A Zooarchaeological Test for Dietary Resource Depression at the End of the Classic Period in the Petexbatun,Guatemala

Zooarchaeological analyses of animal remains from the Petexbatun sites in the Guatemalan lowlands provide proxy evidence to test a hypothesis of dietary insufficiency during the Maya “collapse.” Ecological foraging theory and resource depression models are used to interpret animal use patterns before and after the disintegration of the Petexbatun polity at the end of the Late Classic period (around a.d. 800). Environmental failure models of the Maya “collapse” at the end of the Late Classic imply that a dietary insufficiency, and particularly a lack of animal resources, was associated with the political and social transitions of this period. However, the results of this zooarchaeological study do not support this hypothesis and point instead to very limited early reductions of only highest-ranked dietary species. The lack of evidence for specific resource depression associated directly with the period of political collapse does not support a model of environmental failure during political disintegration in the Petexbatun. Correlations are found between animal use patterns and the specifics of site size and periods of peak political activity, suggesting that small-scale resource depressions might have resulted at some sites during early periods of human population growth, site expansion, and increasing political activity.     

Immunolocalization of MMP-19 in the human intervertebral disc: implications for disc aging and degeneration

Matrix metalloproteinases (MMPs) degrade components of the extracellular matrix of the disc, but the presence of MMP-19 has not been explored. In other tissues, MMP-19 is known to act in proteolysis of the insulin-like growth factor (IGF) binding protein-3, thereby exposing this protein to make it available to influence cell behavior. MMP-19 also has been shown to inhibit capillary-like formation and thus play a role in the avascular nature of the disc. Using immunohistochemistry, normal discs from six subjects aged newborn through 10 years and 20 disc specimens from control donors or surgical patients aged 15-76 (mean age 40.2 years) were examined for immunolocalization of MMP-19; six Thompson grade I discs, five Thompson grade II, eight Thompson grade III, five Thompson grade IV, and one Thompson grade V discs were analyzed. The results indicate that in discs from young subjects, MMP-19 was uniformly localized in the outer annulus. In discs from adult donors and surgical patients, outer and inner annulus cells only occasionally showed MMP-19 localization. The greatest expression of MMP-19 was observed in young discs, and little expression was seen in older or degenerating discs. Because MMP-19 has been shown to regulate IGF-mediated proliferation in other tissues, its decline in the aging/degenerating disc may contribute to the age-related decrease in disc cell numbers.     

Invasion in space and time: non-native species richness and relative abundance respond to interannual variation in productivity and diversity

Ecologists have long sought to understand the relationships among species diversity, community productivity and invasion by non‐native species. Here, four long‐term observational datasets were analyzed using repeated measures statistics to determine how plant species richness and community resource capture (i.e. productivity) influenced invasion. Multiple factors influenced the results, including the metric used to quantify invasion, interannual variation and spatial scale. Native richness was positively correlated with non‐native richness, but was usually negatively correlated with non‐native abundance, and these patterns were stronger at the larger spatial scale. Logistic regressions indicated that the probability of invasion was reduced both within and following years with high productivity, except at the desert grassland site where high productivity was associated with increased invasion. Our analysis suggests that while non‐natives were most likely to establish in species rich communities, their success was diminished by high resource capture by the resident community.     

Interleukin-7 deficiency in rheumatoid arthritis: consequences for therapy-induced lymphopenia

We previously demonstrated prolonged, profound CD4⁺ T-lymphopenia in rheumatoid arthritis (RA) patients following lymphocyte-depleting therapy. Poor reconstitution could result either from reduced de novo T-cell production through the thymus or from poor peripheral expansion of residual T-cells. Interleukin-7 (IL-7) is known to stimulate the thymus to produce new T-cells and to allow circulating mature T-cells to expand, thereby playing a critical role in T-cell homeostasis. In the present study we demonstrated reduced levels of circulating IL-7 in a cross-section of RA patients. IL-7 production by bone marrow stromal cell cultures was also compromised in RA. To investigate whether such an IL-7 deficiency could account for the prolonged lymphopenia observed in RA following therapeutic lymphodepletion, we compared RA patients and patients with solid cancers treated with high-dose chemotherapy and autologous progenitor cell rescue. Chemotherapy rendered all patients similarly lymphopenic, but this was sustained in RA patients at 12 months, as compared with the reconstitution that occurred in cancer patients by 3–4 months. Both cohorts produced naïve T-cells containing T-cell receptor excision circles. The main distinguishing feature between the groups was a failure to expand peripheral T-cells in RA, particularly memory cells during the first 3 months after treatment. Most importantly, there was no increase in serum IL-7 levels in RA, as compared with a fourfold rise in non-RA control individuals at the time of lymphopenia. Our data therefore suggest that RA patients are relatively IL-7 deficient and that this deficiency is likely to be an important contributing factor to poor early T-cell reconstitution in RA following therapeutic lymphodepletion. Furthermore, in RA patients with stable, well controlled disease, IL-7 levels were positively correlated with the T-cell receptor excision circle content of CD4⁺ T-cells, demonstrating a direct effect of IL-7 on thymic activity in this cohort.     

Diet and reproductive function in wild female chimpanzees (Pan troglodytes schweinfurthii) at Kibale National Park, Uganda

Human female reproductive function is highly sensitive to current energetic condition, indicating adaptation to modulate reproductive effort in accordance with changing ecological conditions that might favor or disfavor the production of offspring. Here, we test the hypothesis that reproductive capacity in female chimpanzees is likewise limited by current energetic condition. We used 12 years of data on wild chimpanzees (Pan troglodytes schweinfurthii) in the Kanyawara community of Kibale National Park, Uganda, to examine the relationship of dietary quality, as assessed by fruit components of the diet, to the occurrence of sexually receptive females, concentrations of ovarian steroid hormones, and timing of conception. We found that the frequency of females having sexual swellings was positively related to the consumption of drupe fruits. Estrogen levels of both cycling and noncycling females increased during seasonal peaks in the consumption of drupe fruits. When average fruit consumption remained high across months, females conceived more quickly. These results support the hypothesis that cycling and conception in chimpanzees are contingent upon high energy balance, and they indicate that the availability of fruit is a key variable limiting reproductive performance in chimpanzees. Chimpanzees appear to share with humans a reproductive system that is primed to respond to proximate levels of energy acquisition.     

The importance of sand albedo for the thermal conditions on sea turtle nesting beaches

At Ascension Island and Cyprus, major nesting areas for green turtles ( Chelonia mydas ) in the Atlantic and Mediterranean, respectively, visual inspection shows some beaches are light in colour while others are darker. We objectively measured the albedo of the sand on different beaches, i.e. the percentage of the incident solar radiation that was reflected from the sand surface. At sites where albedo was recorded, we also measured the temperature of the sand at nest depths. At both rookeries, the sand temperature was markedly higher on darker beaches due to greater absorption of the incident solar radiation over the diurnal cycle. Temperature loggers buried at nest depths revealed seasonal changes in temperature on both islands, but showed that the lowest temperatures found on the darker beaches rarely dropped below the highest temperatures on the lighter beaches. Sea turtles exhibit temperature-dependent sex determination. Since sand albedo is a major avenue for the production of a range of incubation temperatures on both islands, it will also have profound implications for hatchling sex ratios. In comparison with both Ascension Island and Cyprus, for samples collected from sea turtle rookeries around the world there was an even greater range in sand albedo values. This suggests that sand albedo, a factor that has previously received little consideration, will have profound implications for nest temperatures, and hence hatchling sex ratios, for other populations and species.     

Isolation of the gene encoding pilin of Bacteroides nodosus (strain 198), the causal organism of ovine footrot

The gene for pilin, the monomeric protein subunit from which the pilus of Bacteroides nodosus is constructed, has been isolated. Isolation was achieved by cloning the fragmented genome of B. nodosus in Escherichia coli RR1 using the plasmid vector pBR322. Pilin-producing colonies were identified by screening with a colony immunoassay using antiserum from a sheep immunized against purified pili from B. nodosus strain 198, and were further characterized by immunoblot analysis. Final confirmation of the presence of the pilin gene was by nucleotide sequence data which translated to the known pilin amino acid sequence.     

Ascertainment and Prevention of Genetic Disease

A genetic register system has been developed for the ascertainment and prevention of genetic disease. Its potential value is illustrated with data collected from 478 families with serious genetic disorders which had been seen during the past five years. Of these 249 were referred specifically for genetic counselling, autosomal dominant disorders accounting for the largest group of families with individuals at high risk of becoming affected. Of 717 individuals at high risk of having affected children (or carrier daughters in the case of X-linked recessive disorders), only 101 were referred specifically for counselling. Many were referred only after the birth of an affected child which might otherwise have been prevented. A genetic register system linked to practitioner, hospital, and health department records could be a valuable means of preventing genetic disease.