Sulphur-isotope compositions of pig tissues from a controlled feeding study

Sulphur-isotope determinations are becoming increasingly useful for palaeodietary reconstruction, but knowledge of isotopic discrimination between diet and various tissues remains inadequate. In this study, we explore the sensitivity of δ34Stissue values to changes in δ34Sdiet values, sulphur isotopic discrimination between diet and consumer, and the potential impact of terrestrial vs. marine protein consumption on these discrimination offsets. We present new δ34S values of bone collagen, muscle, liver, hair, milk and faeces from ten mature sows, ten piglets and fifteen adolescent pigs from a controlled feeding study. The δ34Stissue values were found to co-vary with the δ34Sdiet values, the δ34Stissue – δ34Sdiet isotopic offsets (Δ34Stissue-diet) are small but consistent, and dietary protein source does not systematically alter the Δ34Stissue-diet isotopic discrimination. The outcomes of this study are of particular relevance to questions that are difficult to resolve using carbon and nitrogen stable isotopes alone, and will also be useful in regions where terrestrial, freshwater, and marine resources could have all potentially contributed to human diet

Age effects and the influence of varying proportions of terrestrial and marine dietary protein on the stable nitrogen-isotope compositions of pig bone collagen and soft tissues from a controlled feeding experiment

In this study, femoral collagen, rib collagen, femoral muscle, loin muscle and liver samples from sows, piglets and pigs raised in a controlled feeding study are analysed for their nitrogen-isotope compositions. The objectives of this research are to investigate the relationship between tissue and dietary δ15N values across age categories under controlled feeding and housing conditions, and to assess tissue 15N-enrichment relative to diet when pigs of different ages are consuming terrestrial, marine, or mixed terrestrial-marine dietary protein. There is a strong linear relationship between all tissue δ15N values and the amount of marine protein consumed, but the δ15N values do not become consistently elevated for all individuals consuming the same diet until at least 25% of the dietary protein source is marine-derived. Adolescent pigs also had consistently lower δ15N values than either piglets or sows consuming the same diet for collagen and muscle, which is most likely caused by the differences in growth rate among the age categories. Further, for some tissues and animals, a linear relationship between the amount of marine protein consumed and the Δ15NTissue – Whole Diet offset was also observed. We suggest that this variability results from both age-associated growth rates and differential incorporation of amino acids from terrestrial and marine dietary protein into rapidly growing tissue

Agriculture: Steps to sustainable livestock

With improved breeding and cultivation, ruminant animals can yield food that is better for people and the planet, say Mark C. Eisler, Michael R. F. Lee and colleagues

Memory versus naive T-cell migration.

Our established understanding of lymphocyte migration suggests that naive and memory T cells travel throughout the body via divergent pathways; naive T cells circulate between blood and lymph whereas memory T cells additionally migrate through non-lymphoid organs. Evidence is now gradually emerging which suggests such disparate pathways between naive and memory T cells may not strictly be true, and that naive T cells gain access to the non-lymphoid environment in numbers approaching that of memory T cells. We discuss here the evidence for naive T-cell traffic into the non-lymphoid environment, compare and contrast this movement with what is known of memory T cells, and finally discuss the functional importance of why naive T cells might access the parenchymal tissues

Subchondral bone plate remodels more rapidly than trabecular bone in osteoarthritis

Objective: To determine the sequence and the relationship between bone remodelling in subchondral bone plate (Sbp) and trabecular bone (Tb), during the development of OA in two spontaneous animal models, the Dunkin Hartley (DH) guinea pig which develop OA around 12 weeks and the Bristol Strain 2 (BS2) which develops OA around 24 weeks of age. Methods: The right tibias were dissected from six male animals of each strain, at 10, 16, 24 and 30 weeks of age. Changes in tibial plateau cartilage were assessed histologically. Micro-computed tomography was used to quantify the growth plate thickness (GpTh), subchondral bone plate thickness (SbpTh) and trabecular bone thickness (TbTh), and bone mineral density (BMD) in both Sbp and Tb. Results: The growth plate was still open by 30 weeks of age in both strains (DH: 151.3µm±17.4, BS2: 153.4µm±15.7) and closure rate of the growth plate was similar prior to 24 weeks. The SbpTh and TbTh were greater in the medial side than the lateral side, and in the DH than BS2. In the DH strain, the bone mineral density (BMD) of Sbp increased between 10 and 16 weeks and then decreased, whereas in BS2 BMD gradually increased over the study period. The rates of SbpTh changes were generally higher in DH than BS2, and in the DH these changes were greater in the medial than lateral side, especially between 10 - 16 weeks (medial side: 22.7µm/week; lateral side: 14.8µm/week). In contrast, in the BS2 SbpTh changes were greater in the lateral side. Similarly, the highest rate of Sbp BMD change was observed in the DH medial side between 10 – 16 weeks (0.07g/cm3). However, after 16 weeks, both Sbp and Tb BMD decreased in the DH strain but not in the BS2 animals. Conclusions: The rapid increase during the early time points and consistently higher rate of increase of SbpTh in the medial side of DH when the medial and lateral sides in both strains showed a similar rate of TbTh suggest that there is more rapid remodelling of the Sbp than Tb during development of OA. The highest rate of BMD increase in the medial side of Sbp in DH between 10 to 16 weeks and a fall in BMD thereafter in both in Sbp and Tb suggest that increased BMD may be associated with initiation of OA but not progression

Increased chondrocyte apoptosis is associated with progression of osteoarthritis in spontaneous Guinea pig models of the disease

Osteoarthritis (OA) is the most common joint disease characterised by degradation of articular cartilage and bone remodelling. For almost a decade chondrocyte apoptosis has been investigated as a possible mechanism of cartilage damage in OA, but its precise role in initiation and/or progression of OA remains to the determined. The aim of this study is to determine the role of chondrocyte apoptosis in spontaneous animal models of OA. Right tibias from six male Dunkin Hartley (DH) and Bristol Strain 2 (BS2) guinea pigs were collected at 10, 16, 24 and 30 weeks of age. Fresh-frozen sections of tibial epiphysis were microscopically scored for OA, and immunostained with caspase-3 and TUNEL for apoptotic chondrocytes. The DH strain had more pronounced cartilage damage than BS2, especially at 30 weeks. At this time point, the apoptotic chondrocytes were largely confined to the deep zone of articular cartilage (AC) with a greater percentage in the medial side of DH than BS2 (DH: 5.7%, 95% CI: 4.2–7.2), BS2: 4.8%, 95% CI: 3.8–5.8), p > 0.05). DH had a significant progression of chondrocyte death between 24 to 30 weeks during which time significant changes were observed in AC fibrillation, proteoglycan depletion and overall microscopic OA score. A strong correlation (p ≤ 0.01) was found between chondrocyte apoptosis and AC fibrillation (r = 0.3), cellularity (r = 0.4) and overall microscopic OA scores (r = 0.4). Overall, the rate of progression in OA and apoptosis over the study period was greater in the DH (versus BS2) and the medial AC (versus lateral). Chondrocyte apoptosis was higher at the later stage of OA development when the cartilage matrix was hypocellular and highly fibrillated, suggesting that chondrocyte apoptosis is a late event in OA