An experimental assessment of landscape configuration effects on frog and toad abundance and diversity in tropical agro-savannah landscapes of southeastern Brazil

Amphibians are an imperiled group of vertebrate animals that typically have biphasic life histories involving a shift from aquatic larval habitats to terrestrial adult habitats. Habitat loss is the greatest threat to amphibians and the importance of the spatial configuration of terrestrial and breeding habitats upon the landscape in determining amphibian persistence is poorly known. The information gap is particularly acute in tropical landscapes that simultaneously host the greatest and most imperiled amphibian fauna on Earth. We installed 125 artificial ponds at different distances from forest fragments embedded in an agricultural matrix in southeastern Brazil. Constructed ponds attracted 13 anuran species; ponds at the forest fragment-matrix transition hosted a greater abundance and higher species richness of frogs and toads than those installed either far from or well within forest fragments. Forest fragments larger than 70 ha in agricultural areas harbored more individuals than smaller fragments. Our results indicate that landscape configuration has an important influence on frog and toad distribution and abundance in tropical agricultural landscapes and we suggest guidelines for maintaining favorable configurations of aquatic and terrestrial habitats for conserving this rich and imperiled species suite.     

Immunoproteomic analyses of outer membrane antigens of Actinobacillus pleuropneumoniae grown under iron-restricted conditions

Actinobacillus pleuropneumoniae, a bacterial pathogen of swine and agent of porcine pneumonia, causes a highly infectious disease of economic importance in the pig industry. Commercial vaccines for A. pleuropneumoniae include whole-cell bacterins and second generation subunit vaccines but they only confer partial protective immunity. Our search for new vaccine candidates identified antigens that are expressed during conditions that mimic infection; the outer membrane (OM) proteome of A. pleuropneumoniae serotype 5b was examined under iron restriction. Quantitative profiling by 2D-DiGE technology revealed that iron restriction induced expression of previously described transferrin binding proteins (TbpA, TbpB) plus four lipoproteins including spermidine/putrescine binding periplasmic protein 1 precursor (PotD2). Immunoproteomic analyses with antisera from na?ve animals and from infected pigs were able to differentiate antigens within the OM proteome that were specifically recognized during A. pleuropneumoniae infection. Immunoblots of iron-restricted profiles detected PotD2, heme-binding protein A (HbpA), and capsule polysaccharide export protein (CpxD) as well as surface antigens TbpA, TbpB, and OmlA. These data identify OM proteins that demonstrate immunogenicity and upregulation under conditions mimicking infection, providing emphasis on lipoproteins as an important class of antigens to exploit for vaccine development for A. pleuropneumoniae.     

Plasma Concentration of Glucosamine and Chondroitin Sulfate in Horses after an Oral Dose

This study was conducted to study absorption of glucosamine (GlucN) and chondroitin sulfate (CS) in horses immediately after feeding. Six mature mares were used in a replicated 3 × 3 Latin-square-designed experiment. The experiment consisted of three 15-day periods, which included 10 days of diet adaptation followed by a 5-day sampling period. Blood was drawn after feeding on one day during each sampling period. Horses were fed a control diet (40% hay, 60% concentrate) balanced to meet NRC requirements for maintenance of mature horses (NRC, Nutrient requirements of horses, 1989). In one experimental diet, 2.0 g CS and 5.5 g GlucN were added to the basal ration at each feeding. In the other experimental diet, 3.5 g CS and 8.5 g GlucN were added to the basal ration at each feeding. After collections, blood was centrifuged and plasma was harvested and stored until analyzed for the presence of each compound. Analyses for plasma GlucN were performed using high-performance liquid chromatography. CS in the plasma was analyzed using a color reagent, dimethylmethylene blue, followed by ultraviolet spectrophotometry. There were no significant differences (P < .05) in the concentration of either CS or GlucN in plasma, when comparing the three different diets. This leads to a conclusion that these compounds were not absorbed intact through the intestinal wall into the bloodstream. This poses a question as to whether oral forms of these compounds are absorbed and are able to migrate to joints through the blood to improve joint function.     

Diverse landscapes have a higher abundance and species richness of spring wild bees by providing complementary floral resources over bees’ foraging periods

Context

Anthropogenic landscape simplification and natural habitat loss can negatively affect wild bees. Alternatively, anthropogenic land-use change may diversify landscapes, creating complementary habitats that maintain overall resource continuity and diversity.

Objectives

We examined the effects of landscape composition, including land-cover diversity and percent semi-natural habitat, on wild bee abundance and species richness within apples, a pollinator-dependent crop. We also explored whether different habitats within diverse landscapes can provide complementary floral resources for bees across space and time.

Methods

We sampled bees during apple bloom over 2 years within 35 orchards varying in surrounding landscape diversity and percent woodland (the dominant semi-natural habitat) at 1 km radii. To assess habitat complementarity in resource diversity and temporal continuity, we sampled flowers and bees within four unique habitats, including orchards, woodlands, semi-natural grasslands, and annual croplands, over three periods from April–June.

Results

Surrounding landscape diversity positively affected both wild bee abundance and richness within orchards during bloom. Habitats in diverse landscapes had different flower communities with varying phenologies; flowers were most abundant within orchards and woodlands in mid-spring, but then declined over time, while flowers within grasslands marginally increased throughout spring. Furthermore, bee communities were significantly different between the closed-canopy habitats, orchards and woodlands, and the open habitats, grasslands and annual croplands.

Conclusions

Our results suggest that diverse landscapes, such as ones with both open (grassland) and closed (woodland) semi-natural habitats, support spring wild bees by providing flowers throughout the entire foraging period and diverse niches to meet different species’ requirements.

     

Inheritance and expression of transgenes in T2 and T3 generations of Lotus corniculatus transformed using Agrobacterium tumefaciens

The inheritance and expression of the reporter gene uidA, encoding β-glucuronidase (GUS), was previously analysed in the T₁ generation of 25 independent transformed lines of Lotus corniculatus cv. Leo. In the work reported here, GUS activity in various tissues of seven of these lines was tested in the T₂ generation. Four representative lines were chosen for more detailed study in the T₃ generation. Lines 25 and 38 had multiple, independently segregating transgene inserts; lines 24 and 39 appeared to transmit one segregating transgene insert to their T₁ progeny, although transgene expression was low and was detected in fewer seedlings than expected in line 39. The uidA gene was inherited and expressed in seedlings of T₁, T₂ and T₃ generations of all four lines. In all lines, transgene expression varied between tissues, with more embryos than seedlings having detectable GUS activity. Studies in the T₂ generation showed that use of transgenic plants as female or male parents altered the frequency of expression of the transgene in progeny. By contrast, in the T₃ generation the use of transgenic plants as female or male parents did not effect either frequency of transmission, or expression of the transgene, in any of the four lines. Transgene inheritance was also similar among individual pods within flower heads and between individual flower heads. This revised version was published online in July 2006 with corrections to the Cover Date.     

Inorganic sediment budget in the mangrove-fringed Fly River Delta,Papua New Guinea

Six oceanographic moorings were maintained for 8 weeks across the mouth of the mangrove-fringed Fly River estuary from April to June 1995 in the southeast trade wind season. A further 4 moorings were deployed for 8 weeks along the estuary channel in 1992, also in the southeast trade wind season. These data were used to estimate net exchange of suspended sediment between the estuary and the Gulf of Papua. A net inflow of fine sediment into the estuary from the coastal ocean was found to be considerable, about 40 tonnes s^-1 or about 10 times the riverine inflow rate, resulting in a calculated, spatially averaged vertical accretion rate of 2 mm year^-1. Mangroves may account for trapping 6% of the riverine sediment inflow or about 1/4 of the riverine clay inflow. If this sediment was distributed only over the observed accumulation zones near islands the local accumulation rates in these zones would reach 4 cm year^-1. Estimates of soft sediment mass accumulation rates (1–10 kg m^-2 year^-1) in the channel from Pb-210 and C-14 measurements from cores of deltaic mangrove mud cannot account for this accumulation rate on a 100–1000 year time scale. The fate of the remaining sediment is unknown, it may be exported from the estuary in the monsoon season.     

A dielectric omnidirectional reflector

A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices.     

Tracking the long-term decline and recovery of an isolated population

Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens.     

Inhibition of Salmonella typhimurium in the chicken intestinal tract by a transformed avirulent avian Escherichia coli.

An avirulent, wild-type avian Escherichia coli (E. coli Av) was electrotransformed with a plasmid coding for the production of microcin 24 (pGOB18) and was designated E. coli AvGOB18. The transformant inhibited the growth of seven serotypes of Salmonella commonly associated with colonization and contamination of poultry products and seven strains of E. coli O157:H7 in the in vitro colicin/microcin assay. The transformant did not inhibit the replication of multiple isolates of Listeria monocytogenes or Campylobacter jejuni in similar assays. The transformant is nonconjugative, indicating that the plasmid would not be transmitted to other intestinal microflora in the environment. The transformant also survived in sterile tap and deionized water incubated at 25 C and 37 C in the laboratory for 30 days and was recovered from drinkers and birds in in vivo floor pen studies. In in vivo studies, E. coli AvGOB18 did not colonize the intestinal tract of broiler chicks when given as a single or multiple dose and did not reduce the Salmonella load in the broilers. But Salmonella typhimurium was reduced significantly in the intestinal tracts of broiler chickens when E. coli AvGOB18 was administered continually in the water supply.     

Assignment of new loci to river buffalo chromosomes confirms the nature of chromosomes 4 and 5

Introduction Rapid development of the river buffalo physical map can be achieved by coupling its development to that of the cattle gene map. Syntenic conservation between cattle and buffalo has been demonstrated, mainly using somatic cell hybrids (de Hondt et al. 1991; El Nahas et al. 1993, 1996, 1998; de Hondt et al. 1997; El Nahta 1996; Oraby et al. 1977), and by using in situ hybridization as reviewed by Iannuzzi (1997). G- and R-banding comparisons between cattle (2n = 60) and river buffalo (2n = 50) chromosomes have revealed a large number of banding homologies between the two species, both at early-metaphase (Gupta and Ray -Chaudhury 1978; Di Berardino et al. 1981) and prometaphase stages (Iannuzzi et al. 1990). Banding homology indicates that the five river buffalo biarmed pairs originate from centric fusion translocation between two of ten homologous cattle autosomes, which is very supportive of the hypothesis that both species have a common ancestor (Wurster and Benirschke 1968). Based on cytological analysis and banding homology between cattle and buffalo chromosomes, the five biarmed chromosomes of the river buffalo BBU1, BBU2, BBU3, BBU4, BBU5 were thought to originate from fusion of cattle chromosome (BTA) 1/25; 2/23; 8/19; 5/28; and 16/29 respectively (Iannuzzi et al. 1990; Report of the Committee for the Standardization of Banded Karyotopes of the River Buffalo 1994). However, the analysis of synteny between molecular markers assigned to different cattle syntenic groups demonstrated that BBU1 results from fusion of BTA 1 and 27 rather than 1 and 25 (El Nahas et al. 1977). This called for expanding the analysis of syntenic relationships between marker loci to confirm the nature of the other biarmed buffalo chromosomes. The purpose of this study is to test synteny between markers in buffalo and to confirm the nature of the biarmed buffalo chromosomes 4 and 5, using marker loci and somatic cell hybrids.