条纹短攀鲈的交配习性和筑巢生境

条纹短攀鲈栖息于静止、植被茂密、靠近稻田和池塘边缘的浅水中。本文研究了它在泰国稻田和小池塘两种生境中的繁殖特征。与池塘相比,稻田筑巢地的pH值、溶解氧的含量和温度较高,而电导、溶解的固体物浓度较低,水也较浅。稻田中的种群密度低于池塘。雄性个体的体重和体长均大于雌性个体,且其体重与体长和体宽正相关,但雌性个体的体重仅与体长正相关;泡巢的面积与雄性个体的体长和重量均不相关。繁殖期间,条纹短攀鲈雌、雄个体交尾多次。每次交尾产卵3.74±1.02(Mean±SD)粒,每个繁殖季节交尾84±12.97次;在一个持续178±51.17min的产卵时段里,条纹短攀鲈平均产卵314±109.77粒。鱼苗孵化需30.75±0.55h,2日龄个体的大小平均为3.21±0.29mm。     

Biomimetic one-pot synthesis of vinblastine: NAD(P)H-mediated vinblastine synthesis from the product of FMN-mediated vindoline–catharanthine coupling under near-ultraviolet light

Vinblastine (VLB) is an antineoplastic agent contained in leaves of Catharanthus roseus. One-pot synthesis of VLB from vindoline and catharanthine, biosynthetic precursors in the plant, was achieved under biomimetic conditions. FMN-mediated coupling of vindoline and catharanthine under irradiation with near-ultraviolet light was followed by NAD(P)H-mediated direct conversion of the coupling product to VLB in the dark. The yield of VLB was governed by the level of NAD(P)H added, and the highest yield was obtained by incubation with 10 mM NAD(P)H for 5 h. It is postulated, as one concept of VLB biosynthesis, that similar non-enzymic VLB synthesis may occur in the plant leaves.     

Detection of <Emphasis Type="Italic">Rickettsia</Emphasis> and a Novel <Emphasis Type="Italic">Haemaphysalis shimoga</Emphasis> Symbiont Bacterium in Ticks in Thailand

In this study, we identified two Haemaphysalis species present at the Khao Yai National Park in Thailand and investigated the presence of rickettsia in these ticks. A total of 166 Haemaphysalis specimens were collected randomly under leaves along visitor paths at five locations in the park. Male and female adults of two different Haemaphysalis species, H. shimoga and H. lagrangei, were identified. Polymerase chain reaction (PCR) analysis revealed Rickettsia bacteria in these two Haemaphysalis species; this study represents the first time such presence has been reported in Thailand. The infection rates of Rickettsia were in both H. shimoga (7.41%) and H. lagrangei (10.17%) at these locations in addition to two pools of Haemahysalis nymphs (28.57%). Furthermore, 25.93% of H. shimoga showed positive results that matched Haemaphysalis longicornis symbionts (92% sequence identity) and the Coxeilla burnetti 16S ribosomal RNA gene (90% sequence identity). We propose that this is a novel H. shimoga symbiont bacterium in Thailand and might be a novel Coxeilla-like agent or Coxeilla sp. found in H. shimoga. In contrast, we did not observe any Wolbachia bacteria, which also belong to the order Rickettsiales, in the same group of Haemaphysalis ticks. Furthermore, PCR was used to detect three other genera of bacteria, Anaplasma, Ehrlichia and Borrelia, none of which were identified in the Haemaphysalis ticks studied.     

条纹短攀鲈的雄性个体大小、雌性偏好以及雄性之间的竞争

本研究考察了条纹短攀鲈(Trichopsis vittata)雄性个体的身体大小对雌性个体性偏好的影响以及对雄性之间竞争的影响。本研究设立了两种处理来研究雌性个体的性偏好以及雄性之间的竞争。在一种处理中,放入同样大小的雄性个体,而在另一种处理中,放入大小不同的雄性个体。结果表明,雄性个体的大小不影响雌性条纹短攀鲈的性偏好。在对雄性之间竞争的研究中,发现个体较大的个体获胜的次数比较多。在个体大小相同的处理中,雄性之间打斗的持续时间比另一种处理中的打斗持续时间长。对这两种处理中不同对抗行为的比较表明,个体大小相同处理组中的发声、咬、以及总体对抗行为发生得更为频繁。对个体大小不同处理组中的大、小个体的进一步观察也揭示出体型大的个体比体型小的个体有更多的追逐行为和更少的逃脱行为。这些结果表明,在雄性个体比雌性个体大的物种中,体型的性两型可能与雄性之间的竞争有关,而不是与雌性偏好有关。     

Inverse Association of Plasma IgG Antibody to Aggregatibacter actinomycetemcomitans and High C-Reactive Protein Levels in Patients with Metabolic Syndrome and Periodontitis

The association between clinically diagnosed periodontitis, a common chronic oral infection, and metabolic syndrome has been previously reported. The aim of this study was to investigate the association of plasma IgG levels against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia, C-reactive protein, and periodontal status with metabolic syndrome. Plasma IgG levels and C-reactive protein were measured by enzyme-linked immunosorbent assay, and salivary levels of A. actinomycetemcomitans and P. gingivalis were determined by quantitative real-time polymerase chain reaction. Among 127 individuals aged 35–76 years, 57 participants had metabolic syndrome and severe periodontitis, 25 had metabolic syndrome and an absence of severe periodontitis, 17 healthy individuals had severe periodontitis, and 28 healthy individuals were without severe periodontitis. Patients with metabolic syndrome had reduced humoral immune response to A. actinomycetemcomitans (p = 0.008), regardless of their salivary levels or periodontitis status compared with healthy participants. The IgG antibody response to P. gingivalis, regardless of their salivary levels or participants’ health condition, was significantly higher in severe periodontitis patients (p<0.001). Plasma IgG titers for P. intermedia were inconsistent among metabolic syndrome or periodontal participants. Our results indicate that the presence of lower levels of IgG antibodies to A. actinomycetemcomitans (OR = 0.1; 95%CI 0.0–0.7), but not P. gingivalis, a severe periodontitis status (OR = 7.8; 95%CI 1.1–57.0), high C-reactive protein levels (OR = 9.4; 95%CI 1.0–88.2) and body mass index (OR = 3.0; 95%CI 1.7–5.2), are associated with the presence of metabolic syndrome. The role of the decreased IgG antibody response to A. actinomycetemcomitans, increased C-reactive protein levels on the association between periodontal disease and metabolic syndrome in a group of Thai patients is suggested.     

The methyltransferase domain of dengue virus protein NS5 ensures efficient RNA synthesis initiation and elongation by the polymerase domain

Viral RNA-dependent RNA polymerases (RdRps) responsible for the replication of single-strand RNA virus genomes exert their function in the context of complex replication machineries. Within these replication complexes the polymerase activity is often highly regulated by RNA elements, proteins or other domains of multi-domain polymerases. Here, we present data of the influence of the methyltransferase domain (NS5-MTase) of dengue virus (DENV) protein NS5 on the RdRp activity of the polymerase domain (NS5-Pol). The steady-state polymerase activities of DENV-2 recombinant NS5 and NS5-Pol are compared using different biochemical assays allowing the dissection of the de novo initiation, transition and elongation steps of RNA synthesis. We show that NS5-MTase ensures efficient RdRp activity by stimulating the de novo initiation and the elongation phase. This stimulation is related to a higher affinity of NS5 toward the single-strand RNA template indicating NS5-MTase either completes a high-affinity RNA binding site and/or promotes the correct formation of the template tunnel. Furthermore, the NS5-MTase increases the affinity of the priming nucleotide ATP upon de novo initiation and causes a higher catalytic efficiency of the polymerase upon elongation. The complex stimulation pattern is discussed under the perspective that NS5 adopts several conformations during RNA synthesis.     

Detection of Rickettsia and Anaplasma from hard ticks in Thailand

We collected a total of 169 adult hard ticks and 120 nymphs from under the leaves of plants located along tourist nature trails in ten localities. The results present data examining the vector competence of ticks of different genera and the presence of Rickettsia and Anaplasma species. The ticks belonged to three genera, Amblyomma, Dermacentor, and Haemaphysalis, comprising 11 species. Rickettsia bacteria were detected at three collection sites, while Anaplasma bacteria were detected at only one site. Phylogenetic analysis revealed new rickettsia genotypes from Thailand that were closely related to Rickettsia tamurae, Rickettsia monacensis, and Rickettsia montana. This study was also the first to show that Anaplasma bacteria are found in Haemaphysalis shimoga ticks and are closely related evolutionarily to Anaplasma bovis. These results provide additional information for the geographical distribution of tick species and tick‐borne bacteria in Thailand and can therefore be applied for ecotourism management.     

Horizontal transmission of Rickettsia felis between cat fleas, Ctenocephalides felis

Rickettsia felis is a rickettsial pathogen primarily associated with the cat flea, Ctenocephalides felis. Although laboratory studies have confirmed that R. felis is maintained by transstadial and transovarial transmission in C. felis, distinct mechanisms of horizontal transmission of R. felis among cat fleas are undefined. Based on the inefficient vertical transmission of R. felis by cat fleas and the detection of R. felis in a variety of haematophagous arthropods, we hypothesize that R. felis is horizontally transmitted between cat fleas. Towards testing this hypothesis, flea transmission of R. felis via a bloodmeal was assessed weekly for 4 weeks. Rhodamine B was used to distinguish uninfected recipient and R. felis-infected donor fleas in a rickettsial horizontal transmission bioassay, and quantitative real-time PCR assay was used to measure transmission frequency; immunofluorescence assay also confirmed transmission. Female fleas acquired R. felis infection more readily than male fleas after feeding on a R. felis-infected bloodmeal for 24 h (69.3% and 43.3%, respectively) and both Rickettsia-uninfected recipient male and female fleas became infected with R. felis after cofeeding with R. felis-infected donor fleas (3.3-40.0%). Distinct bioassays were developed to further determine that R. felis was transmitted from R. felis-infected to uninfected fleas during cofeeding and copulation. Vertical transmission of R. felis by infected fleas was not demonstrated in this study. The demonstration of horizontal transmission of R. felis between cat fleas has broad implications for the ecology of R. felis rickettsiosis.     

Molecular Basis for Nucleotide Conservation at the Ends of the Dengue Virus Genome

The dengue virus (DV) is an important human pathogen from the Flavivirus genus, whose genome- and antigenome RNAs start with the strictly conserved sequence pppAG. The RNA-dependent RNA polymerase (RdRp), a product of the NS5 gene, initiates RNA synthesis de novo, i.e., without the use of a pre-existing primer. Very little is known about the mechanism of this de novo initiation and how conservation of the starting adenosine is achieved. The polymerase domain NS5Pol_DV of NS5, upon initiation on viral RNA templates, synthesizes mainly dinucleotide primers that are then elongated in a processive manner. We show here that NS5Pol_DV contains a specific priming site for adenosine 5′-triphosphate as the first transcribed nucleotide. Remarkably, in the absence of any RNA template the enzyme is able to selectively synthesize the dinucleotide pppAG when Mn²⁺ is present as catalytic ion. The T794 to A799 priming loop is essential for initiation and provides at least part of the ATP-specific priming site. The H798 loop residue is of central importance for the ATP-specific initiation step. In addition to ATP selection, NS5Pol_DV ensures the conservation of the 5′-adenosine by strongly discriminating against viral templates containing an erroneous 3′-end nucleotide in the presence of Mg²⁺. In the presence of Mn²⁺, NS5Pol_DV is remarkably able to generate and elongate the correct pppAG primer on these erroneous templates. This can be regarded as a genomic/antigenomic RNA end repair mechanism. These conservational mechanisms, mediated by the polymerase alone, may extend to other RNA virus families having RdRps initiating RNA synthesis de novo.