A 'dynamic' landscape of fear: prey responses to spatiotemporal variations in predation risk across the lunar cycle.

Ambiguous empirical support for 'landscapes of fear' in natural systems may stem from failure to consider dynamic temporal changes in predation risk. The lunar cycle dramatically alters night-time visibility, with low luminosity increasing hunting success of African lions. We used camera-trap data from Serengeti National Park to examine nocturnal anti-predator behaviours of four herbivore species. Interactions between predictable fluctuations in night-time luminosity and the underlying risk-resource landscape shaped herbivore distribution, herding propensity and the incidence of 'relaxed' behaviours. Buffalo responded least to temporal risk cues and minimised risk primarily through spatial redistribution. Gazelle and zebra made decisions based on current light levels and lunar phase, and wildebeest responded to lunar phase alone. These three species avoided areas where likelihood of encountering lions was high and changed their behaviours in risky areas to minimise predation threat. These patterns support the hypothesis that fear landscapes vary heterogeneously in both space and time.

Semicircular canal morphogenesis in the zebrafish inner ear requires the function of gpr126 (lauscher), an adhesion class G protein-coupled receptor gene.

Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

The case for fencing remains intact.

Creel et al. argue against the conservation effectiveness of fencing based on a population measure that ignores the importance of top predators to ecosystem processes. Their statistical analyses consider, first, only a subset of fenced reserves and, second, an incomplete examination of 'costs per lion.' Our original conclusions remain unaltered.

Conserving large carnivores: dollars and fence.

Conservationists often advocate for landscape approaches to wildlife management while others argue for physical separation between protected species and human communities, but direct empirical comparisons of these alternatives are scarce. We relate African lion population densities and population trends to contrasting management practices across 42 sites in 11 countries. Lion populations in fenced reserves are significantly closer to their estimated carrying capacities than unfenced populations. Whereas fenced reserves can maintain lions at 80% of their potential densities on annual management budgets of $500 km(-2) , unfenced populations require budgets in excess of $2000 km(-2) to attain half their potential densities. Lions in fenced reserves are primarily limited by density dependence, but lions in unfenced reserves are highly sensitive to human population densities in surrounding communities, and unfenced populations are frequently subjected to density-independent factors. Nearly half the unfenced lion populations may decline to near extinction over the next 20-40 years.

Changes in floodplain hydrology following serial damming of the Tocantins River in the eastern Amazon.

Riparian forests are ecotones that link aquatic and terrestrial habitats, providing ecosystem services including sediment control and nutrient regulation. Riparian forest function is intimately linked to river hydrology and floodplain dynamics, which can be severely altered by dams. The Tocantins River in the eastern Amazon has six mega-dams along its course. To understand the large-scale and cumulative impacts of multiple dams on the Tocantins floodplain, we quantified landscape-scale changes in floodplain extent, hydroperiod, and flood timing on a 145-km stretch of the river downstream of five dams. We used water level data from 1985 to 2019 to compare daily floodplain inundation dynamics before and after damming. We also developed models to examine the impacts of climate and land use change on hydrology of the Tocantins River. After installation of the first dam in 1998, an average of 82.3 km2 (63%) of the floodplain no longer flooded, overall average hydroperiod decreased by 15 days (11%), and flooding started an average of five days earlier. After all five dams were installed, 72% of the average pre-dam flooded area no longer flooded, average hydroperiod had decreased by 35%, and average inundation onset occurred 12 days later. These changes in floodplain hydrology appeared to be driven primarily by dam operations as we found no significant changes in precipitation over the study period. Increasing loss of natural vegetation in the watershed may play a role in changed hydrology but cannot explain the abrupt loss of floodplain extent after the first dam was installed. This is one of few studies to quantify dam-induced floodplain alteration at a landscape scale and to investigate impacts of multiple dams on a landscape. Our results indicate that the Tocantins River floodplain is undergoing drastic hydrologic alteration. The impacts of multiple dams are cumulative and non-linear, especially for hydroperiod and flood timing.

Chemically induced porphyria: prevention by prior treatment with phenobarbital.

The excessive induction of hepatic delta-aminolevulinic acid synthetase in rats after the administration of porphyria-inducing compounds is prevented by prior treatment with phenobarbital. Studies in vivo and in vitro indicate that phenobarbital prevents the induction of chemical porphyria by increasing the rate of detoxification of inducers by way of drug-metabolizing enzymes of the hepatic endoplasmic reticulum.

Selenium: biochemical role as a component of glutathione peroxidase.

When hemolyzates from erythrocytes of selenium-deficient rats were incubated in vitro in the presence of ascorbate or H(2)O(2), added glutathione failed to protect the hemoglobin from oxidative damage. This occurred because the erythrocytes were practically devoid of glutathione-peroxidase activity. Extensively purified preparations of glutathione peroxidase contained a large part of the (75)Se of erythrocytes labeled in vivo. Many of the nutritional effects of selenium can be explained by its role in glutathione peroxidase.

Bidirectional promoter interference between two widely used internal heterologous promoters in a late-generation lentiviral construct.

Gene transfer vectors encoding two or more genes are potentially powerful research tools and are poised to play an increasingly important role in gene therapy applications. Common strategies employed to express more than one transgene per vector include the use of multiple promoters, internal ribosome entry site (IRES) elements, splicing signals and fusion proteins. Of these, the IRES elements and multiple promoters have been most widely used. The use of multiple promoters, however, may be compromised by interference between promoters, promoter silencing and vector rearrangements or deletions. In this study, we demonstrate promoter interference between two internal heterologous promoters in the context of a late-generation lentiviral vector. The interference, involving the human cytomegalovirus-immediate-early promoter and human elongation-factor-1alpha promoter, occurred bidirectionally with both promoters markedly impairing expression of the adjacent transcription unit. The data presented not only highlight the potential for interference between these widely-used promoters, but also the value of a sequential approach to vector construction that allows such effects to be recognized.

An N-linked high-mannose type oligosaccharide, expressed at the major outer membrane protein of Chlamydia trachomatis, mediates attachment and infectivity of the microorganism to HeLa cells.

The structure of the carbohydrate of the 40-kD major outer membrane component of Chlamydia trachomatis and its role in defining infectivity of the organism were investigated. The oligosaccharides were released from the glycoprotein by N-glycanase digestion, coupled to a 2-aminopyridyl residue, and subjected to two-dimensional sugar mapping technique. The major fractions consisted of "high-mannose type" oligosaccharides containing 8-9 mannose residues. Bi- and tri-antennary "complex type" oligosaccharides having terminal galactose were detected as minor components. These oligosaccharides were N-linked and contained no sialic acid. This structural profile is consistent with our previous characterization based on lectin-binding and glycosidase digestion. Functional specificity of identified chlamydial oligosaccharides was analyzed using glycopeptides fractionated from ovalbumin and structurally defined oligosaccharides from other sources. The glycopeptide fraction having high-mannose type oligosaccharide, as compared to those having complex or hybrid-type, showed a stronger inhibitory effect on attachment and infectivity of chlamydial organisms to HeLa cells. Among high-mannose type oligosaccharides, the strongest inhibition was observed with mannose 8 as compared with mannose 6, 7, or 9. These results indicate that a specific high-mannose type oligosaccharide linked to the major outer membrane protein of C. trachomatis mediates attachment and infectivity of the organism to HeLa cells.

The use of ultrasound to assess fetal growth in a guinea pig model of fetal growth restriction.

Fetal growth restriction (FGR) is a common and potentially severe pregnancy complication. Currently there is no treatment available. The guinea pig is an attractive model of human pregnancy as placentation is morphologically very similar between the species. Nutrient restriction of the dam creates growth-restricted fetuses while leaving an intact uteroplacental circulation, vital for evaluating novel therapies for FGR. Growth-restricted fetuses were generated by feeding Dunkin Hartley guinea pig dams 70% of ad libitum intake from four weeks before and throughout pregnancy. The effect of maternal nutrient restriction (MNR) on dams and fetuses was carefully monitored, and ultrasound measurements of pups collected. There was no difference in maternal weight at conception, however by five weeks post conception MNR dams were significantly lighter ( P < 0.05). MNR resulted in significantly smaller pup size from 0.6-0.66 gestation. Ultrasound is a powerful non-invasive tool for assessing the effect of therapeutic interventions on fetal growth, allowing longitudinal measurement of fetuses. This model and method yield data applicable to the human condition without the need for animal sacrifice and will be useful in the translation of therapies for FGR into the clinic.

Structure-activity studies of the carcinogenicities in the mouse and rat of some naturally occurring and synthetic alkenylbenzene derivatives related to safrole and estragole.

Twenty-three naturally occurring and synthetic alkenylbenzene derivatives structurally related to the hepatocarcinogen safrole (1-allyl-3,4-methylenedioxybenzene) were assayed for their hepatocarcinogenicity in mice. Some of these compounds (safrole, estragole, eugenol, anethole, methyleugenol, myristicin, elemicin, and dill and parsley apiols) may be ingested in very small amounts by human as natural components of certain spices, essential oils, or vegetables. Estragole (1-allyl-4-methoxybenzene) and its proximate carcinogenic metabolite 1'-hydroxyestragole, previously shown to induce hepatic tumors when administered to male CD-1 mice only during the preweaning period, also induced hepatic tumors on administration for 12 months in the diet of female CD-1 mice. Eugenol (1-allyl-4-hydroxy-3-methoxybenzene) and anethole (trans-4-methoxy-1-propenylbenzene) were inactive in this assay; they were also inactive when administered i.p. during the preweaning period at total doses of up to 9.45 mumol/mouse to male CD-1 or C57BL/6 x C3H F1 (hereafter called B6C3F1) mice. Methyleugenol (1-ally-3,4-dimethoxybenzene) and its 1'-hydroxy metabolite had activities similar to those of estragole and its 1'-hydroxy metabolite for the induction of hepatic tumors in male B6C3F1 mice treated prior to weaning; 1-allyl-1'-hydroxy-4-methoxynaphthalene was somewhat less active. At the levels tested, myristicin (1-allyl-5-methoxy-3,4-methylenedioxybenzene), elemicin (1-allyl-3,4,5-trimethoxybenzene) and its 1'-hydroxy metabolite, dill apiol (1-allyl-2,3-dimethoxy-4,5-methylenedioxybenzene), parsley apiol (1-allyl-2,5-dimethoxy-3,4-methylenedioxybenzene), 1'-hydroxyallybenzene, 3'-hydroxyanethole, and benzyl and anisyl alcohols had no detectable activity for the initiation of hepatic tumors on administration to male mice prior to weaning. The acetylenic derivative 1'-hydroxy-2',3'-dehydroestragole was much more active than either 1'-hydroxysafrole or 1'-hydroxyestragole when administered to preweanling mice. The 2',3'-oxides of safrole, estragole, eugenol, and 1'-hydroxysafrole, which are metabolites of these alkenylbenzenes, had little or no activity in this test. The 2',3'-oxides of safrole and estragole and their 1'-hydroxy derivatives likewise had little or no activity for the induction of lung adenomas in female A/J mice or for the induction of tumors on repetitive injections s.c. in male Fischer rats. However, the 2',3'-oxides of safrole, estragole, eugenol, 1'-hydroxysafrole, and 1'-hydroxyestragole, when administered topically to female CD-1 mice at relatively high doses, initiated benign skin tumors that could be promoted with croton oil.

Pre-packing of cost effective antibiotic cement beads for the treatment of traumatic osteomyelitis in the developing world - an in-vitro study based in Cambodia.

The developing world often lacks the resources to effectively treat the most serious injuries including osteomyelitis following open fractures or surgical fracture treatment. Antibiotic cement beads are a widely accepted method of delivering antibiotics locally to the infected area following trauma. This study is based in Cambodia, a low income country struggling to recover from a recent genocide. The study aims to test the effectiveness of locally made antibiotic beads and analyse their effectiveness after being gas sterilised, packaged and kept in storage Different antibiotic beads were manufactured locally using bone cement and tested against MRSA bacteria grown from a case of osteomyelitis. Each antibiotic was tested before and after a process of gas sterilisation as well as later being tested after storage in packaging up to 42 days. The gentamicin, vancomycin, amikacin and ceftriaxone beads all inhibited growth of the MRSA on the TSB and agar plates, both before and after gas sterilisation. All four antibiotics continued to show similar zones of inhibition after 42 days of storage. The results show significant promise to produce beads with locally obtainable ingredients in an austere environment and improve cost effectiveness by storing them in a sterilised condition.

The side-chain epoxidation and hydroxylation of the hepatocarcinogens safrole and estragole and some related compounds by rat and mouse liver microsomes.

Safrole, estragole, and their 2',3'-oxides were hydroxylated by hepatic microsomes from rats and mice at the 1'-carbon; trans-anethole was hydroxylated at the 3'-carbon; and safrole, estragole, and their 1'-hydroxy derivatives were epoxidized at the 2',3'-double bond. The 2',3'-epoxidation of eugenol was just detectable. The formation of these metabolites was dependent on an NADPH-generating system and on cytochrome P-450. In the absence of 3,3,3-trichloropropylene oxide little or no safrole-, estragole-, or eugenol-2',3'-oxide was recovered when these oxides were added to the incubations; recoveries of 50-70% were obtained in its presence. The recoveries of the 2',3'-oxides of 1'-hydroxy-safrole and of 1'-hydroxyestragole were 50-80% in the absence of trichloropropylene oxide and nearly quantitative in its presence. All incubations for analysis of epoxidation rates contained trichloropropylene oxide. The rates of metabolite formation ranged from about 0.4 nmol of eugenol-2',3'-oxide/mg protein/h by female rat liver microsomes to about 270 nmol of trans-3'-hydroxyanethole/mg protein/h for male rat liver microsomes. The rates of epoxidation and hydroxylation were greater for the estragole derivatives than for the safrole derivatives. The rates of epoxidation of safrole and estragole were greater than for their 1'-hydroxy derivatives.

Animal models of fetal growth restriction: Considerations for translational medicine.

Fetal growth restriction (FGR) is the failure of a fetus to reach its full genetic growth potential. It occurs in up to 8% of pregnancies, and after premature birth is the second leading cause of infant mortality and morbidity. There is no treatment currently available for FGR. Its primary cause, when not attributable to structural or genetic defects of the fetus, is 'placental insufficiency'. This broad definition covers the inability of the fetus to acquire sufficient nutrients and oxygen, and is influenced by a number of factors including altered maternal or fetal blood flow, reduced nutrient transport or changes in the placenta such as increased barrier thickness inhibiting nutrient transfer. For those researchers studying FGR and developing new therapies, choosing an animal model is a crucial consideration. It is vital to clearly frame the question being asked, as this will impact the factor influencing fetal nutrient delivery in the model, and will also affect the applicability of the results to the human condition. This review examines the range of in vivo models of FGR available for those engaged in translational research.

Proteases in the Emory mouse cataract.

Exopeptidases identified as dipeptidyl peptidase III and leucine aminopeptidase, and an endopeptidase, prolyl endopeptidase, were found in the Emory Mouse cataract and the Cataract Resistant mouse lens extracts. The specific activity measured on Arg-Arg-2-NNap for DPP III and the hydrolysis of Boc-Arg-Pro-2-NNap for prolyl endopeptidase were higher in the Emory Mouse cataractous lens extract. A relatively high rate of hydrolysis of the beta-naphthylamide of leucine aminopeptidase was present in both mouse categories; however, the Cataract Resistant mouse lens had approximately double the protease activity of the Emory Mouse cataract.

A census-based design for the recruitment of a community sample of older adults: efficacy and costs.

PURPOSE: This is a report of the scientific and cost implications of a census-based design to identify residents aged 55 and over for a community study of the effects of aging on physical function. METHODS: A census of residents in a study community was conducted by the use of a mailed questionnaire. For households that did not complete and return the mailed census questionnaire, contact was attempted first by telephone and then by home visit. A comparison was made of the unit costs and characteristics of subjects identified by the different methods. RESULTS: A total of 3509 age-eligible subjects were identified (78.3% by mailer, 19.5% by telephone, and 2.0% by home visit). Costs per enrolled age-eligible subject were lower for mailing and telephone ($7.76 and $4.72 respectively) than for home visit ($36.25). Subjects identified by home visit were significantly younger than subjects identified either by mail or telephone. After adjustment for age, subjects identified by telephone had less education and income and poorer health and functional status than subjects identified by mail. With the exception of age, there were no significant differences between subjects identified by mailer and home visit. CONCLUSIONS: A mailed questionnaire with telephone recontact is a practical strategy for community-based recruitment. Recontact of subjects by telephone can be expected to identify subjects who are not well-represented in a sample based only on a mailer. In contrast, the home visit is expensive and identifies subjects who do not differ meaningfully from those identified by mailer.

Reliability of physical performance and self-reported functional measures in an older population.

BACKGROUND: Functional assessments and direct measures of physical performance are standard components of community-based studies of older populations. Estimates of the reliability of these measures are necessary for the assessment of functional change. METHODS: The reproducibility of 13 measures of self-reported function and 11 direct measures of physical performance was assessed. A sample of subjects (N=199; > or =55 yrs) was selected from a larger population-based cohort. Subjects were tested in their homes twice, 48 hours apart, by the same interviewer to replicate study conditions. Age-adjusted kappa statistics were used to assess the reliability of measures of physical function; product moment correlation (Pearson r) and intraclass correlation coefficients (ICC) were used to assess direct measures of performance. A repeated measures model was used to assess learning or practice effects of performance, adjusted for age, sex, general health, and cognitive function. RESULTS: Age-adjusted kappa statistics were > or = .60 for most self-reported items. ICC ranged from .63 to .92. Significant improvements (practice effects) were found for the chair stand, walking speed, and the 360 degree turn. Measures of grip strength, reaching down, and hand dexterity were found to be reliable, with no significant test effect. CONCLUSION: Three commonly used measures (chair stand, walking speed, and 360 degree turn) may be less reliable than previously reported. Sample sizes that may be needed to detect change in these areas of performance may be larger than previously estimated given this level of imprecision. Future studies of reproducibility should assess both the level of agreement and the presence of possible practice effects.

The 32-kDa glycoprotein of Chlamydia trachomatis is an acidic protein that may be involved in the attachment process.

The 32-kDa glycoprotein of Chlamydia trachomatis was shown to have a pI of 6.2 to 6.4 which distinguished this protein from the chlamydial histone-like protein of similar molecular mass that has a pI of > 10. The initial interaction of the glycan of 32 kDa glycoprotein and HeLa cells was also investigated. Glycan was cleaved from the protein backbone by N-glycanase and radiolabeled with tritium by sodium borohydride reduction. Competition assays showed the binding of glycan to HeLa cells was inhibited by galactose, mannose, and N-acetylglucosamine but not by sedoheptulose and fructose. Untreated and UV-treated organisms inhibited the binding, while heat-inactivated organisms did not. Binding was blocked by rabbit antiserum against whole organisms but not by rabbit anti-155-kDa antiserum or monoclonal antibodies against the lipopolysaccharide and major outer membrane protein.

The 18-kDa lectin-binding protein of Chlamydia trachomatis is different from the 18-kDa histone-like protein.

Five proteins of Chlamydia trachomatis at the 18,000 (18-kDa) molecular mass region were resolved by two-dimensional electrophoresis. Three proteins at 18.2 kDa, pI 6.9, 18.0 kDa, pI 6.3, and 17.9 kDa, pI 6.4 were shown to bind lectin. A fourth protein of 18.0 kDa at pI 10 was the histone-like protein. The fifth protein at 17.9 kDa, pI 7.0 was not characterized.

High-performance liquid chromatography/NMR spectrometry/mass spectrometry: further advances in hyphenated technology.

The earlier use of combined liquid chromatography/NMR spectrometry/mass spectrometry (LC/NMR/MS) involved the use of a particle beam interface. This paper describes further developments of this hyphenated technology, in particular the incorporation of an electrospray interface into the LC/NMR/MS system. This improved LC/NMR/MS system was designed for the support of a combinatorial library program. The power of this technique is demonstrated in the successful structural elucidation of each compound in a mixture of commercially available peptides.