Characterization of the Lysogenic Bacteriophage MAV1 from Mycoplasma arthritidis

The lysogenic bacteriophage MAV1, which is associated with the arthritogenicity of Mycoplasma arthritidis, was characterized. Several strains of M. arthritidis were examined for their ability to support growth of MAV1. A PFU assay was developed, and the sensitivity of phage to various chemical treatments was assayed. The most notable result was the resistance of MAV1 to proteinase K. The MAV1 genome is a double-stranded, linear DNA molecule of about 16 kb. The site of MAV1 DNA integration in the host chromosome was investigated. The ends of MAV1 DNA were cloned from three independent lysogens shown to have MAV1 DNA inserted at different sites in the host. The nucleotide sequences of the ends of the MAV1 genome and of the MAV1 DNA-chromosomal DNA junctions from each of three lysogens were determined. Sequences flanking the integrated prophage and the ends of native MAV1 DNA were determined, allowing the identification of the phage DNA (attP) and bacterial DNA (attB) recombination sites. Analysis of the left MAV1 DNA-chromosomal DNA junction sites showed a single-base heterogeneity located within MAV1 DNA sequences immediately adjacent to the attB sequence. A model for MAV1 integration-excision is proposed.     

Implementing artificial insemination as an effective tool for ex situ conservation of endangered avian species

Approximately 503 of the known species of birds are classified as ‘endangered’ or ‘critical’. Captive propagation programs have proven useful in maintaining genetic diversity and restoring wild populations of certain species, including the Peregrine falcon, California condor and Whooping crane. Artificial insemination (AI) has the potential of solving problems inherent to reproductive management of small, closed populations of endangered birds, including dealing with demographic instability, physical and behavioral disabilities, sexual incompatibility, lack of synchrony, and need to maintain gene diversity. In this review, we address the necessary methods and factors that allow AI to be applied effectively to manage rare bird populations. It is clear that semen availability and quality are the greatest limiting factors to implementing consistently successful AI for birds. Behavioral sensitivity to animal handling and the ability to minimize stress in individual birds also are keys to success. Multiple, deep vaginal inseminations can improve fertility, particularly when semen quality is marginal. Laparoscopic methods of semen transfer also have produced fertile eggs. All of these practices leading to successful AI remain dependent on having adequate basic knowledge on female reproductive status, copulatory behavior, endocrine profiles and duration of fertility, especially as related to oviposition. The overall greatest challenge and highest priority is defining these normative traits, which are highly species-specific.     

Stereoselective inhibition of serotonin re-uptake and phosphodiesterase by dual inhibitors as potential agents for depression

Multi-target compounds where more than one functional activity is incorporated into the same molecule may have advantages in treating disease states. Selective serotonin re-uptake inhibitors (SSRIs)^a (i.e., (R)- and (S)-norfluoxetine) were chemically linked to a PDE4 inhibitor via a five carbon bridge. The new dual PDE4 inhibitor/SSRIs (i.e., (R)-8 and (S)-8) showed moderately potent but highly selective serotonin re-uptake inhibition (IC₅₀ values of 173 and 42 nM, respectively) in vitro. The dual PDE4 inhibitor/SSRIs (R)-8 and (S)-8 also inhibited PDE4D2 (i.e., K_i values of 106 and 253 nM, respectively). Due to the synergistic functional activity, PDE4 inhibitor/SSRIs may be effective in treating diseases such as depression.     

Phylogeny of magpie‐robins and shamas (Aves: Turdidae: Copsychus and Trichixos): implications for island biogeography in Southeast Asia

Aim Magpie‐robins and shamas are forest and woodland birds of south Asia. There are two genera: Trichixos for the monotypic T. pyrrhopygus, and Copsychus for other species. Two species are widespread, whereas the others are restricted to specific islands. Endemicity is highest in the Philippines. Using phylogenetic methods, we examined how this group came to its unusual distribution. Location Mainland Asia from India to southern China, and islands from Madagascar to the Philippines. Particular emphasis is placed on the Greater Sundas and Philippines. Methods The phylogeny was estimated from DNA sequences of 14 ingroup taxa representing all nine currently recognized Copsychus and Trichixos species. The entire mitochondrial ND2 gene and portions of nuclear myoglobin intron 2 (Myo2) and transforming growth factor beta 2 intron 5 (TGFβ2‐5) were sequenced for all but two species. The phylogeny was reconstructed using maximum likelihood and Bayesian methods. The timing of divergence events was estimated using a relaxed molecular clock approach, and ancestral areas were examined using stochastic modelling. Results The group comprises three main clades corresponding to ecological types: Trichixos, a primary‐forest specialist; Copsychus magpie‐robins, open‐woodland and coastal species; and Copsychus shamas, thick‐forest species. Trichixos appears to be sister to the magpie‐robins, rendering Copsychus polyphyletic. The dating of phylogenetic nodes was too ambiguous to provide substantial insight into specific geographical events responsible for divergence within the group. Some patterns are nevertheless clear. Copsychus shamas reached the Philippines, probably in two separate invasions, and split into endemic species. Copsychus malabaricus and C. saularis expanded widely in the Greater Sundas and mainland Southeast Asia without species‐level diversification. Main conclusions Magpie‐robins are excellent dispersers and have diversified into distinct species only on isolated oceanic islands. Trichixos, a poor disperser, is restricted to mature forests of the Malay Peninsula, Sumatra and Borneo. Copsychus shamas are intermediate in habitat preference and dispersal capabilities. Their endemism in the Philippines may be attributed to early colonization and specialization to interior forests. In the Greater Sundas, C. malabaricus and C. saularis populations split and came together on Borneo to form two separate subspecies (of each species), which now hybridize.     

River barriers and cryptic biodiversity in an evolutionary museum

The Riverine Barriers Hypothesis (RBH) posits that tropical rivers can be effective barriers to gene flow, based on observations that range boundaries often coincide with river barriers. Over the last 160 years, the RBH has received attention from various perspectives, with a particular focus on vertebrates in the Amazon Basin. To our knowledge, no molecular assessment of the RBH has been conducted on birds in the Afrotropics, despite its rich avifauna and many Afrotropical bird species being widely distributed across numerous watersheds and basins. Here, we provide the first genetic evidence that an Afrotropical river has served as a barrier for birds and for their lice, based on four understory bird species collected from sites north and south of the Congo River. Our results indicate near‐contemporaneous, Pleistocene lineage diversification across the Congo River in these species. Our results further indicate differing levels of genetic variation in bird lice; the extent of this variation appears linked to the life‐history of both the host and the louse. Extensive cryptic diversity likely is being harbored in Afrotropical forests, in both understory birds and their lice. Therefore, these forests may not be “museums” of old lineages. Rather, substantial evolutionary diversification may have occurred in Afrotropical forests throughout the Pleistocene, supporting the Pleistocene Forest Refuge Hypothesis. Strong genetic variation in birds and their lice within a small part of the Congo Basin forest indicates that we may have grossly underestimated diversity in the Afrotropics, making these forests home of substantial biodiversity in need of conservation.     

The biogeographic history of Phoenicurus redstarts reveals an allopatric mode of speciation and an out-of-Himalayas colonization pattern

Montane areas host high levels of diversity and endemism, and these features are tied to habitat stratification along an elevational gradient. As such, montane areas are often thought of as model systems in which sympatric speciation can occur. To test this idea, we selected Phoenicurus redstarts, an avian genus with an extensive distribution across Eurasia, as well as Northwest Africa; nine of the 14 species in the genus have distributions which include the Himalayas. We used sequences of the mtDNA ND2 and cytochrome-b genes and intron 9 of the Z chromosome specific ACO1 gene to reconstruct a phylogeny of the genus. The resulting trees were used to reconstruct a biogeographic history of Phoenicurus, and to date diversification events. We also analysed the relationship between node age and sympatry to determine the geographic mode of speciation in the genus. Our data suggest a very late Miocene, Himalayan origin for Phoenicurus. Diversification and colonization of other parts of Eurasia, as well as Northwest Africa, continued through the Pleistocene, with a rapid pulse of speciation in the late Pliocene. Allopatric speciation was the dominant mode of speciation in Phoenicurus, despite extensive distributional overlaps in the Himalayas where ecological conditions are amenable to speciation in sympatry. Our results, along with several other studies, suggest an emerging pattern where the Himalayas served as a source area for montane specialist avian lineages that subsequently colonized other Palaearctic regions.     

Two silicone nontoxic fouling release coatings: Hydrosilation cured PDMS and CaCO3 filled,ethoxysiloxane cured RTV11

Two silicone coatings have been evaluated for barnacle adhesion. One coating is an unfilled hydrosilation cured polydimethylsiloxane (PDMS) network, while the other is a room temperature vulcanized (RTV), filled, ethoxysiloxane cured PDMS elastomer, RTV11^?. The adhesion strength of one species of barnacle, Balanus eburneus, to the hydrosilation coatings is in the range of 0.37–0.60 kg cm^‐2 while the corresponding range for RTV11 is 0.64–0.90 kg cm^‐2. The easier release of B. eburneus from the hydrosilation cured network compared to RTV11 is discussed in relationship to differences in bulk and surface properties. Preliminary results suggest bulk modulus may be the most important parameter in determining barnacle adhesion strength. In light or mechanical property analysis, a re‐evaluation of surface properties and chemical stability is presented.     

Does the niche breadth or trade‐off hypothesis explain the abundance–occupancy relationship in avian Haemosporidia?

Two hypotheses have been proposed to explain the abundance–occupancy relationship (AOR) in parasites. The niche breadth hypothesis suggests that host generalists are more abundant and efficient at colonizing different host communities than specialists. The trade‐off hypothesis argues that host specialists achieve high density across their hosts' ranges, whereas generalists incur the high cost of adaptation to diverse immuno‐defence systems. We tested these hypotheses using 386 haemosporidian cytochrome‐b lineages (1894 sequences) recovered from 2318 birds of 103 species sampled in NW Africa, NW Iberia, W Greater Caucasus and Transcaucasia. The number of regions occupied by lineages was associated with their frequency suggesting the presence of AOR in avian Haemosporidia. However, neither hypothesis provided a better explanation for the AOR. Although the host generalist Plasmodium SGS1 was over three times more abundant than other widespread lineages, both host specialists and generalists were successful in colonizing all study regions and achieved high overall prevalence.     

Measurement of lysophospholipid acyltransferase activities using substrate competition

Lysophospholipid acyltransferases (LPATs) incorporate fatty acyl chains into phospholipids via a CoA-dependent mechanism and are important in remodeling phospholipids to generate the molecular species of phospholipids found in cells. These enzymes use one lysophospholipid and one acyl-CoA ester as substrates. Traditional enzyme activity assays engage a single substrate pair, whereas in vivo multiple molecular species exist. We describe here an alternative biochemical assay that provides a mixture of substrates presented to the microsomal extracts. Microsomal preparations from RAW 264.7 cells were used to compare traditional LPAT assays with data obtained using a dual substrate choice assay using six different lysophospholipids and eight different acyl-CoA esters. The complex mixture of newly synthesized phospholipid products was analyzed using LC-MS/MS. Both types of assays provided similar results, but the dual choice assay provided information about multiple fatty acyl chain incorporation into various phospholipid classes in a single reaction. Engineered suppression of LPCAT3 activity in RAW 264.7 cells was easily detected by the dual choice method. These findings demonstrate that this assay is both specific and sensitive and that it provides much richer biochemical detail than traditional assays.