Singapore's herpetofauna: updated and annotated checklist, history, conservation, and distribution.

Given Singapore's location at the confluence of important maritime trading routes, and that it was established as a British East India Company trading post in 1819, it is unsurprising that Singapore has become one of the centres of natural history collecting and research in Southeast Asia. Despite its small size, Singapore is home to a diverse herpetofauna assemblage and boasts a rich herpetological history. The first systematic studies of Singapore's herpetofauna (within the Linnaean binomial framework) date back to Stamford Raffles and the naturalists hired by him who first came to the island in 1819. Specimens that were collected during and after this time were deposited in museums worldwide. Over time, 39 species from Singapore were described as new to science. Due to the entrepôt nature of Singapore with its associated purchasing and trading of specimens (both alive and dead), poor record-keeping, and human introductions, numerous extraneous species from outside of Singapore were reported to occur on the island. Such issues have left a complicated legacy of ambiguous records and taxonomic complications concerning the identity of Singapore's species-rich herpetofauna, many of which were only resolved in the past 30-40 years. By compiling a comprehensive collection of records and publications relating to the herpetofauna of Singapore, we construct an updated and more accurate listing of the herpetofauna of Singapore. Our investigation culminated in the evaluation of 309 species, in which we compiled a final species checklist recognising 166 species (149 native and 17 non-native established species). Among the 149 native species are two caecilians, 24 frogs, one crocodilian, 13 turtles (three visitors), 34 lizards, and 75 snakes. Of the 17 non-native species are five frogs, four turtles, six lizards, and two snakes. The remaining 143 species represent species to be excluded from Singapore's herpetofauna species checklist. For each of the 309 species examined, we provide species accounts and explanatory annotations. Furthermore, we discuss Singapore's herpetofauna from a historical and conservation perspective. Immediate deforestation and nationwide urbanisation following colonisation completely eliminated many species from throughout much of the country and restricted them to small, degraded forest patches. We hope this publication highlights the importance of publishing observations and serves as a valuable resource to future researchers, naturalists, biological consultants, and policy makers in initiating studies on species ecology, distribution, status, and promoting conservation efforts to safeguard Singapore's herpetofauna.

Neuropathogenesis of HIV and emerging therapeutic targets.

INTRODUCTION: HIV infection causes a wide range of neurological complications, many of which are among the most common complications of chronic HIV infection in the era of combined antiretroviral therapy. These neurological conditions arise due to complex interactions between HIV viral proteins and neuronal and glial cells that lead to the activation of various inflammatory and neurotoxic pathways across the nervous system. AREAS COVERED: This review summarizes the current literature on the pathogenesis and clinical manifestations of neurological injuries associated with HIV in the brain, spinal cord, and peripheral nervous system. Molecular pathways relevant for possible therapeutic targets or advancements are emphasized. Gaps in knowledge and current challenges in therapeutic design are also discussed. EXPERT OPINION: Several challenges exist in the development of therapeutic targets for HIV-associated cognitive impairments. However, recent developments in drug delivery systems and treatment strategies are encouraging. Treatments for HIV-associated pain and peripheral sensory neuropathies currently consist of symptomatic management, but a greater understanding of their pathogenesis can lead to the development of targeted molecular therapies and disease-modifying therapies. HIV-associated autonomic dysfunction may affect the course of systemic disease via disrupted neuro-immune interactions; however, more research is needed to facilitate our understanding of how these processes present clinically.

Structural and functional connections between the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and the immune system: a context and time dependent stress response network.

The autonomic nervous system (ANS), hypothalamic-pituitary-adrenal (HPA) axis, and immune system are connected anatomically and functionally. These three systems coordinate the central and peripheral response to perceived and systemic stress signals. Both the parasympathetic and sympathetic components of the autonomic nervous system rapidly respond to stress signals, while the hypothalamic-pituitary-adrenal axis and immune system have delayed but prolonged actions. In vitro, animal, and human studies have demonstrated consistent anti-inflammatory effects of parasympathetic activity. In contrast, sympathetic activity exerts context-dependent effects on immune signaling and has been associated with both increased and decreased inflammation. The location of sympathetic action, adrenergic receptor subtype, and timing of activity in relation to disease progression all influence the ultimate impact on immune signaling. This article reviews the brain circuitry, peripheral connections, and chemical messengers that enable communication between the ANS, HPA axis, and immune system. We describe findings of in vitro and animal studies that challenge the immune system with lipopolysaccharide. Next, neuroimmune connections in animal models of chronic inflammatory disease are reviewed. Finally, we discuss how a greater understanding of the ANS-HPA-immune network may lead to the development of novel therapeutic strategies that are focused on modulation of the sympathetic and parasympathetic nervous system.

The type species of Bronchocela Kaup, 1827 and lectotype designations for Agama cristatella Kuhl, 1820 and Agama gutturosa Merrem, 1820 (Squamata: Iguania: Agamidae).

The agamid genus Bronchocela Kaup, 1827 comprises 13 species of diurnal, arboreal lizards distributed from India east through Myanmar, Thailand, Cambodia, Vietnam, Malaysia, Singapore, Indonesia, the Philippines, to Papua New Guinea (Diong Lim 1998; Hallermann 2005; Grismer et al. 2015). Once occupying this entire range, B. cristatella's distribution has now been restricted to the Andaman and Nicobar Islands, southern Thailand, Malaysia, Singapore, Indonesia, the Philippines, and Papua New Guinea (Hallermann 2005). My intention here is to: 1) clarify the type species of the genus-group name Bronchocela; 2) resolve the valid name for the taxon under consideration; 3) designate lectotypes for Agama cristatella Kuhl, 1820 and Agama gutturosa Merrem, 1820, and; 4) discuss the type locality for the taxon under consideration.

The original description and date of publication of emCylindrophis/em emlineatus/em and remarks on its type locality (Reptilia: Squamata: Cylindrophiidae).

The snake genus Cylindrophis Wagler, 1828 belongs to the  monogeneric family Cylindrophiidae comprising 15 species distributed predominately throughout SE Asia, with one extralimital species occurring in Sri Lanka (Bernstein et al. 2020: 535). Cylindrophis lineatus is a rare species known from only eight museum specimens (discussed herein), and a photograph of one live individual from Kuching, Sarawak, East Malaysia (Stuebing et al. 2014: 63). Despite being originally described with Singapore as the type-locality (Blanford 1881: 217, 218), it is currently understood that C. lineatus is endemic to western Sarawak, East Malaysia (Stuebing et al. 2014: 63). Wallach et al. (2014: 204) stated that C. lineatus is also found in Kalimantan, but did not provide any references. This appears to have been followed by Bernstein et al. (2020: 537), who provide a map indicating C. lineatus occurrences in Kalimantan. The original description of Cylindrophis lineatus is conventionally cited as Blanford (1881: 217, 218, pl. 20). Herein, we demonstrate that the authorship and date of publication of this taxon should correctly be Cylindrophis lineatus Dennys, 1880b, and discuss that the type locality should be changed to "Borneo".

A Species-Level Phylogeny of Extant Snakes with Description of a New Colubrid Subfamily and Genus.

BACKGROUND: With over 3,500 species encompassing a diverse range of morphologies and ecologies, snakes make up 36% of squamate diversity. Despite several attempts at estimating higher-level snake relationships and numerous assessments of generic- or species-level phylogenies, a large-scale species-level phylogeny solely focusing on snakes has not been completed. Here, we provide the largest-yet estimate of the snake tree of life using maximum likelihood on a supermatrix of 1745 taxa (1652 snake species + 7 outgroup taxa) and 9,523 base pairs from 10 loci (5 nuclear, 5 mitochondrial), including previously unsequenced genera (2) and species (61). RESULTS: Increased taxon sampling resulted in a phylogeny with a new higher-level topology and corroborate many lower-level relationships, strengthened by high nodal support values (> 85%) down to the species level (73.69% of nodes). Although the majority of families and subfamilies were strongly supported as monophyletic with > 88% support values, some families and numerous genera were paraphyletic, primarily due to limited taxon and loci sampling leading to a sparse supermatrix and minimal sequence overlap between some closely-related taxa. With all rogue taxa and incertae sedis species eliminated, higher-level relationships and support values remained relatively unchanged, except in five problematic clades. CONCLUSION: Our analyses resulted in new topologies at higher- and lower-levels; resolved several previous topological issues; established novel paraphyletic affiliations; designated a new subfamily, Ahaetuliinae, for the genera Ahaetulla, Chrysopelea, Dendrelaphis, and Dryophiops; and appointed Hemerophis (Coluber) zebrinus to a new genus, Mopanveldophis. Although we provide insight into some distinguished problematic nodes, at the deeper phylogenetic scale, resolution of these nodes may require sampling of more slowly-evolving nuclear genes.

Image quality produced by different cone-beam computed tomography settings.

INTRODUCTION: The aim of this study was to evaluate image quality at different cone-beam computed tomography settings and 3 fields of view. METHODS: A Hitachi CB MercuRay (Hitachi Medical Systems, Tokyo, Japan) was modified to allow different setting combinations. The variables consisted of 4 milliampere settings (2, 5, 10, and 15 mA), 2 kilovolt (peak) settings (100 and 120 kV[p]), presence or absence of a copper filter, and 3 fields of view (6, 9, and 12 in). Thirty-two scans were taken on a cadaver head and 16 scans on a dry skull. The groups were divided by field of view, and the images were ranked by at least 30 judges. Diagnostic quality was addressed in a questionnaire. Descriptive statistics and rankings were calculated with Excel 2003 (Microsoft, Redmond, Wash) and the Friedman and Wilcoxon signed rank tests with SPSS software (version 14.0.1; SPSS, Chicago, Ill). RESULTS: The presence or absence of a filter showed significant differences (P <.006) in 2 pairs of the 9-in field of view. Variation in kilovolt (peak) settings showed significant differences (P <.006) in the 6-in 5-mA images with a filter. Altering the milliampere settings showed significant differences (P <.008) in the 6- and 12-in groups. The 9-in group showed significant differences between 2 mA and 10 and 15 mA. Overall, the 6-, 9-, and 12-in images had diagnostic quality 56%, 99%, and 99% of the time, respectively. CONCLUSIONS: Presence or absence of a filter and the kilovolt (peak) setting did not affect overall image quality. Images taken at lower milliampere settings showed good diagnostic quality.