We then determined the effect of a 24-h fast, which greatly increases UCP3 mRNA (16.4-fold) in muscle, on UCP3 protein expression in gastrocnemius mitochondria. We found that fasting moderately increases (1.5-fold) or does not change UCP3 protein in gastrocnemius SS or IMF mitochondria, respectively. These results show that modulation of UCP3 expression at the mRNA level does not necessarily result in similar changes at the protein level and indicate that UCP3 density in SS and IMF mitochondria can be differently affected by metabolic changes.

Expression of Na+/H+ exchanger mRNA in the gills of the Atlantic hagfish (Myxine glutinosa) in response to metabolic acidosis

Sodium/proton exchangers (NHE) are transmembrane proteins that facilitate the exchange of a Na⁺ ion for a H⁺ ion across cellular membranes. The NHE are present in the gills of fishes and are believed to function in acid-base regulation by driving the extrusion of protons across the branchial epithelium in exchange for Na⁺ in the water. In this study, we have used reverse transcriptase-polymerase chain reaction (RT-PCR) to detect the presence of a branchial NHE in the gills of the Atlantic hagfish, Myxine glutinosa. The subsequent partial cDNA sequence shares homology with other vertebrate and invertebrate NHE isoforms. In addition, using semi-quantitative, multiplex RT-PCR we demonstrate that mRNA expression of hagfish gill NHE is upregulated following an induced metabolic acidosis. Expression was increased to 4.4 times basal levels at 2-h post-infusion and had decreased to 1.6 times basal by 6 h. Expression had returned to basal levels by 24-h post-infusion. The inference from this study is that a gill NHE which is potentially important in acid-base regulation has been present in the vertebrate lineage since before the divergence of the hagfishes from the main vertebrate line.

Weaning of Australian shortfin glass eels (Anguilla Australis): a comparison on the effectiveness of four types of fish roe

Eel culture is solely dependent on wild seed stock, caught in estuaries during the freshwater migratory phase as glass eels. The methods used for weaning glass eels are very variable, and range from the use of live zooplankton to fish roe to fines of commercial fish feeds. The present experiments were conducted on glass eels of the Australian shortfin eel, when the effectiveness of four types of readily available fish roe (European carp, mirror dory, orange roughy and warehou) were evaluated over a 42-day period, in the laboratory.

After 28 days the eels did not show an interest in orange roughy and mirror dory roe, and these two treatments were discontinued to avoid mortality. In all treatments there was a decrease in mean weight during this period, but the survival was over 99%. In the 28th to 42nd day period the mean weight and specific growth rate of glass eels reared on European carp and warehou roe increased, but the differences between these two treatments were not significant.

The physical features of the roe and the oocytes thereof, the proximate composition, amino acid and fatty acid composition indicated major differences amongst the roe types, particularly with regard to the amount of n−6 polyunsaturated fatty acids (PUFA) and the ratio of n−3 to n−6. European carp and warehou roe (and oocytes) had a significantly higher arachidonic acid (AA-20:4n−6; over 60% of PUFA) content and a considerably lower n−3 to n−6 ratio (n−3 to n−6 ratio being 1.32, 5.92, 3.77 and 2.67 for roe types, and 1.25, 4.83, 2.91 and 2.42 for oocytes, of European carp, mirror dory, orange roughy and warehou, respectively), than in the other two roe types. The fatty acid profiles of European carp and warehou roe were similar to that of metamorphosing glass eels.

Lipid and fatty acid digestibility of three oil types in the Australian shortfin eel, Anguilla australis

The lipid and fatty acid digestibilities of three semi-purified, isonitrogenous (48.9–50.8% protein) and isocalorific (19.1–20.8 kJ g⁻¹) diets, in which the lipid source was either cod liver oil (CLO), linseed oil (LO) or sunflower oil (SFO), were estimated in the Australian shortfin eel (Anguilla australis) using chromic oxide as an external marker. Apparent percent protein and energy digestibilities of the diets were not significantly (P>0.05) affected by the lipid source, but the lipid digestibility was. The percent apparent lipid digestibility was lowest in the LO diet (90.2±0.6) and highest in the CLO diet (95.6±0.2).

Not all the fatty acids present in any one diet were recovered in the faecal samples. In diets with CLO, only three saturates (out of five), five monoenes and six (out of 11) PUFAs were detected in faecal samples. With all the diets, 20:0 and 22:0, and none of the n−6 HUFA were detected in the faecal samples. The digestibility of all the fatty acids, except 18:3n−3, was lowest in the diet with LO, and significantly so (P>0.05) from the other diets.

In shortfin eel, there was a trend for the digestibility of saturated fatty acids of diets with the animal oil as the lipid source to decrease with increasing chain length, and in diets with vegetable oil to increase initially and then decrease. A somewhat comparable trend was also evident in respect of monoenes.

When the digestibility of different categories of fatty acids is considered, the digestibility of saturates, monoenes, unsaturates, n−6, PUFA, HUFA and total fatty acid digestibilities of LO diet were the lowest, and differed significantly (P<0.05) from those of the CLO and SFO diets, except in the case of n−3 fatty acids.

Tanis: a link between type 2 diabetes and inflammation?

Here we describe a novel protein, which we have named Tanis, that is implicated in type 2 diabetes and inflammation. In Psammomys obesus, a unique polygenic animal model of type 2 diabetes and the metabolic syndrome, Tanis is expressed in the liver in inverse proportion to circulating glucose (P = 0.010) and insulin levels (P = 0.004) and in direct proportion with plasma triglyceride concentrations (P = 0.007). Hepatic Tanis gene expression was markedly increased (3.1-fold) after a 24-h fast in diabetic but not in nondiabetic P. obesus. In addition, glucose inhibited Tanis gene expression in cultured hepatocytes (P = 0.006) as well as in several other cell types (P = 0.001–0.011). Thus, Tanis seems to be regulated by glucose and is dysregulated in the diabetic state. Yeast-2 hybrid screening identified serum amyloid A (SAA), an acute-phase inflammatory response protein, as an interacting protein of Tanis, and this was confirmed by Biacore experiments. SAA and other acute-phase proteins have been the focus of recent attention as risk factors for cardiovascular disease, and we contend that Tanis and its interaction with SAA may provide a mechanistic link among type 2 diabetes, inflammation, and cardiovascular disease.

Dietary regulation of fat oxidative gene expression in different skeletal musle fiber types

Objective: To determine the effect of a high-fat diet on the expression of genes important for fat oxidation, the protein abundance of the transcription factors peroxisome proliferator-activated receptor (PPAR) isoforms α and γ, and selected enzyme activities in type I and II skeletal muscle. Research Methods and Procedures: Sprague-Dawley rats consumed either a high-fat (HF: 78% energy, n = 8) or high-carbohydrate (64% energy, n = 8) diet for 8 weeks while remaining sedentary. Results: The expression of genes important for fat oxidation tended to increase in both type I (soleus) and type II (extensor digitorum longus) fiber types after an HF dietary intervention. However, the expression of muscle type carnitine palmitoyltransferase I was not increased in extensor digitorum longus. Analysis of the gene expression of both peroxisome proliferator-activated receptor-γ coactivator and forkhead transcription factor O1 demonstrated no alteration in response to the HF diet. Similarly, PPARα and PPARγ protein levels were also not altered by the HF diet. Discussion: An HF diet increased the expression of an array of genes involved in lipid metabolism, with only subtle differences evident in the response within differing skeletal muscle fiber types. Despite changes in gene expression, there were no effects of diet on peroxisome proliferator-activated receptor-gamma coactivator and forkhead transcription factor O1 mRNA and the protein abundance of PPARα and PPARγ.

Consumers' health perceptions of three types of milk: a survey in Australia

A survey was conducted among 345 randomly selected shoppers in Melbourne, Australia, to identify their perceptions of the healthiness of whole milk, reduced fat milk and soy milk and to investigate demographic influences on health perceptions and types of milk consumption. The survey revealed major differences in shoppers' perceptions of the three types of milk along the themes of bone health, weight control, disease prevention, and, allergy and disease causation. Generally whole milk was perceived more negatively than soy or reduced fat milk. There were few demographic differences in the shoppers' perceptions of the three products. Reported consumption of reduced fat milk was more frequent among women and elderly people, and whole milk consumption was positively related to parenthood. The findings suggest that previous marketing and education campaigns have been effective but the widespread uncertainty and erroneous beliefs about milk products suggest that many consumers have not assimilated new findings about milk products. This represents a challenge for industry and public health practitioners.

Consumers` sensory and nutritional perceptions of three types of milk

Objective: To identify consumer perceptions of whole milk, reduced-fat milk and soy milk, and to investigate demographic influences on perceptions and types of milk consumption.

Design and setting: Questionnaires covering nutritional and sensory perceptions of three types of milk.

Subjects: Three hundred and sixty-one randomly selected shoppers in Melbourne, Australia.

Results: Generally, respondents held positive perceptions about milk. Milk was considered as having good sensory properties, providing a good source of nutrients, and being a convenient and safe product. However, despite these findings, misperceptions and unawareness about the nutrient content of milk were prevalent. Negative perceptions were most common for whole milk and were mostly related to its perceived high fat, cholesterol and energy contents. Soy milk received lower ratings on sensory quality and convenience than dairy milk. There were few sociodemographic differences in consumers' perceptions. Although reduced-fat milk consumption was more frequent among elderly people and type of milk consumption was related to parenthood, no other significant effects of demographic variables were found on the consumption of specific milk types.

Conclusion: Although positive perceptions were common, negative perceptions and misperceptions appear to be prevalent, presenting a challenge for nutrition education. Sociodemographic factors were not shown to be important predictors of perceptions and type of milk consumption.

Muscle glycogen and metabolic regulation

Muscle glycogen is an important fuel for contracting skeletal muscle during prolonged strenuous exercise, and glycogen depletion has been implicated in muscle fatigue. It is also apparent that glycogen availability can exert important effects on a range of metabolic and cellular processes. These processes include carbohydrate, fat and protein metabolism during exercise, post-exercise glycogen resynthesis, excitation–contraction coupling, insulin action and gene transcription. For example, low muscle glycogen is associated with reduced muscle glycogenolysis, increased glucose and NEFA uptake and protein degradation, accelerated glycogen resynthesis, impaired excitation–contraction coupling, enhanced insulin action and potentiation of the exercise-induced increases in transcription of metabolic genes. Future studies should identify the mechanisms underlying, and the functional importance of, the association between glycogen availability and these processes.

[P]lucky Jane et al: ideal types in the legal academy?

This article started as a response to a decision by Deakin University's Law School late last year to embark upon a major recruitment of new staff. That decision caused the writer to wonder what published sources of advice were available to assist aspiring legal academics in choosing and shaping a career. To date it would seem that whilst there is no dearth of sources about what law schools should teach, or on the content and structure of the curriculum, research on the selection and formation of academics is somewhat less common. This is changing. In 2003 a short biographical study of six law teachers, based on structured interviews, was published and in 2004, a major study of the identity of 54 law teachers became available. There have also been significant studies on the particular issues encountered by female academics in the legal academy.

The effect of intellectual disability on children's recall of an event across different question types

This research examined the performance of 80 children aged 9–12 years with either a mild and moderate intellectual disability when recalling an innocuous event that was staged in their school. The children actively participated in a 30-min magic show, which included 21 specific target items. The first interview (held 3 days after the magic show) provided false and true biasing information about these 21 items. The second interview (held the following day) was designed to elicit the children's recall of the target details using the least number of specific prompts possible. The children's performance was compared with that of 2 control groups; a group of mainstream children matched for mental age and a group of mainstream children matched for chronological age. Overall, this study showed that children with either a mild or moderate intellectual disability can provide accurate and highly specific event-related information. However, their recall is less complete and less clear in response to free-narrative prompts and less accurate in response to specific questions when compared to both the mainstream age-matched groups. The implications of the findings for legal professionals and researchers are discussed.