ATM activation by DNA double-strand breaks through the Mre11-Rad50-Nbs1 complex

The ataxia-telangiectasia mutated (ATM) kinase signals the presence of DNA double-strand breaks in mammalian cells by phosphorylating proteins that initiate cell-cycle arrest, apoptosis, and DNA repair. We show that the Mre11-Rad50-Nbs1 (MRN) complex acts as a double-strand break sensor for ATM and recruits ATM to broken DNA molecules. Inactive ATM dimers were activated in vitro with DNA in the presence of MRN, leading to phosphorylation of the downstream cellular targets p53 and Chk2. ATM autophosphorylation was not required for monomerization of ATM by MRN. The unwinding of DNA ends by MRN was essential for ATM stimulation, which is consistent with the central role of single-stranded DNA as an evolutionarily conserved signal for DNA damage.     

Diagnostic testing patterns for Streptococcus equi subsp. equi in Ontario horses during the years 2008 to 2018

This retrospective study describes testing patterns and the incidence of Streptococcus equi subsp. equi in Ontario to assess the utility of laboratory data for surveillance purposes. Laboratory records for equine infectious disease test submissions were extracted from the Animal Health Laboratory (AHL) at the University of Guelph for the years 2008 to 2018. Yearly and seasonal trends in S. equi testing and the proportion of tests that returned positive results were assessed. The number of samples submitted for S. equi testing decreased over the 11-year period (odds ratio = 0.96, 95% confidence interval: 0.92 to 0.999; P = 0.04). A generalized linear model identified a significant seasonal effect for animals recognized as clinically ill, with the highest test positivity noted in the winter. Although this study identified important trends in the incidence of S. equi in Ontario, the variability in information accompanying test submissions made the data challenging to interpret, highlighting the need for more complete diagnostic submission data for S. equi.     

Latitudinal differences in the duration of development of Neocalanus plumchrus copepodites

Quasi‐synoptic sampling along a transect from Alaska to California carried out in spring and summer 2000 using Continuous Plankton Recorders reveals that the abundant calanoid copepod Neocalanus plumchrus (Marukawa) reaches the surface at approximately the same time across the region. However, monthly sampling also reveals that the timing of peak biomass (when 50% of the population consists of copepodites at stage CV) occurs about 5 weeks earlier at the southernmost part of its range than at the northernmost part, with intermediate areas having intermediate timings. Surface water temperature differed by about 4°C between the warmer south and the cooler north, and we suggest that such a difference would reduce development duration by about 3 weeks. If food supply in the north is more conducive to lipid accumulation, as seems possible from phytoplankton biomass data, then the use of the differences in timing of peak N. plumchrus biomass in each area as a measure of the differences in development time may not be accurate. We find that the estimate of the time of peak biomass varying by about 5 weeks between north and south may be an exaggeration of the actual difference in the development duration. Temperature is probably the most important factor governing the shorter development duration of N. plumchrus in southern latitudes.     

Impact of lignin structure and cell wall reticulation on maize cell wall degradability

In this study, eight maize recombinant inbred lines were selected to assess both the impact of lignin structure and the impact of cell wall reticulation by p-hydroxycinnamic acids on cell wall degradability independently of the main "lignin content" factor. These recombinant lines and their parents were analyzed for in vitro degradability, cell wall residue content, esterified and etherified p-hydroxycinnamic acid content, and lignin content and structure. Lignin structure and esterified p-coumaric acid content showed significantly high correlation with in vitro degradability (r=-0.82 and r=-0.72, respectively). A multiple regression analysis showed that more than 80% of cell wall degradability variations within these 10 lines (eight recombinant inbred lines and their two parents) were explained by a regression model including two main explanatory factors: lignin content and estimated proportion of syringyl lignin units esterified by p-coumaric acid. This study revealed new biochemical parameters of interest to improve cell wall degradability and promote lignocellulose valorization.     

ALIPOMA OF THE EXTENSOR TENDON SHEATHS IN A HORSE

This report describes the identification and surgical removal of a lipoma from the extensor tendon sheaths of a horse. To the authors' knowledge, this is the first report of a lipoma of the extensor tendon sheaths of a horse. Ultrasonographic evaluation was crucial to patient management, providing information regarding the soft tissue mass characteristics, tumor margins and synovial involvement prior to surgical exploration. Surgical removal was performed and was curative.     

Evaluation of anticollagen type I antibody titers in synovial fluid of both stifle joints and the left shoulder joint of dogs with unilateral cranial cruciate disease

OBJECTIVE: To evaluate anticollagen type I antibodies in synovial fluid of the affected stifle joint, the contralateral stifle joint, and the left shoulder joint of dogs with unilateral cranial cruciate ligament (CrCL) rupture during an extended period of 12 to 18 months. ANIMALS: 13 client-owned dogs with CrCL rupture and 2 sham-operated dogs. PROCEDURES: All dogs were examined and arthrocentesis of all 3 joints was performed every 6 months after surgery. Synovial fluid samples were tested for anticollagen type I antibodies by use of an ELISA. RESULTS: Dogs with partial CrCL rupture had higher antibody titers than dogs with complete rupture. Six of 13 dogs ruptured the contralateral CrCL during the study, whereby higher antibody titers were found for the stifle joints than for the shoulder joint. Seronegative dogs or dogs with extremely low antibody titers and 2 dogs with high antibody titers did not sustain a CrCL rupture in the contralateral stifle joint. CONCLUSIONS AND CLINICAL RELEVANCE: In most dogs that had a CrCL rupture of the contralateral stifle joint, a distinct antibody titer gradient toward the stifle joints was detected, suggesting that there was a local inflammatory process in these joints. However, only a small number of sham-operated dogs were used to calculate the cutoff values used to determine the anticollagen type I antibody titers in these patients. Synovial fluid antibodies against collagen type I alone do not initiate CrCL rupture because not all dogs with high antibody titers sustained a CrCL rupture in the contralateral stifle joint.