Seasonal variation and an “outbreak” of frog predation by tamarins

We report temporal variation and an “outbreak” of frog predation by moustached tamarins, Saguinus mystax, in north-eastern Peruvian Amazonia. Frog predation rates were generally very low, but strongly increased in October 2015. Other high rates, identified by outlier analyses, were also observed in September–November of other years. Over all study years, predation rates in this 3-month period were significantly higher than those in the remainder of the year, suggesting a seasonal pattern of frog predation by tamarins. Reduced fruit availability or increased frog abundance or a combination of both may be responsible for both the seasonal pattern and the specific “outbreak” of frog predation.     

Novel insights into the genetic background of genetically modified mice

Unclear or misclassified genetic background of laboratory rodents or a lack of strain awareness causes a number of difficulties in performing or reproducing scientific experiments. Until now, genetic differentiation between strains and substrains of inbred mice has been a challenge. We have developed a screening method for analyzing inbred strains regarding their genetic background. It is based on 240 highly informative short tandem repeat (STR) markers covering the 19 autosomes as well as X and Y chromosomes. Combination of analysis results for presence of known C57BL/6 substrain-specific mutations together with autosomal STR markers and the Y-chromosomal STR-haplotype provides a comprehensive snapshot of the genetic background of mice. In this study, the genetic background of 72 mouse lines obtained from 18 scientific institutions in Germany and Austria was determined. By analyzing only 3 individuals per genetically modified line it was possible to detect mixed genetic backgrounds frequently. In several lines presence of a mispairing Y chromosome was detected. At least every second genetically modified line displayed a mixed genetic background which could lead to unexpected and non-reproducible results, irrespective of the investigated gene of interest.     

Numerical investigation of bone remodelling around immediately loaded dental implants using sika deer (Cervus nippon) antlers as implant bed

This study combines finite element method and animal studies, aiming to investigate tissue remodelling processes around dental implants inserted into sika deer antler and to develop an alternative animal consuming model for studying bone remodelling around implants. Implants were inserted in the antlers and loaded immediately via a self-developed loading device. After 3, 4, 5 and 6 weeks, implants and surrounding tissue were taken out. Specimens were scanned by μCT scanner and finite element models were generated. Immediate loading and osseointegration conditions were simulated at the implant-tissue interface. A vertical force of 10 N was applied on the implant. During the healing time, density and Young’s modulus of antler tissue around the implant increased significantly. For each time point, the values of displacement, stresses and strains in the osseointegration model were lower than those of the immediate loading model. As the healing time increased, the displacement of implants was reduced. The 3-week immediate loading model (9878 ± 1965 μstrain) illustrated the highest strains in the antler tissue. Antler tissue showed similar biomechanical properties as human bone in investigating the bone remodelling around implants, therefore the use of sika deer antler model is a promising alternative in implant biomechanical studies.     

A novel model to characterize structure and function of BRCA1

BRCA1 plays a central role in DNA repair. Although N‐terminal RING and C‐terminal BRCT domains are studied well, the functions of the central region of BRCA1 are poorly characterized. Here, we report a structural and functional analysis of BRCA1 alleles and functional human BRCA1 in chicken B‐lymphocyte cell line DT40. The combination of “homologous recombineering” and “RT‐cassette” enables modifications of chicken BRCA1 gene in Escherichia coli. Mutant BRCA1 knock‐in DT40 cell lines were generated using BRCA1 mutation constructs by homologous recombination with a targeting efficiency of up to 100%. Our study demonstrated that deletion of motifs 2–9 BRCA1^{Δ/Δ181‐1415} (Caenorhabditis elegans BRCA1 mimic) or deletion of motif 1 BRCA1^{Δ/Δ126‐136} decreased cell viability following cisplatin treatment. Furthermore, deletion of motifs 5 and 6 BRCA1^{Δ/Δ525‐881} within DNA‐binding region, even the conserved 7‐amino acid deletion BRCA1^{Δ/Δ872‐878} within motif 6, caused a decreased cell viability upon cisplatin treatment. Surprisingly, human BRCA1 is functional in DT40 cells as indicated by DNA damage‐induced Rad 51 foci formation in human BRCA1 knock‐in DT40 cells. These results demonstrate that those conserved motifs within the central region are essential for DNA repair functions of BRCA1. These findings provide a valuable tool for the development of new therapeutic modalities of breast cancer linked to BRCA1.     

Effects of scarcity and excess of larval food on life history traits of Aedes aegypti (Diptera: Culicidae)

Few studies have assessed the effects of food scarcity or excess on the life history traits of Aedes aegypti (L.) (Diptera: Culicidae) independently from larval density. We assessed immature survival, development time, and adult size in relation to food availability. We reared cohorts of 30 Ae. aegypti larvae from newly hatched to adult emergence with different food availability. Food conditions were kept constant by transferring larvae each day to a new food solution. Immature development was completed by some individuals in all treatments. The shortest development time, the largest adults, and the highest survival were observed at intermediate food levels. The most important effects of food scarcity were an extension in development time, a decrease in the size of adults, and a slight decrease in survival, while the most important effects of food excess were an important decrease in survival and a slight decrease in the size of adults. The variability in development time and adult size within sex and treatment increased at decreasing food availability. The results suggest that although the studied population has adapted to a wide range of food availabilities, both scarcity and excess of food have important negative impacts on fitness.     

Documenting Resistance and Physiological Changes in Soybean Challenged by <Emphasis Type="Italic">Aphis glycines</Emphasis> Matsumura (Hemiptera: Aphididae)

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a limiting factor in soybean production in the North Central region of the USA. The objectives of this work were to identify sources of resistance to A. glycines in 14 soybean genotypes, and also document changes in total protein, peroxidase, and chlorophyll in response to aphid feeding. A reduced number of A. glycines was observed on the genotypes UX 2569-159-2-01 and UX 2570-171- 04, indicating the presence of antixenosis and/or antibiosis. UX 2569-159-2-01 expressed the highest level of resistance; whereas, UX 2570-171-04 had moderate levels of resistance to A. glycines. Chlorophyll content was relatively unaffected by A. glycines, except for a reduction in UX 2569-159-2-01 infested plants at 5 and 15 days after infestation (DAI). No changes were detected in total protein content between infested and control plants for the genotypes analyzed; however, peroxidase activity was higher in infested UX 2570-171-04 at both 5 and 10 DAI. This improvement in peroxidase content in infested UX 2570-171-04 may be playing multiple roles in the plant tolerance.     

Characterization of estrous cycles and pregnancy in Somali wild asses (Equus africanus somaliensis) through fecal hormone analyses

Although reproduction in the domestic horse has been well described, less is known about reproduction in wild equids. This study describes endocrine patterns associated with estrous cycles and pregnancy for Somali wild asses (Equus africanus somaliensis), an endangered African equid. Fecal samples were collected three times per week for more than 2 years from five female Somali wild asses at the Saint Louis Zoo; progestagen and estrogen metabolites were quantified using commercially available immunoassays. Progestagen analysis indicated that cycle lengths were 27.2 ± 1.2 days and females cycled throughout the year. Progestagen levels during early pregnancy were low and not sustained above baseline until approximately 40 weeks prior to partition. Concentrations increased markedly around 16 weeks prior to delivery and peaked 2–3 weeks before birth. Fecal estrogen levels also increased significantly starting 40–45 weeks before parturition and reached their maximal value approximately 20 weeks prior to birth. Neither foal heat nor lactational suppression of estrus was observed, and females cycled within 45 days after delivery. These data are the first to describe the reproductive physiology of Somali wild asses. As the species faces increasing threats in the wild, this information may support conservation efforts by assisting with ex situ breeding programs.