New species of Peliosanthes,Rohdea and Tupistra (Asparagaceae) from Laos and Vietnam

We describe and illustrate four new species, Peliosanthes choriandra, P. tatianae and Tupistra orlovii from central to northern Laos, and Rohdea filosa from northern Vietnam. These are all very local in distribution and endemic to the respective countries. We also report new localities and their ecological conditions for five other species of Peliosanthes (P. argenteostriata, P. hirsuta, P. irinae, P. micrantha and P. nivea) recently described from Laos and/or Vietnam. Furthermore, Peliosanthes nivea is recorded as new to the flora of Laos.     

The Sudden Dominance of bla CTX–M Harbouring Plasmids in Shigella spp. Circulating in Southern Vietnam

Background

Plasmid mediated antimicrobial resistance in the Enterobacteriaceae is a global problem. The rise of CTX-M class extended spectrum beta lactamases (ESBLs) has been well documented in industrialized countries. Vietnam is representative of a typical transitional middle income country where the spectrum of infectious diseases combined with the spread of drug resistance is shifting and bringing new healthcare challenges.

Methodology

We collected hospital admission data from the pediatric population attending the hospital for tropical diseases in Ho Chi Minh City with Shigella infections. Organisms were cultured from all enrolled patients and subjected to antimicrobial susceptibility testing. Those that were ESBL positive were subjected to further investigation. These investigations included PCR amplification for common ESBL genes, plasmid investigation, conjugation, microarray hybridization and DNA sequencing of a bla _CTX–M encoding plasmid.

Principal Findings

We show that two different bla _CTX-M genes are circulating in this bacterial population in this location. Sequence of one of the ESBL plasmids shows that rather than the gene being integrated into a preexisting MDR plasmid, the bla _CTX-M gene is located on relatively simple conjugative plasmid. The sequenced plasmid (pEG356) carried the bla _CTX-M-24 gene on an ISEcp1 element and demonstrated considerable sequence homology with other IncFI plasmids.

Significance

The rapid dissemination, spread of antimicrobial resistance and changing population of Shigella spp. concurrent with economic growth are pertinent to many other countries undergoing similar development. Third generation cephalosporins are commonly used empiric antibiotics in Ho Chi Minh City. We recommend that these agents should not be considered for therapy of dysentery in this setting.     

Peptides panned from a phage-displayed random peptide library are useful for the detection of Bacillus anthracis surrogates B. cereus 4342 and B. anthracis Sterne

Recent use of Bacillus anthracis as a bioweapon has highlighted the need for a sensitive monitoring system. Current bacterial detection tests use antibodies as bio-molecular recognition elements which have limitations with regard to time, specificity and sensitivity, creating the need for new and improved cost-effective high-affinity detection probes. In this study, we screened a commercially available bacteriophage-displayed random peptide library using Bacillus cereus 4342 cells as bait to identify peptides that could be used for detection of Bacillus. The method enabled us to identify two 12-amino acid consensus peptide sequences that specifically bind to B. cereus 4342 and B. anthracis Sterne, the nonpathogenic surrogates of B. anthracis strain. The two Bacillus-binding peptides (named BBP-1 and BBP-2) were synthesized with biotin tag to confirm their binding by four independent detection assays. Dot-blot analysis revealed that the peptides bind specifically to B. cereus 4342 and B. anthracis Sterne. Quantitative analysis of this interaction by ELISA and fluorometry demonstrated a detection sensitivity of 10² colony forming U/ml (CFU/ml) by both assays. When the peptides were used in combination with Qdots, the sensitivity was enhanced further by enabling detection of even a single bacterium by fluorescence microscopy. Immunoblot analysis and protein sequencing showed that BBP-1 and BBP-2 bound to the S-layer protein of B. anthracis Sterne. Overall, our findings validate the usefulness of synthetic versions of phage-derived peptides in combination with Qdot-liquid nanocrystals as high sensitivity bioprobes for various microbial detection platforms.     

Arabidopsis GIGANTEA protein is post-transcriptionally regulated by light and dark

GIGANTEA (GI) is a key regulator of photoperiodic flowering in Arabidopsis and encodes a protein with no domains of known biochemical function. Expression of GI mRNA is controlled by the circadian clock, but GI protein accumulation has not been previously investigated. We generated plants that produced functional epitope-tagged GI to enable us to track the protein through the daily cycle. Here we show that GI protein levels oscillate when either constitutively overexpressed or driven by its promoter and that its accumulation is modulated by day length as well as by phase-specific factors. Also, we demonstrate that one of the mechanisms underlying GI protein oscillation occurs post-translationally via dark-induced proteolysis by the 26S proteasome.     

The endocrinology of pregnancy and fetal loss in wild baboons

An impressive body of research has focused on the mechanisms by which the steroid estrogens (E), progestins (P), and glucocorticoids (GC) ensure successful pregnancy. With the advance of non-invasive techniques to measure steroids in urine and feces, steroid hormones are routinely monitored to detect pregnancy in wild mammalian species, but hormone data on fetal loss have been sparse. Here, we examine fecal steroid hormones from five groups of wild yellow baboons (Papio cynocephalus) in the Amboseli basin of Kenya to compare the hormones of successful pregnancies to those ending in fetal loss or stillbirth. Using a combination of longitudinal and cross-sectional data, we analyzed three steroid hormones (E, P, GC) and related metabolites from 5 years of fecal samples across 188 pregnancies. Our results document the course of steroid hormone concentrations across successful baboon pregnancy in the wild and demonstrate that fecal estrogens predicted impending fetal loss starting 2 months before the externally observed loss. By also considering an additional 450 pregnancies for which we did not have hormonal data, we determined that the probability for fetal loss for Amboseli baboons was 13.9%, and that fetal mortality occurred throughout gestation (91 losses occurred in 656 pregnancies; rates were the same for pregnancies with and without hormonal data). These results demonstrate that our longstanding method for early detection of pregnancies based on observation of external indicators closely matches hormonal identification of pregnancy in wild baboons.     

Position 4 analogues of [deamino-Cys(1)] arginine vasopressin exhibit striking species differences for human and rat V(2)/V(1b) receptor selectivity.

Arginine vasopressin (AVP) mediates a wide variety of biological actions by acting on three distinct G-protein coupled receptors, termed V(1a) (vascular), V(1b) (pituitary) and V(2) (renal). It also binds to the oxytocin (OT) receptor. As part of a program aimed at the design of selective agonists for the human V(1b) receptor, we recently reported the human V(1b), V(1a), V(2) and OT receptor affinities of the following position 4 substituted analogues of [deamino-Cys(1)] arginine vasopressin (dAVP)-(1) d[Leu(4)]AVP, (2) d[Orn(4)]AVP, (3) d[Lys(4)]AVP, (4) d[Har(4)]AVP, (5) d[Arg(4)]AVP, (6) d[Val(4)]AVP, (7) d[Ala(4)]AVP, (8) d[Abu(4)]AVP, (9) d[Nva(4)]AVP, (10) d[Nle(4)]AVP, (11) d[Ile(4)]AVP, (12) d[Phe(4)]AVP, (13) d[Asn(4)]AVP, (14) d[Thr(4)]AVP: (15) d[Dap(4)]AVP. With the exception of Nos. 7 and 12, all peptides exhibit very high affinities for the human V(1b) receptor. Furthermore, peptides 1-4 exhibit high selectivities for the human V(1b) receptor with respect to the V(1a), V(2) and OT receptors and, with d[Cha(4)]AVP, in functional tests, are the first high affinity selective agonists for the human V(1b) receptor (Cheng LL et al., J. Med. Chem. 47: 2375-2388, 2004). We report here the pharmacological properties of peptides 1-4, 5 (from a resynthesis), 7, 9-13, 15 in rat bioassays (antidiuretic, vasopressor and oxytocic) (in vitro: no Mg(++)) with those previously reported for peptides 5, 6, 8, 14. We also report the rat V(1b), V(1a), V(2) and OT receptor affinities of peptides 1-5 and the rat V(2) receptor affinities for peptides: 7-15.The antidiuretic activities in units/mg of peptides 1-15, are: 1=378; 2=260; 3=35; 4=505; 5=748; 6=1150; 7=841; 8=1020; 9=877; 10=1141; 11=819, 12=110; 13=996; 14=758; 15=1053. Peptides 1-4 exhibit respectively the following rat and human (in brackets) V(2) receptor affinities: 1=3.1 nm (245 nm); 2=3.4 nm (1125 nm); 3=24.6 nm (11,170 nm); 4=0.6 nm (1386 nm). Their rat V(1b) receptor affinities are 1=0.02 nm; 2=0.45 nm; 3=9.8 nm; 4=0.32 nm. Their rat V(1a) receptor affinities are 1=1252 nm; 2=900 nm; 3=1478 nm; 4=32 nm. Their rat oxytocin (OT) receptor affinities are 1=481 nm; 2=997 nm; 3=5042 nm; 4=2996 nm. All four peptides have high affinities and selectivities for the rat V(1b) receptor with respect to the rat V(1a) and OT receptors. However, in contrast to their high selectivity for the human V(1b) receptor with respect to the human V(2) receptor, they are not selective for the V(1b) receptor with respect to the V(2) receptor in the rat. These findings confirm previous observations of profound species differences between the rat and human V(2) receptors. Peptides 1-4 are promising leads to the design of the first high affinity selective agonists for the rat V(1b) receptor.     

The fig wax scale Ceroplastes rusci (Linnaeus) (Homoptera: Coccidae) in south-east Vietnam: Pest status, life history and biocontrol trials with Eublemma amabilis Moore (Lepidoptera: Noctuidae)

The fig wax scale Ceroplastes rusci (Linnaeus) is a serious pest of fruit trees in many countries. In the present study we investigated the extent of C. rusci infestation and the range of host species, particularly in fruit orchards, in south‐east Vietnam. Captive populations of C. rusci were established to record life history parameters and to investigate the efficacy of an endemic predacious moth, Eublemma amabilis Moore, as a potential biocontrol agent. Heavy infestation of C. rusci (up to 100%) was recorded in soursop and other fruit orchards, and the culturally important Hoa Mai flower was also affected. Captive breeding trials found E. amabilis to be an efficient predator of C. rusci, but an unusual hyperactive trait in early instars of E. amabilis resulted in lower than expected survival rates. The implications of this trait in terms of the laboratory environment, augmentative release protocols and as a survival strategy are discussed.