An Improved Technique for Obtaining Accurate and Precise Morphometric Data on Snakes.

Morphometric measurements are basic but essential data in morphological and ecological research. It is thus beneficial to develop a safe, convenient, multipurpose device/technique to determine body length and physical characteristics of living snakes with high accuracy/precision and low stress, and to enable the probing of snakes and collection of tissue samples. To meet these requirements, we developed an improved technique, which we named the Confining-Box Method (CBM). On measuring the body lengths of a total of 72 live snakes, we found significant differences in the accuracy and precision of measurements among the squeeze-box method, the anesthesia method, and the CBM, as well as between vertebral line and the mid-ventral line measurements. Body lengths, as measured along the vertebral line and corrected for perspective errors, using the CBM, did not differ significantly from the standard lengths measured by hand using anesthesia. The squeeze-box method produced substantial negative bias and/or less precision in ventral measurements, especially for large snakes (> 1.2 m in snout-vent length). The differences between measurers were much smaller than among the different techniques. Compared to the anesthesia technique, CBM is a fast and simple method that is also safer for snakes. Unlike the traditional squeeze-box technique, CBM can record both dorsal and ventral body images of snakes simultaneously and enable researchers to measure accurate and/or precise total length (from dorsal images), tail length (from ventral images), and snout-vent length using images from a single photography session. CBM could therefore become a standard to improve measurement consistency, allowing improved data comparison in future studies.

Elevated risk of hypertension induced by arsenic exposure in Taiwanese rural residents: possible effects of manganese superoxide dismutase (MnSOD) and 8-oxoguanine DNA glycosylase (OGG1) genes.

Heavy metals, including arsenic and lead, may lead to cellular oxidative damage that is linked to hypertension. Manganese superoxide dismutase (MnSOD) is a scavenger of reactive oxygen species, and 8-oxoguanine DNA glycosylase (OGG1) is the major glycosylase that repairs DNA lesions. Interestingly, whether there is an elevated risk of hypertension with arsenic or lead exposure in individuals with genetic variations in MnSOD or OGG1 has not yet been investigated. Questionnaires were administered to 240 Taiwanese rural residents. Blood pressure and biochemical indicators were assessed in each subject. Urinary levels of arsenic and lead were measured with atomic absorption spectrometry; and MnSOD and OGG1 genotypes were identified via polymerase chain reaction. There was a dose-response relationship between urinary arsenic levels and risk of hypertension (P = 0.021, test for trend). However, there was no association between urinary lead levels and hypertension risk. Individuals with high urinary arsenic levels and the MnSOD Val-Ala/Ala-Ala genotypes had a greater risk of hypertension than those with low urinary arsenic levels and the MnSOD Val-Val genotype (odds ratio [OR] = 4.2, 95% confidence interval [CI] = 1.7-10.3). Subjects with a high urinary arsenic level and the OGG1 Cys-Cys genotype also had a greater risk of hypertension than those with a low urinary arsenic level and the OGG1 Ser-Ser/Ser-Cys genotypes (OR = 3.4, 95% CI = 1.1-10.7). Thus, both MnSOD and OGG1 genotypes may be prone to an increased risk of hypertension associated with arsenic exposure.