Satellite cell regulation of muscle mass is altered at old age.

Muscle mass is decreased with advancing age, likely due to altered regulation of muscle fiber size. This study was designed to investigate cellular mechanisms contributing to this process. Analysis of male Fischer 344 X Brown Norway rats at 6, 20, and 32 mo of age demonstrated that, even though significant atrophy had occurred in soleus muscle by old age, myofiber nuclear number did not change, resulting in a decreased myonuclear domain. Also, the number of centrally located nuclei was significantly elevated in soleus muscle of 32-mo-old rats, correlating with an increase in gene expression of MyoD and myogenin. Whereas total 5'-bromo-2'deoxyuridine (BrdU)-positive nuclei were decreased at older ages, BrdU-positive myofiber nuclei were increased. These results suggest that, with age, loss of muscle mass is accompanied by increased myofiber nuclear density that involves fusion of proliferative satellite cells, resembling ongoing regeneration. Interestingly, centrally located myofiber nuclei were not BrdU labeled. Rats were subjected to hindlimb suspension (HS) for 7 or 14 days and intermittent reloading during HS for 1 h each day (IR) to investigate how aging affects the response of soleus muscle to disuse and an atrophy-reducing intervention. After 14 days of HS, soleus muscle size was decreased to a similar extent at all three ages. However, myofiber nuclear number and the total number of BrdU-positive nuclei decreased with HS only in the young rats. IR was associated with an attenuation of atrophy in soleus muscles of 6- and 20- but not 32-mo-old rats. Furthermore, IR was associated with an increase in BrdU-positive myofiber nuclei only in young rats. These data indicate that altered satellite cell function with age contributes to the impaired response of soleus muscle to an intervention that attenuates muscle atrophy in young animals during imposed disuse.     

River Red Gum (Eucalyptus camaldulensis Dehnh.) organic matter as a carbon source in the lower Darling River,Australia

The Darling River, in New South Wales, Australia, is a large semi-arid system with a highly variable flow regime, characterised by unpredictable events of flooding and drought. In large lowland rivers like the Darling, lateral (river-floodplain) interactions can greatly influence both physical and biological components of the system. The floodplain and riparian zone of the Darling River is dominated by River Red Gum (RRG), Eucalyptus camaldulensis. The large amount of organic matter they produce accumulates on the floodplain and on benches within the channel, and is subject to alternate periods of flooding and drying as a result of highly variable flows. This paper examines the effect of alternate periods of flooding and drying on the processing of E. camaldulensis organic matter. Results of the 6-month in situ field study, together with results from laboratory experiments comparing dissolved organic carbon (DOC) release from various RRG litter types, suggest that RRG leaves provide the most bio-available source of carbon to the system, while bark may be more important as a habitat for invertebrates and other fauna. Laboratory experiments exploring the effect of drying and re-flooding on litter breakdown and release of DOC suggested that the majority of DOC was released from RRG leaves in the first 24 h of inundation. Also, upon drying and re-flooding of the leaves, a smaller but significant release of DOC occurred. However, an alternative wet/dry cycle did not affect weight loss of the leaf litter. Results of the field and lab experiments suggest that RRG leaves represent an important source of carbon to the Darling River, with inputs being influenced by the highly variable flow regime.     

Optimized somatic embryogenesis in Pinus strobus L.

Summary Somatic embryogenesis (SE) initiation in Pinus strobus was optimized by the manipulation of plant growth regulator (PGR) concentrations in the culture medium. Modified Litvay medium (MLV) of Litvay et al. (1985) supplemented with lower than routinely used PGR concentration increased initiation of established embryogenic cultures from approximately 20 to 53%. The original developmental stage of zygotic embryos had a pronounced effect on the SE response. The optimum stage was the pre- to shortly post-cleavage stage. A substantial genetic influence on initiation of SE was indicated by a significant variance component due to families. Genotype X collection date and genotype X media interactions had large effects on initiation of SE. The PGR levels in the culture medium prior to maturation had a significant effect on subsequent production of mature somatic embryos. Embryogenic tissue initiated and proliferated on medium with a low level of PGR consistently produced a high number of somatic embryos, indicating that optimized initiation protocol also enhanced somatic embryo production. Somatic embryos of 93 embryogenic lines (representing five families) that were initiated on media with different PGR concentrations were converted to plants at an overall frequency of 76%, and grown in the greenhouse. With these improved protocols, application of P. strobus SE in commercial clonal forestry is feasible as an alternative to traditional breeding and reforestation.     

Disruption of Rhino Demography by Poachers May Lead to Population Declines in Kruger National Park,South Africa

The onslaught on the World’s rhinoceroses continues despite numerous initiatives aimed at curbing it. When losses due to poaching exceed birth rates, declining rhino populations result. We used previously published estimates and growth rates for black rhinos (2008) and white rhinos (2010) together with known poaching trends at the time to predict population sizes and poaching rates in Kruger National Park, South Africa for 2013. Kruger is a stronghold for the south-eastern black rhino and southern white rhino. Counting rhinos on 878 blocks 3x3 km in size using helicopters, estimating availability bias and collating observer and detectability biases allowed estimates using the Jolly’s estimator. The exponential escalation in number of rhinos poached per day appears to have slowed. The black rhino estimate of 414 individuals (95% confidence interval: 343-487) was lower than the predicted 835 individuals (95% CI: 754-956). The white rhino estimate of 8,968 individuals (95% CI: 8,394-9,564) overlapped with the predicted 9,417 individuals (95% CI: 7,698-11,183). Density- and rainfall-dependent responses in birth- and death rates of white rhinos provide opportunities to offset anticipated poaching effects through removals of rhinos from high density areas to increase birth and survival rates. Biological management of rhinos, however, need complimentary management of the poaching threat as present poaching trends predict detectable declines in white rhino abundances by 2018. Strategic responses such as anti-poaching that protect supply from illegal harvesting, reducing demand, and increasing supply commonly require crime network disruption as a first step complimented by providing options for alternative economies in areas abutting protected areas.     

Stereospecific high-performance liquid chromatographic assay of ibuprofen: improved sensitivity and sample processing efficiency

A high-performance liquid chromatographic (HPLC) assay suitable for the analysis of the enantiomers of the non-steroidal anti-inflammatory drug ibuprofen (IB) in plasma was developed. Following the addition of racemic fenoprofen as internal standard (I.S.), samples are acidified and extracted with a mixture of isooctane—isopropanol (95:5, v/v). After evaporation of the organic layer, the drug and I.S. are derivatized with S-(−)-1(1-naphthyl)ethylamine (S-NEA) after addition of ethyl chloroformate as the coupling reagent. Ethanolamine is added 3 min after the addition of S-NEA to react with the excessive ethyl chloroformate. The resultant diastereomers corresponding to IB and I.S. were chromatographed at ambient temperature on a 100 mm × 4.6 mm I.D. C₁₈ reversed-phase column using acetonitrile—water—acetic acid—triethylamine (60:40:0.1:0.02) as the mobile phase pumped at a flow-rate of 1.2 ml/min. Detection of the fluorescent chromophore was at 280 and 320 nm for excitation and emission, respectively. The suitability of the assay for clinical pharmacokinetic studies of IB was determined by the analysis of plasma samples obtained from a healthy volunteer, following administration of a single 400-mg oral dose of racemic IB.     

Towards automation: Radiata pine shoot hedges in vitro

A novel system for in vitro shoot production has been developed whereby shoot hedges are maintained in one vessel. Monthly crops of shoots are produced for rooting. Radiata pine shoot hedges were maintained on Lepoivre (LP) nutrient agar medium for 18 months using a weekly liquid-nutrient replenishment system. In a separate experiment liquid-LP-nutrient replenishment of shoots twice weekly without transfers (D) resulted in better shoot growth and health than monthly transfers to fresh agar medium (B), monthly transfers to fresh agar medium plus aeration twice weekly (C), or no transfers and no liquid nutrient addition (A). Liquid nutrient replenishment twice weekly was better than 2 weekly or 4 weekly replenishment. The percentage of normal waxy (abundant tubular epicuticular wax) shoots harvested monthly increased significantly over the culture period from 41% at the first harvest to 93% at the eight harvest, and remained high at 97% from the ninth to twelfth harvest. The percentage of wet (no tubular epicuticular wax, small amounts of globular epicuticular wax) shoots harvested showed a corresponding decline—from 59%, to 7% at the eighth harvest. Shoots were harvested at a rate of 672/h (1.19 cents/shoot at a labour cost of NZ$8.00/h) and approximately 1100 shoots were produced per square metre of agar surface per month. Initial problems of contamination and crowding were overcome. These results will greatly facilitate progress towards automation of shoot production and reduction of costs of micropropagated trees. An automated system used in combination with other cost-saving techniques or robotics could potentially result in a substantial reduction in costs. This is the first report of a method of culturing shoots as hedges for a period of up to 18 months without manual subculturing.     

Localisation of laminin and fibronectin during rat lens morphogenesis

Abstract. Immunofluorescence clearly localised laminin and fibronectin in the basement membranes of ocular epithelia through all stages of rat lens differentiation. Some fibronectin is also localised around the mesodermal cells associated with the epithelia. At 10 days of embryonic development, the presumptive lens ectoderm and optic veiscle are closely associated, and the "interspace" between the two tissues contains only a few mesodermal cells. Later, as the mesoderm is excluded and the lens palcode invaginates to form the lens pit, there is a marked increase in the concentration of both laminin and fibronectin in the interspace. At about 13 days, the interspace widens, and there is fluorescence for both glycoproteins in the basement membranes of the optic cup and lens vesicle; as the lens capsule thickens, the fluorescence for laminin increases in the latter. The unlabelled peroxidase anti-peroxidase (PAP) method shows that 'blebs' and 'blisters' of basement membranes, particularly from the optic vesicle, appear to give rise to cords of fibronectin- and laminin-positive material. These cords extend into the interspace and are associated with flocculent and fibrillar material. Therefore, the glycoproteins probably combine with other extracellular matrix (ECM) constituents, e.g. collagen, to form a network of fibrils in the interspace. This network must provide good adhesion between the lens placode and the optic vesicle so that invagination is co-ordinated to form the lens pit and the optic cup, respectively. It is suggested that, in addition to providing good adhesion between the tissues, this laminin- and fibronectin-rich ECM may stimulate the formation of basal extensions and cytoplasmic processes, particularly from the lens placode, and therefore, initiate the ectoderm to form lens placode.