Limb-size proportions in Australopithecus afarensis and Australopithecus africanus

Previous analyses have suggested that Australopithecus africanus possessed more apelike limb proportions than Australopithecus afarensis. However, due to the errors involved in estimating limb length and body size, support for this conclusion has been limited. In this study, we use a new Monte Carlo method to (1) test the hypothesis that A. africanus had greater upper:lower limb-size proportions than A. afarensis and (2) assess the statistical significance of interspecific differences among these taxa, extant apes, and humans. Our Monte Carlo method imposes sampling constraints that reduce extant ape and human postcranial measurements to sample sizes comparable to the fossil samples. Next, composite ratios of fore- and hindlimb geometric means are calculated for resampled measurements from the fossils and comparative taxa. Mean composite ratios are statistically indistinguishable (alpha=0.05) from the actual ratios of extant individuals, indicating that this method conserves each sample's central tendency. When applied to the fossil samples, upper:lower limb-size proportions in A. afarensis are similar to those of humans (p=0.878) and are significantly different from all great ape proportions (p< or =0.034), while Australopithecus africanus is more similar to the apes (p> or =0.180) and significantly different from humans and A. afarensis (p< or =0.031). These results strongly support the hypothesis that A. africanus possessed more apelike limb-size proportions than A. afarensis, suggesting that A. africanus either evolved from a more postcranially primitive ancestor than A. afarensis or that the more apelike limb-size proportions of A. africanus were secondarily derived from an A. afarensis-like ancestor. Among the extant taxa, limb-size proportions correspond with observed levels of forelimb- and hindlimb-dominated positional behaviors. In conjunction with detailed anatomical features linked to arboreality, these results suggest that arboreal posture and locomotion may have been more important components of the A. africanus behavioral repertoire relative to that of A. afarensis.     

Stanniectomy attenuates the renin–angiotensin response to hypovolemic hypotension in freshwater eels (<Emphasis Type="Italic">Anguilla rostrata</Emphasis>) but not blood pressure recovery

Plasma Angiotensin II (ANG II) concentrations were measured in SHM (sham-operated 2 weeks) and CSX (corpuscles of Stannius removed 2 weeks) eels before and after the induction of hypovolemic hypotension (HH) by the rapid withdrawal of 8 ml kg bw⁻¹ of caudal venous blood. Baseline (before exsanguination) plasma ANG II concentrations were similar in SHM and CSX eels (81.3 ± 18.8 fmol ml⁻¹ cf. 106 ± 31.6 fmol ml⁻¹, respectively) but the elevation in plasma ANG II following HH (1,732 ± 82 fmol ml⁻¹) was attenuated by CSX (368 ± 127 fmol ml⁻¹) showing that the CS are linked to plasma ANG II concentrations. Plasma ANG II in both groups returned to baseline levels within 48 h. Dorsal aortic blood pressures (DABP) were measured in both experimental groups before, and during the 60 min after, blood withdrawal. A 44% decrease in mean DABP was observed in both SHM and CSX eels within 2 min and followed by similar rapid patterns of recovery of systolic, diastolic, and pulse pressures in both groups during the next 60 min showing that short-term recovery of DABP is not CS-dependent. Stanniectomy increased plasma Ca and K⁺ and decreased plasma Mg, Na⁺, Cl⁻ and osmolality which confirms some earlier observations in eels and other freshwater teleosts.     

ANG II-induced attenuation of salt gland function in Pekin ducks is not catecholamine-dependent

Pekin ducks (Anas platyrhynchos) were bilaterally adrenalectomized (biADX), injected with 1 mg of triamcinolone (TRIAM) kg bw⁻¹ im and given 0.9% saline drinking water during a 24 h recovery period followed by chemical sympathectomy with 6OH DOPA 3 h before the start of experimental observations. Baseline plasma dopamine (DA) concentrations decreased from 283 ± 88.5 pmol ml⁻¹ to 42.4 ± 11.1 pmol ml⁻¹; epinephrine (E) from 142 ± 46 pmol ml⁻¹ to 18.4 ± 9.2 pmol ml⁻¹ and norepinephrine (NE) from 742 ± 84 pmol ml⁻¹ to 406 ± 38 pmol ml⁻¹ 1 day after biADX + TRIAM but before chemical sympathectomy. Baseline MABP increased from 132 ± 3.2 mmHg to 209 ± 14.3 mmHg (P < 0.05) in response to TRIAM. After chemical sympathectomy with 6OH DOPA there was an additional 90% decrease in plasma NE to 42 ± 9.4 pmol ml⁻¹ and a concurrent 60% decrease in MABP to 83.4 ± 6.9 mmHg (P < 0.05). Nasal fluid secretion was maintained by the continuous infusion of hypertonic saline (1,000 mosmol kg H₂O⁻¹ at a rate of 0.3 ml kg⁻¹ min⁻¹). Rates of nasal fluid secretion and fluid electrolyte concentrations were unchanged following biADX + TRIAM + 6OH DOPA. Angiotensin II (ANG II; dose 1 μg kg bw⁻¹ i.v.), attenuated nasal fluid secretion showing that the response to ANG II was not NE- dependent. Plasma NE concentrations decreased following Tyramine i.v. (33 ± 8.5 pmol ml⁻¹) there being no vasopressor response. This is the first report of the ANG II induced attenuation of duck salt gland secretion in the absence of measurable E and NE.     

Ultrahigh bioproductivity from algae

The potential for dramatic increases in bioproductivity in algal photobioreactors relative to current biomass approaches, e.g., for converting sunlight into biofuels, by an unorthodox integration of photonics and biotechnologies is described. The key to greater biomass yields—projected as high as 100 g dry weight m⁻² h⁻¹—is a pronounced heightening of algal flux tolerance, achieved by tailoring the photonic temporal, spectral and intensity characteristics with pulsed light-emitting diodes. Such tailored photonic input is applied in concert with thin-channel ultradense culture photobioreactors with flow patterns that produce rapid light/dark algae exposure cycles. The artificial-light scheme is globally feasible only with electricity generated from renewables. Recent advances in ultra-efficient concentrator photovoltaics, as well as high-performance light-emitting diodes, create a practical reality for converting sunlight into pulsed red light and delivering it to indoor photobioreactors, with characteristic pulse times and intensities optimally suited to the rate-limiting dark reactions of photosynthesis. Cellular engineering built upon recent progress in modifying algal chlorophyll antenna size, in combination with metabolic engineering, could further enhance bioproductivity. The proposed strategy requires no major advances for implementation and adopts existing technologies. Revision submitted to Applied Microbiology and Biotechnology on 25 June 2007.     

Unique butyric acid incorporation patterns for salinosporamides A and B reveal distinct biosynthetic origins

Feeding sodium butyrate (0.25–1 mg/ml) to cultures of Salinispora tropica NPS21184 enhanced the production of salinosporamide B (NPI-0047) by 319% while inhibiting the production of salinosporamide A (NPI-0052) by 26%. Liquid chromatography mass spectrometry analysis of the crude extract from the strain NPS21184 fed with 0.5 mg/ml sodium [U-¹³C₄]butyrate indicated that butyrate was incorporated as a contiguous four-carbon unit into NPI-0047 but not into NPI-0052. Nuclear magnetic resonance analysis of NPI-0047 and NPI-0052 purified from the sodium [U-¹³C₄]butyrate-supplemented culture extract confirmed this incorporation pattern. The above finding is the first direct evidence to demonstrate that the biosynthesis of NPI-0047 is different from NPI-0052, and NPI-0047 is not a precursor of NPI-0052.     

Correlates of preserved CD4(+) T cell homeostasis during natural, nonpathogenic simian immunodeficiency virus infection of sooty mangabeys: implications for AIDS pathogenesis

In contrast to HIV-infected humans, naturally SIV-infected sooty mangabeys (SMs) very rarely progress to AIDS. Although the mechanisms underlying this disease resistance are unknown, a consistent feature of natural SIV infection is the absence of the generalized immune activation associated with HIV infection. To define the correlates of preserved CD4(+) T cell counts in SMs, we conducted a cross-sectional immunological study of 110 naturally SIV-infected SMs. The nonpathogenic nature of the infection was confirmed by an average CD4(+) T cell count of 1,076 +/- 589/mm(3) despite chronic infection with a highly replicating virus. No correlation was found between CD4(+) T cell counts and either age (used as a surrogate marker for length of infection) or viremia. The strongest correlates of preserved CD4(+) T cell counts were a low percentage of circulating effector T cells (CD28(-)CD95(+) and/or IL-7R/CD127(-)) and a high percentage of CD4(+)CD25(+) T cells. These findings support the hypothesis that the level of immune activation is a key determinant of CD4(+) T cell counts in SIV-infected SMs. Interestingly, we identified 14 animals with CD4(+) T cell counts of <500/mm(3), of which two show severe and persistent CD4(+) T cell depletion (<50/mm(3)). Thus, significant CD4(+) T cell depletion does occasionally follow SIV infection of SMs even in the context of generally low levels of immune activation, lending support to the hypothesis of multifactorial control of CD4(+) T cell homeostasis in this model of infection. The absence of AIDS in these "CD4(low)" naturally SIV-infected SMs defines a protective role of the reduced immune activation even in the context of a significant CD4(+) T cell depletion.     

Critical negative regulation of type 1 T cell immunity and immunopathology by signaling adaptor DAP12 during intracellular infection

Transmembrane signaling adaptor DAP12 has increasingly been recognized for its important role in innate responses. However, its role in the regulation of antimicrobial T cell responses has remained unknown. In our current study, we have examined host defense, T cell responses, and tissue immunopathology in models of intracellular infection established in wild-type and DAP12-deficient mice. During mycobacterial infection, lack of DAP12 leads to pronounced proinflammatory and Th1 cytokine responses, overactivation of Ag-specific CD4 and CD8 T cells of type 1 phenotype, and heightened immunopathology both in the lung and lymphoid organs. DAP12-deficient airway APC display enhanced NF-kappaB activation and cytokine responses upon TLR stimulation or mycobacterial infection in vitro. Of importance, adoptive transfer of Ag-loaded DAP12-deficient APC alone could lead to overactivation of transferred transgenic or endogenous wild-type T cells in vivo. We have further found that the immune regulatory role by DAP12 is not restricted only to intracellular bacterial infection, since lack of this molecule also leads to uncontrolled type 1 T cell activation and severe immunopathology and tissue injury during intracellular viral infection. Our study thus identifies DAP12 as an important novel immune regulatory molecule that acts, via APC, to control the level of antimicrobial type 1 T cell activation and immunopathology.