An ion-pair reversed-phase HPLC method for determination of fresh tissue adenine nucleotides avoiding freeze-thaw degradation of ATP

Knowledge of the energetic state of tissue is required in a wide range of experimental studies, particularly those investigating the decline and recovery of cellular metabolism after metabolic stress. Such information can be obtained from high-performance liquid chromatography (HPLC) determination of tissue levels of adenine nucleotides (ATP, ADP, and AMP) and their interrelationship in the tissue energy charge (EC). Accordingly, a large range of techniques with which to measure these molecules and their downstream metabolites have been reported. However, the accurate determination of the tissue EC also depends on the nucleotide extraction procedure given that changes in adenine nucleotide levels take place very quickly when ATPases are not inactivated immediately. In this article, we describe an ion-pair reversed-phase HPLC method by which separation of adenine nucleotides can be performed rapidly, allowing multiple analyses in 1 day, with both high sensitivity and extraction efficiency and using fresh samples, thereby avoiding freeze-thaw degradation of nucleotides. We applied this method to hippocampal brain slice extracts and show that same-day extraction and analysis results in a more accurate determination of the in situ energetic state than does the commonly used snap-freezing in liquid nitrogen.     

Camera Trap Observations of Nonhabituated Critically Endangered Wild Blonde Capuchins,Sapajus flavius (Formerly Cebus flavius)

Habituation presents major challenges for the study of wild primates, particularly in areas where threats such as hunting pressure and increasing forest fragmentation exist. This study describes the use of ground camera trapping to investigate nonhabituated blonde capuchins. Capuchins are arboreal animals, but often use the ground when foraging. Thus, we hypothesized that a ground-baited camera trapping station would be an efficient method to document the presence of capuchins, and to collect information about aspects of their social behavior and ecology. We conducted 92 systematic trapping days over 15 months (from December 2010 to February 2011 and from August 2011 to July 2012). The capuchins visited the trapping stations 43 times. All visits occurred between 05:13h and 17:32h, and lasted 3 min-2:03 h. Sixty-five percent of the photographs included our target species. Groups contained up to 46 individuals and were multimale-multifemale. We recorded no monkeys at the trapping stations during August and November (2011) and January (2012). Infants were more likely to be carried than not. Infants were carried by both sexes; however, 96% of photographs showed females as carriers. Adult males always arrived first at the camera trapping stations, suggesting that males led the group’s movements. The ground-baited camera trapping stations proved effective for confirming the presence of the blonde capuchins in the study site and for documenting aspects of their social behavior. The technique could potentially be used to provide comparative data among populations of this and other primate species in areas where habituation is difficult or risky to the primates.     

Diphacinone with cholecalciferol for controlling possums and ship rats

ABSTRACT

Potent second-generation anticoagulant rodenticides such as brodifacoum have been used as more effective alternatives to first-generation anticoagulants, such as warfarin. A combination of diphacinone at 0.005% and cholecalciferol at 0.06% produces a slow-acting bait that is effective at killing possums (Trichosurus vulpecula) and rodents. Cage trials with groups of possums and ship rats (Rattus rattus) achieved a mortality of 87% and 86% for possums and ship rats, respectively. Two field trials, each 200 hectares in size, targeting possums, ship rats and mice achieved an average reduction in the abundance of 94% for possums, 94% for ship rats and 80% for mice. The combination of diphacinone and cholecalciferol appears effective and has a favourable risk profile compared with second-generation anticoagulant rodenticides, such as brodifacoum. Approval of this new bait by the New Zealand Environmental Protection Agency was granted in 2018 and final registration obtained from the Ministry of Primary Industries in 2019.     

Molecular weight and amino acid composition of purified spinach beet phenolase

The purification of spinach beet phenolase has been modified to include equilibration of the crude macerate with 0.5% cetyl-trimethylammonium bromide a     

Comparison of urinary aflatoxin M1 and aflatoxin albumin adducts as biomarkers for assessing aflatoxin exposure in Tanzanian children

Purpose: To determine levels of urinary aflatoxin M1 (AFM1) in children and correlate the concentrations with previously reported aflatoxin albumin adduct (AF-alb) levels in these children.

Materials and methods: Matched urine and blood samples were collected from 84 Tanzanian children aged 6–14 months old. From 31 children in one village (Kigwa), samples were collected at three time points six months apart. Samples were collected from 31 and 22 children from two different regions at the second time point only. Urinary AFM1 was measured using a commercial enzyme-linked immunosorbent assay (ELISA) kit with a modified protocol to improve sensitivity. AF-alb was measured using an established ELISA method.

Results: The relative ranking of the three villages for exposure to aflatoxin based on either AFM₁ or AF-alb biomarker measurements was the same. In Kigwa village, both AFM1 and AF-alb levels were higher at six months post-harvest compared to baseline. However, at the next visit, the AFM1 levels dropped from a GM (interquartile range) of 71.0 (44.7, 112.6) at visit two to 49.3 (31.5, 77.3) pg/ml urine, whereas AF-alb levels increased from 47.3 (29.7, 75.2) to 52.7 (35.4, 78.3) pg/mg albumin between these two visits, reflecting the fact that AFM1 measures short-term exposure, whereas AF-alb measures longer term exposure. There was a correlation between AFB1 intake and AFM1 excretion (r=?0.442, p?≤?0.001).

Conclusions: Urinary AFM1 is a good biomarker for AFB1 exposure in Tanzanian children, reflecting geographical and temporal variations in exposure to this foodborne toxin.     

Different ecological conditions support individual specialization in closely related,ecologically similar species

Individual generalist predators often have more specialized diets than their populations do. Individual specialization (IS) is influenced by ecological opportunity, intraspecific competition, and interspecific competition, although the effects of these parameters are inconsistent across studies. We investigated IS in five species of frogs and toads, Anaxyrus americanus, A. fowleri, Lithobates catesbeianus, L. clamitans, and L. sphenocephalus. We used the natural history and ecology of each species to predict which parameters would influence IS. Our predictions were supported for some species but not others. We predicted IS would be positively influenced by resource diversity in all species, but this prediction held for only three species, with the relationship significant in A. fowleri and L. catesbeianus and marginally significant in A. americanus. We also predicted that interspecific competition would have a negative relationship with IS in L. clamitans because L. catesbeianus is competitively superior to L. clamitans and likely to suppress its foraging options. This prediction was upheld. Finally, we predicted that IS in A. americanus, A. fowleri, and L. clamitans would be influenced by intraspecific competition. However, IS was not influenced by intraspecific competition in any species, a surprising result given that intraspecific competition has traditionally been assumed to be the ecological parameter with the strongest effects on IS. Many previous studies did not simultaneously consider all three ecological parameters, which may have increased the apparent importance of intraspecific competition for IS. Our results revealed that the ecological parameters affected IS differently even across closely related and ecologically similar species, and demonstrated that these differences are sometimes predictable based on natural history. This study also suggests that sympatric ecological speciation based on IS may be rare because the ecological parameters driving IS are inconsistent across species, and the strength of their effects on intraspecific diet variation varies in space.