Validation of multiple equations for estimating low-density lipoprotein cholesterol levels in Korean adults

Background Limited data are available for validation of low-density lipoprotein cholesterol (LDL) calculation (LDLcal) in the adult Korean population. The aim of this study was to develop and validate a new equation for LDLcal and to compare it with previous such equations in a Korean population. Methods A new equation for LDLcal was developed (LDLChoi). LDLChoi and 11 other previously published equations were applied and compared with directly measured LDL concentration (LDLdirect) in a development cohort (population 1), an independent validation cohort in the same laboratory (population 2), and the Korea National Health and Nutrition Examination Survey 2017 cohort (population 3). Results Among the 12 equations, the newly-developed equation (LDLChoi = total cholesterol – 0.87 x high-density lipoprotein cholesterol – 0.13 x triglycerides) had the highest intraclass correlation coefficient (ICC) and the lowest mean systemic difference and median absolute percentage error in populations 1 and 2 but not in population 3. Subgroup analysis showed good agreement between LDLChoi and LDLdirect (ICC > 0.75) in population 2, whose LDLdirect < 70 mg/dL. For samples with high triglycerides (> 400 mg/dL), equation accuracy varied. Categorization concordance according to the National Cholesterol Education Program Adult Treatment Panel III criteria with the other 11 equations were less than 80%; that of LDLChoi was 87.6 and 87.4% in populations 1 and 2, respectively. Conclusions Accuracy of 12 equations for LDLcal varied by cohort and subgroup based on LDLdirect and triglycerides. A laboratory-specific equation for LDLcal and/or LDLdirect may be needed for accurate evaluation of LDL status.

The importance of individual variation for the interpretation of behavioural studies: ethanol effects vary with basal activity level in zebrafish larvae

Standardization and reduction of variation is key to behavioural screening of animal models in toxicological and pharmacological studies. However, individual variation in behavioural and physiological phenotypes remains in each laboratory population and can undermine the understanding of toxicological and pharmaceutical effects and their underlying mechanisms. Here, we used zebrafish (ABTL-strain) larvae to explore individual consistency in activity level and emergence time, across subsequent days of early development (6–8 dpf). We also explored the correlation between these two behavioural parameters. We found inter-individual consistency over time in activity level and emergence time, but we did not find a consistent correlation between these parameters. Subsequently, we investigated the impact of variation in activity level on the effect of a 1% ethanol treatment, suitable for our proof-of-concept case study about whether impact from pharmacological treatments might be affected by inter-individual variation in basal locomotion. The inter-individual consistency over time in activity level did not persist in this test. This was due to the velocity change from before to after exposure, which turned out to be a dynamic individual trait related to basal activity level: low-activity individuals raised their swimming velocity, while high-activity individuals slowed down, yielding diametrically opposite response patterns to ethanol exposure. We therefore argue that inter-individual consistency in basal activity level, already from 6 dpf, is an important factor to take into account and provides a practical measure to improve the power of statistical analyses and the scope for data interpretation from behavioural screening studies.

Ontogeny of audible squeaks in yellow steppe lemming Eolagurus luteus: trend towards shorter and low-frequency calls is reminiscent of those in ultrasonic vocalization

Background Rodents are thought to be produced their human-audible calls (AUDs, below 20 kHz) with phonation mechanism based on vibration of the vocal folds, whereas their ultrasonic vocalizations (USVs, over 20 kHz) are produced with aerodynamic whistle mechanism. Despite of different production mechanisms, the acoustic parameters (duration and fundamental frequency) of AUDs and USVs change in the same direction along ontogeny in collared lemming Dicrostonyx groenlandicus and fat-tailed gerbil Pachyuromys duprasi. We hypothesize that this unidirectional trend of AUDs and USVs is a common rule in rodents and test whether the AUDs of yellow steppe lemmings Eolagurus luteus would display the same ontogenetic trajectory (towards shorter and low-frequency calls) as their USVs, studied previously in the same laboratory colony. Results We examined for acoustic variables 1200 audible squeaks emitted during 480-s isolation-and-handling procedure by 120 individual yellow steppe lemmings (at 12 age classes from neonates to breeding adults, 10 individuals per age class, up to 10 calls per individual, each individual tested once). We found that the ontogenetic pathway of the audible squeaks, towards shorter and lower frequency calls, was the same as the pathway of USVs revealed during 120-s isolation procedure in a previous study in the same laboratory population. Developmental milestone for the appearance of mature patterns of the squeaks (coinciding with eyes opening at 9–12 days of age), was the same as previously documented for USVs. Similar with ontogeny of USVs, the chevron-like squeaks were prevalent in neonates whereas the squeaks with upward contour were prevalent after the eyes opening. Conclusion This study confirms a hypothesis of common ontogenetic trajectory of call duration and fundamental frequency for AUDs and USVs within species in rodents. This ontogenetic trajectory is not uniform across species.

Biparental age effects in the burying beetle Nicrophorus vespilloides

Parental age at reproduction influences offspring size and survival by affecting prenatal and postnatal conditions in a wide variety of species, including humans. However, most investigations into this manifestation of ageing focus upon maternal age effects; the effects of paternal age and interactions between maternal and paternal age are often neglected. Furthermore, even when maternal age effects are studied, pre- and postnatal effects are confounded. Using a cross-fostered experimental design, we investigated the joint effects of paternal and pre- and postnatal maternal ages on numerous offspring outcomes in a laboratory population of a species of burying beetle, Nicrophorus vespilloides. When we correct our tests for significance for multiple comparisons, we found no clear evidence for any parental effect senescence acting on egg size, larval weight, or larval survival. Nor did we find a statistical effect of paternal or egg producer age on the outcomes of foster mothers as measured by weight change experienced during caregiving. These findings are consistent with recent negative results reported in a similar study of N. vespilloides maternal age effects while also expanding these to other offspring traits and to paternal age effects. We discuss how the peculiar life history of this species may promote selection to resist the evolution of parental age effects, and how this might have influenced our ability to detect senescence.

Detection of Phosphine Resistance in Field Populations of Four Key Stored-Grain Insect Pests in Pakistan

In Pakistan, the control of stored-product insect pests mainly relies on the use of phosphine gas along with other control tactics. The aim of this study was to determine the level of phosphine resistance among ten differently located populations of the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae), the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae). Laboratory-susceptible populations of all insect species were also considered in the experiments. Concentration–response bioassays were conducted for each species. All of the tested populations (10 out of 10) of each species were found to be resistant to phosphine, but varied in their level of resistance. Probit analysis estimated LC50 at 2.85, 1.90, 2.54 and 2.01 ppm for laboratory-susceptible populations of R. dominica, S. granarius, T. castaneum and T. granarium, respectively. Against R. dominica, the highest and lowest resistance levels were observed in the Rahim Yar Khan (LC50 at 360.90 ppm) and Rawalpindi (LC50 at 210.98 ppm) populations, respectively. These resistant populations were 126.67- and 74.02-fold more resistant than the laboratory population. The Multan and Lahore populations of S. granarius exhibited the maximum (LC50 at 122.81 ppm) and minimum (LC50 at 45.96 ppm) resistance levels, respectively, i.e., they were 64.63- and 24.18-fold more resistant than the laboratory population. The Layyah population of T. castaneum showed the maximum resistance level (LC50 at 305.89 ppm) while the lowest was observed in the Lahore population (LC50 at 186.52 ppm), corresponding to 120.42- and 73.43-fold more resistant than the laboratory population, respectively. Regarding T. granarium, the Layyah population showed the maximum resistance level (LC50 at 169.99 ppm) while the Lahore population showed the minimum resistance (LC50 at 74.50 ppm), i.e., they were 84.57- and 37.06-fold more resistant than the laboratory population, respectively. Overall, R. dominica presented the highest resistance level, followed by T. castaneum, T. granarium and S. granarius. The current study suggests that the application of phosphine may not be an adequate control strategy for the management of the above tested insect pests in Pakistan.

Susceptibility of Brazilian Populations of Anastrepha fraterculus, Ceratitis capitata (Diptera: Tephritidae), and Drosophila suzukii (Diptera: Drosophilidae) to Selected Insecticides

Anastrepha fraterculus (Wiedemann), Ceratitis capitata (Wiedemann), and Drosophila suzukii (Matsumura) are the main fruit pests in Brazil. Here, we evaluated the susceptibility of Brazilian populations of A. fraterculus, C. capitata, and D. suzukii to selected insecticides. In ingestion bioassays, adults from a laboratory susceptible population of each species were exposed to five different modes of action of insecticide. Then, field populations of each species were exposed to the diagnostic concentrations to evaluate possible changes in susceptibility. Our findings indicate that lambda-cyhalothrin, malathion, and spinosad had similar levels of toxicity against a susceptible laboratory population of A. fraterculus, with LC50 values of 6.34, 6.54, and 8.76 µg a.i./ml, respectively. Ceratitis capitata had similar susceptibilities to spinosad (1.30 µg a.i./ml), spinetoram (2.76 µg a.i./ml), and malathion (7.10 µg a.i./ml), but a lower susceptibility to lambda-cyhalothrin (76.55 µg a.i./ml). For D. suzukii, the LC50 values of deltamethrin (0.67 µg a.i./ml), malathion (3.30 µg a.i./mL), spinosad (4.16 µg a.i./ml), and spinetoram (4.75 µg a.i./ml) were lower than for abamectin (15.02 µg a.i./ml), acetamiprid (39.38 a.i./ml), and thiamethoxam (70.15 µg a.i./ml). The diagnostic concentrations, based on LC99 values of the insecticides, caused more than 99% mortality for most field populations of each species. For lambda-cyhalothrin the populations RS-1 (A. fraterculus) and SC (C. capitata) showed approximately 10% of live insects. These differences represent the natural variation in population susceptibility and not due to insecticide selection pressure. The diagnostic concentrations defined here should be used in future resistance monitoring programs in Brazil.

A robust, semi-automated approach for counting cementum increments imaged with X-ray computed tomography

Cementum, the tissue attaching mammal tooth roots to the periodontal ligament, grows appositionally throughout life, displaying a series of circum-annual incremental features. These have been studied for decades as a direct record of chronological lifespan. The majority of previous studies on cementum have used traditional thin-section histological methods to image and analyse increments. However, several caveats have been raised in terms of studying cementum increments in thin-sections. Firstly, the limited number of thin-sections and the two-dimensional perspective they impart provide an incomplete interpretation of cementum structure, and studies often struggle or fail to overcome complications in increment patterns that complicate or inhibit increment counting. Increments have been repeatedly shown to both split and coalesce, creating accessory increments that can bias increment counts. Secondly, identification and counting of cementum increments using human vision is subjective, and it has led to inaccurate readings in several experiments studying individuals of known age. Here, we have attempted to optimise a recently introduced imaging modality for cementum imaging; X-ray propagation-based phase-contrast imaging (PPCI). X-ray PPCI was performed for a sample of rhesus macaque ( Macaca mulatta ) lower first molars (n=10) from a laboratory population of known age. A new method for semi-automatic increment counting was then integrated into a purpose-built software package for studying cementum increments. Comparison with data from conventional cementochronology, based on histological examination of tissue sections, confirmed that X-ray PPCI reliably records cementum increments. Validation of the increment counting algorithm suggests that it is robust and provides accurate estimates of increment counts. In summary, we show that our new increment counting method has the potential to overcome caveats of conventional cementochronology approaches, when used to analyse 3D images provided by X-ray PPCI.

On the Reproductive Diapause in the Predatory Ladybird Cheilomenes sexmaculata (Fabricius, 1781) (Coleoptera, Coccinellidae)

The ability to enter reproductive diapause was experimentally studied in females of the laboratory population of the predatory ladybird Cheilomenes sexmaculata originated from individuals collected in Nepal in a region of subtropical monsoon climate. The experiment included 12 regimes, i.e. combinations of 2 temperatures (20 and 24°C), 3 photoperiods (day lengths of 10, 12, and 14 h), and 2 diets (the green peach aphid Myzus persicae and eggs of the grain moth Sitotroga cerealella). Females with undeveloped ovaries and well developed fat body were considered as diapausing. The proportion of diapausing females was significantly dependent only on the temperature being 0.8% at 24°С and 7.4% at 20°С. Although found in only a small fraction of the studied population, the ability to enter reproductive diapause (as suggested by literature data) was probably an important prerequisite for Ch. sexmaculata spread northwards to the temperate zone.

Keeping, Breeding, and Maintenance of Zooculture of the Ladakh Toad, Bufotes latastii (Boulenger, 1882)

In this paper we present results of laboratory reproduction of the Ladakh toad (Bufotes latastii) for three generations. Two pairs of animals, which were collected in April of 2013 in Jammu and Kashmir (India), became founders of a laboratory population. The first female gave offspring four times, while the second only once. The number of eggs in clutches obtained from the first female was 6804 – 10149 and from the second was 4080 eggs. Males, which were born in laboratory, started to vocalize at the age of 3 – 4 months after metamorphosis and at the age of one year successfully reproduced. Females become mature at the two-year age only. Thus, B. latastii is a fast-growing and early-maturing species. The number of eggs in clutches of 2-year-old laboratory females ranged from 31 to 6420 eggs (n = 28) and 3-year-old females from 19 to 6859 eggs (n = 21). Clutches were single- or double-row strings. The average thickness of egg strings was 3.2 – 5.9 mm. The diameter of eggs was 0.8 – 1.9 mm. The duration of embryonic development (until separation of pre-larvae from egg strings) was 2 – 5 days. The total body length of pre-larvae was 2.0 – 4.3 mm. The first larvae that started swimming and feeding were observed within 2 – 3 days after separation of pre-larvae from egg strings. The body length of larvae at the time of start of exogenous feeding was 2.9 – 4.3 mm and the length of tail was 1.6 – 6.3 mm. The total duration of embryogenesis was 4 – 8 days, larval development was 86 – 125 days, and overall development was 90 – 127 days.