Diving into broad-scale and high-resolution population genomics to decipher drivers of structure and climatic vulnerability in a marine invertebrate.

Species with widespread distributions play a crucial role in our understanding of climate change impacts on population structure. In marine species, population structure is often governed by both high connectivity potential and selection across strong environmental gradients. Despite the complexity of factors influencing marine populations, studying species with broad distribution can provide valuable insights into the relative importance of these factors and the consequences of climate-induced alterations across environmental gradients. We used the northern shrimp Pandalus borealis and its wide latitudinal distribution to identify current drivers of population structure and predict the species' vulnerability to climate change. A total of 1514 individuals sampled across 24° latitude were genotyped at high geographic (54 stations) and genetic (14,331 SNPs) resolutions to assess genetic variation and environmental correlations. Four populations were identified in addition to finer substructure associated with local adaptation. Geographic patterns of neutral population structure reflected predominant oceanographic currents, while a significant proportion of the genetic variation was associated with gradients in salinity and temperature. Adaptive landscapes generated using climate projections suggest a larger genomic offset in the southern extent of the P. borealis range, where shrimp had the largest adaptive standing genetic variation. Our genomic results combined with recent observations point to further deterioration in southern regions and an impending vulnerable status in the regions at higher latitudes for P. borealis. They also provide rare insights into the drivers of population structure and climatic vulnerability of a widespread meroplanktonic species, which is crucial to understanding future challenges associated with invertebrates essential to ecosystem functioning.

Eusociality in snapping shrimps is associated with larger genomes and an accumulation of transposable elements.

Despite progress uncovering the genomic underpinnings of sociality, much less is known about how social living affects the genome. In different insect lineages, for example, eusocial species show both positive and negative associations between genome size and structure, highlighting the dynamic nature of the genome. Here, we explore the relationship between sociality and genome architecture in Synalpheus snapping shrimps that exhibit multiple origins of eusociality and extreme interspecific variation in genome size. Our goal is to determine whether eusociality leads to an accumulation of repetitive elements and an increase in genome size, presumably due to reduced effective population sizes resulting from a reproductive division of labor, or whether an initial accumulation of repetitive elements leads to larger genomes and independently promotes the evolution of eusociality through adaptive evolution. Using phylogenetically informed analyses, we find that eusocial species have larger genomes with more transposable elements (TEs) and microsatellite repeats than noneusocial species. Interestingly, different TE subclasses contribute to the accumulation in different species. Phylogenetic path analysis testing alternative causal relationships between sociality and genome architecture is most consistent with the hypothesis that TEs modulate the relationship between sociality and genome architecture. Although eusociality appears to influence TE accumulation, ancestral state reconstruction suggests moderate TE abundances in ancestral species could have fueled the initial transitions to eusociality. Ultimately, we highlight a complex and dynamic relationship between genome and social evolution, demonstrating that sociality can influence the evolution of the genome, likely through changes in demography related to patterns of reproductive skew.

Comparison of remote and in-person respiratory function grading of brachycephalic dogs.

OBJECTIVE: To compare the reliability of respiratory function grading (RFG) scores assigned in-person and remotely via video and electronic stethoscope recordings, evaluated by novice and expert graders. STUDY DESIGN: Prospective study. SAMPLE POPULATION: Fifty-seven brachycephalic dogs. METHODS: Dogs were evaluated in person by expert graders and RFG scores were assigned. Audio and video recordings were made during the in-person evaluations. Four expert and four novice graders evaluated the recordings and assigned an RFG score to each dog. Agreement between in-person and remote RFG scores was assessed using Cohen's kappa statistic. Interobserver reliability was assessed using Fleiss' kappa statistic. RESULTS: The median RFG score from the in-person assessment was 1 (range, 0-3). Distribution of RFG scores included 12 grade 0 scores, 19 grade 1 scores, 25 grade 2 scores, and 1 grade 3 score. The raw percentage agreements between remote and in-person scores were 68.4%, 59.6%, 64.9%, and 61.4% for the four experts, and 52.6%, 64.9%, 50.9%, and 42.1% for the four novices. Reliability between remote and in-person RFG scores was poor to moderate both for the experts (Cohen's kappa: .48, .37, .46, .41) and novices (Cohen's kappa: .28, .47, .28, .21). Interobserver reliability was moderate among the experts (Fleiss' kappa: .59) and poor among the novices (Fleiss' kappa: .39). CONCLUSION: Remote RFG scores had poor to moderate interassessment and interobserver reliability. Novice evaluators performed worse than experts for remote or in-person RFG evaluations. CLINICAL SIGNIFICANCE: Remote RFG, as measured in this study, is not reliable for assigning RFG scores. Modifications could be made to remote evaluation to improve reliability. Based upon the performance of novice evaluators, training of evaluators is justified.

Influence of closed glove exchange on bacterial contamination of the hands of the surgical team.

OBJECTIVE: To determine if closed glove exchange (CGE) increases hand contamination. STUDY DESIGN: Prospective experimental study. SAMPLE POPULATION: Surgical teams participating in 65 individual surgical procedures were included, resulting in 200 individual enrollments. METHODS: At the completion of surgery, gloves were removed and hands were swabbed. The inside of the gown cuff was swabbed. Each participant regloved, using a closed gloving technique. The new gloves were removed, and hands were swabbed for culture a second time. Swabs underwent standard bacterial culture. RESULTS: Before glove exchange, or baseline, contamination was found on 17/200 dominant hands and 13/200 nondominant hands. After performing CGE, contamination was found on 14/200 and 15/200 dominant and nondominant hands, respectively. No difference was detected between the number of CFUs cultured from a surgeon's hands before CGE and the number of CFUs cultured from a surgeon's hands post-CGE (one sided sign test, p = .61). Twelve (12) different bacterial species were identified, the most common were Staphylococcus spp. (97/154; 63%). CONCLUSION: Closed glove exchange did not increase bacterial hand contamination over baseline levels. CLINICAL SIGNIFICANCE: We found no evidence to support discontinuing CGE.

The "Claw Sign" may aid in axial localization in cases of peripherally located canine glioma on MRI.

The "claw sign" is a radiographic sign studied in human imaging to determine if a mass arises from a solid structure or organ versus a close adjacent location, resulting in distortion of the outline of an organ. We investigated its utility in characterizing MRI axial localization of peripherally located intracranial glioma versus meningioma, due to their overlap in MRI appearance. This retrospective, secondary analysis, cross-sectional study aimed to report the sensitivity, specificity, and inter- and intraobserver variabilities using kappa statistics, hypothesizing that the claw sign will have strong inter- and intraobserver agreement (κ > 0.8). Dogs with a histologically confirmed diagnosis of peripherally located glioma or meningioma and available 3T MRI data were retrieved from medical record archives from 2009 to 2021. A total of 27 cases, 11 glioma and 16 meningioma, were included. The postcontrast T1-weighted images were provided to five blinded image evaluators in two separate randomized sessions separated by a 6-week wash out period. Prior to the first evaluation, evaluators were provided with a training video and set of training cases for the "claw sign," which were excluded from the study. Evaluators were asked to rate cases as "positive," "negative," or "indeterminate" for the "claw sign." The sensitivity and specificity for the "claw sign" for the first session were 85.5% and 80%, respectively. The interobserver agreement for identifying the "claw sign" was moderate (κ = 0.48), and the intraobserver agreement across the two sessions was substantial (κ = 0.72). These findings indicate the claw sign is supportive but not pathognomonic for intra-axial localization in cases of canine glioma on MRI.

Tralesinidase Alfa Enzyme Replacement Therapy Prevents Disease Manifestations in a Canine Model of Mucopolysaccharidosis Type IIIB.

Mucopolysaccharidosis type IIIB (MPS IIIB; Sanfilippo syndrome B; OMIM #252920) is a lethal, pediatric, neuropathic, autosomal recessive, and lysosomal storage disease with no approved therapy. Patients are deficient in the activity of N-acetyl-alpha-glucosaminidase (NAGLU; EC 3.2.150), necessary for normal lysosomal degradation of the glycosaminoglycan heparan sulfate (HS). Tralesinidase alfa (TA), a fusion protein comprised of recombinant human NAGLU and a modified human insulin-like growth factor 2, is in development as an enzyme replacement therapy that is administered via intracerebroventricular (ICV) infusion, thus circumventing the blood brain barrier. Previous studies have confirmed ICV infusion results in widespread distribution of TA throughout the brains of mice and nonhuman primates. We assessed the long-term tolerability, pharmacology, and clinical efficacy of TA in a canine model of MPS IIIB over a 20-month study. Long-term administration of TA was well tolerated as compared with administration of vehicle. TA was widely distributed across brain regions, which was confirmed in a follow-up 8-week pharmacokinetic/pharmacodynamic study. MPS IIIB dogs treated for up to 20 months had near-normal levels of HS and nonreducing ends of HS in cerebrospinal fluid and central nervous system (CNS) tissues. TA-treated MPS IIIB dogs performed better on cognitive tests and had improved CNS pathology and decreased cerebellar volume loss relative to vehicle-treated MPS IIIB dogs. These findings demonstrate the ability of TA to prevent or limit the biochemical, pathologic, and cognitive manifestations of canine MPS IIIB disease, thus providing support of its potential long-term tolerability and efficacy in MPS IIIB subjects. SIGNIFICANCE STATEMENT: This work illustrates the efficacy and tolerability of tralesinidase alfa as a potential therapeutic for patients with mucopolysaccharidosis type IIIB (MPS IIIB) by documenting that administration to the central nervous system of MPS IIIB dogs prevents the accumulation of disease-associated glycosaminoglycans in lysosomes, hepatomegaly, cerebellar atrophy, and cognitive decline.

Modeling demersal fish and benthic invertebrate assemblages in support of marine conservation planning.

Marine classification schemes based on abiotic surrogates often inform regional marine conservation planning in lieu of detailed biological data. However, these schemes may poorly represent ecologically relevant biological patterns required for effective design and management strategies. We used a community-level modeling approach to characterize and delineate representative mesoscale (tens to thousands of kilometers) assemblages of demersal fish and benthic invertebrates in the Northwest Atlantic. Hierarchical clustering of species occurrence data from four regional annual multispecies trawl surveys revealed three to six groupings (predominant assemblage types) in each survey region, broadly associated with geomorphic and oceanographic features. Indicator analyses identified 3-34 emblematic taxa of each assemblage type. Random forest classifications accurately predicted assemblage distributions from environmental covariates (AUC > 0.95) and identified thermal limits (annual minimum and maximum bottom temperatures) as important predictors of distribution in each region. Using forecasted oceanographic conditions for the year 2075 and a regional classification model, we projected assemblage distributions in the southernmost bioregion (Scotian Shelf-Bay of Fundy) under a high emissions climate scenario (RCP 8.5). Range expansions to the northeast are projected for assemblages associated with warmer and shallower waters of the Western Scotian Shelf over the 21st century as thermal habitat on the relatively cooler Eastern Scotian Shelf becomes more favorable. Community-level modeling provides a biotic-informed approach for identifying broadscale ecological structure required for the design and management of ecologically coherent, representative, well-connected networks of Marine Protected Areas. When combined with oceanographic forecasts, this modeling approach provides a spatial tool for assessing sensitivity and resilience to climate change, which can improve conservation planning, monitoring, and adaptive management.

Comparison of median sternotomy closure-related complication rates using orthopedic wire or suture in dogs: A multi-institutional observational treatment effect analysis.

OBJECTIVE: To determine and compare median sternotomy (MS) closure-related complication rates using orthopedic wire or suture in dogs. STUDY DESIGN: Multi-institutional, retrospective observational study with treatment effect analysis. ANIMALS: 331 client-owned dogs, of which 68 were excluded. METHODS: Medical records of dogs with MS were examined across nine referral centers (2004-2020). Signalment, weight, clinical presentation, surgical details, complications, and outcomes were recorded. Follow-up was performed using patient records and email/telephone contact. Descriptive statistics, treatment effect analysis and logistic regression were performed. RESULTS: Median sternotomy closure was performed with wire in 115 dogs and suture in 148. Thirty-seven dogs experienced closure-related complications (14.1%), 20 in the wire group and 17 in the suture group. Twenty-three were listed as mild, four as moderate and 10 as severe. Treatment effect analysis showed a mean of 2.3% reduction in closure-related complications associated with using suture versus wire (95% CI: -9.1% to +4.5%). In multivariable logistic regression, the only factor associated with increased risk of closure-related complications was dog size (p = .01). This effect was not modified by the type of closure used (interaction term: OR = 0.99 [95% CI: 0.96/1.01]). CONCLUSION: The incidence of closure-related complication after MS was low compared to previous reports. The likelihood of developing a closure-related complication was equivalent between sutures and wires, independent of dog size, despite a higher proportion of complications seen in larger dogs (≥20 kg). CLINICAL SIGNIFICANCE: Use of either orthopedic wire or suture appear to be an appropriate closure method for sternotomy in dogs of any size.

The impact of a surgical checklist on surgical outcomes in an academic institution.

OBJECTIVE: To determine the influence of a surgical checklist (SC) on morbidities and compliance with safety measures. STUDY DESIGN: Before-and-after-intervention study. SAMPLE POPULATION: Three thousand two hundred eighty-six dogs: 1375 dogs pre-SC and 1911 post-SC. METHODS: Completion of safety measures and occurrence of morbidity and/or mortality during hospitalization and up to death or 30-days postoperatively were recorded. RESULTS: Safety measures were more frequently completed post-SC, including oral confirmation of patient identity (467/1177 [40%] vs. 1911/1911 [100%]) and oral confirmation of surgical site (568/1175 [48%] vs. 1911/1911 [100%]). In addition, duration of anesthesia decreased from 241 to 232 min (t = 2.824; p = .005); a greater proportion of animals that were intended to receive antibiotics did so prior to incision (1142/1316 [86.8%] vs. 1656/1845 [89.8%] [χ2 = 6.70, p = .01]); and fewer dogs had unplanned return to the OR (32/1065 [3.0%], vs. 21/1472 [1.4%]) (χ2 = 7.52, p = .006). No difference in surgical site infection (adjusted odds ratio 1.02 [95%CI: 0.63-1.66]); morbidity, (adjusted odds ratio 1.00 [95%CI: 0.77-1.29]); or death within 30 days (adjusted odds ratio 1.15 [95%CI: 0.72-1.83]) was detected on multivariable logistic regression analysis. The checklist prevented one wrong-site surgery. CONCLUSION: Implementation of the checklist at our institution led to a decrease in anesthesia duration, increased administration of planned perioperative antibiotics before incision, increased completion of safety measures, and decreased unexpected return to the OR. IMPACT: Despite the lack of effect on morbidities, the use of SC is recommended to improve compliance with safety measures and potentially prevent rare catastrophic events.

Correlations between age, body size, sex, and conformation and ultrasound-measured femoral vessel diameter in the dog, with implications for transvascular procedural planning.

Transvascular interventional radiology procedures have advanced in veterinary medicine, but basic knowledge about expected vascular size and vascular imaging requires further exploration. A prospective analytical study of 230 client-owned dogs was carried out to investigate correlations between ultrasound-measured femoral artery (FA) and femoral vein (FV) diameter and various morphometric and demographic dog variables, compare ultrasound-measured femoral vessel diameter to diameter predicted by body weight, compare right- and left-sided femoral vessel diameter, and assess measurement repeatability. Internal diameter of the FA and FV was measured with ultrasound bilaterally. Allometrically scaled body weight had the strongest correlation with FA and FV diameter (correlation coefficients: 0.92 and 0.80, respectively), although thigh circumference (FA: 0.89; FV:0.78) and withers height (FA: 0.84; FV: 0.76) were also strongly correlated. Within the entire population, males had a smaller FA (P = .005), but not FV (P = .278), than females and age was negatively associated with FA (P = .031) and FV (P < .001) diameter. Compared to ultrasound-derived measurements, body weight-predicted diameter overestimated by at least one French gauge in 32.6% and 35.2% of dogs for the FA and FV, respectively. Comparison of left and right FA and FV diameter revealed minimal mean differences, though limits of agreement could encompass multiple French gauge sizes: (Mean difference [limits of agreement]: FA = 0.00 mm [0.85-0.84 mm]; FV = 0.04 mm [1.92-1.99 mm]). Intra- and interoperator repeatability coefficients of variation were <9%. Femoral vessel diameter in dogs is influenced by multiple factors, with potential for clinically relevant differences between right- and left-sided vessels. Ultrasound measurement of femoral vessels could improve transvascular preprocedural planning.

Verminous myelopathy secondary to aberrant Dirofilaria immitis migrans was detected in the cervical subarachnoid space of four dogs using MRI and CT.

Aberrant Dirofilaria immitis migrans is a rare cause of neurologic signs in dogs, however, published studies describing the computed tomographic (CT) and magnetic resonance imaging (MRI) characteristics of this problem are currently lacking. The objective of this retrospective case series study was to describe the clinical and imaging findings for four adult dogs with verminous myelopathy due to aberrant Dirofilaria immitis migrans within the cervical subarachnoid space. All dogs were toy breeds, were heartworm antigen positive, had neurologic signs (ranging from cervical hyperesthesia to tetraparesis), and similar MRI findings. In two patients additionally imaged with CT, findings were variable. On MRI, each dog had a single large, dorsal- to laterally located, intradural-extramedullary, fusiform mass with characteristic stippled, mixed T2-weighted and T1-weighted signal intensity, hypo-to-iso T1-weighted signal intensity, and spinal cord compression. Nematodes were identified as serpentine or circular subarachnoid structures with low T2-weighted and T1-weighted signal in the sagittal and transverse image planes, respectively. CT (n = 2 dogs) demonstrated focal regions of mildly enhancing intradural-extramedullary spinal cord compression in 1 dog. Dorsal laminectomy and durotomy were performed in two dogs at C3-C4. A C4-5 hemilaminectomy with durotomy and dural biopsy was performed in one dog. Extraction of live, immature adult, female D. immitis worms was performed in three dogs. Operated dogs had complete post-surgical resolution of clinical signs. One dog was euthanized without surgery; necropsy revealed an adult heartworm in the spinal subarachnoid space at C2. Findings indicated that cervical spinal subarachnoid D. immitis aberrant migration should be considered as a differential diagnosis for dogs with this combination of clinical and CT/MRI imaging findings, and that the prognosis may be good with early detection and surgical removal.

CEREBROSPINAL FLUID SAMPLING IN A BOTTLENOSE DOLPHIN (TURSIOPS TRUNCATUS) UNDER GENERAL ANESTHESIA.

Brucella ceti, associated with neurobrucellosis, has been isolated from cerebrospinal fluid (CSF) of postmortem cetaceans. A 106-kg, stranded female bottlenose dolphin (Tursiops truncatus) presented with serum antibodies to Brucella spp. via competitive enzyme-linked immunosorbent assay and fluorescence polarization assay. Polymerase chain reaction (PCR) and culture of whole blood, bronchoalveolar fluid, and rectal, nasal, and genital swabs for Brucella spp. were consistently negative. Serial computed tomography revealed mild focal dilatation of brain ventricles. CSF sampling was warranted to exclude neurobrucellosis. Sedation was achieved with 30 mg diazepam (0.28 mg/kg) orally 2.5 hours prior to arrival in hospital, followed by 5.3 mg midazolam (0.05 mg/kg) intramuscularly, and anesthetic induction with 2.5 mg midazolam (0.02 mg/kg) and 200 mg propofol (2 mg/kg) administered slowly intravenously, followed by intubation and maintenance on sevoflurane using controlled mechanical and apneustic anesthesia ventilation. The atlanto-occipital joint was opened by flexing the upper cervical region with the animal in left lateral recumbency. A 20-ga × 6-inch spinal needle was advanced into the cisterna magna using radiographic guidance. CSF was collected successfully with no neurological deficits appreciable on recovery. Brucella spp. was not identified via PCR or culture. This represents the first report of an antemortem CSF tap in a cetacean.

Fine-scale temperature-associated genetic structure between inshore and offshore populations of sea scallop (Placopecten magellanicus).

In the northwest Atlantic Ocean, sea scallop (Placopecten magellanicus) has been characterized by a latitudinal genetic cline with a breakpoint between northern and southern genetic clusters occurring at ~45°N along eastern Nova Scotia, Canada. Using 96 diagnostic single-nucleotide polymorphisms (SNPs) capable of discriminating between northern and southern clusters, we examined fine-scale genetic structure of scallops among 27 sample locations, spanning the largest geographic range evaluated in this species to date (~37-51°N). Here, we confirmed previous observations of northern and southern groups, but we show that the boundary between northern and southern clusters is not a discrete latitudinal break. Instead, at latitudes near the previously described boundary, we found unexpected patterns of fine-scale genetic structure occurring between inshore and offshore sites. Scallops from offshore sites, including St. Pierre Bank and the eastern Scotian Shelf, clustered with southern stocks, whereas inshore sites at similar latitudes clustered with northern stocks. Our analyses revealed significant genetic divergence across small spatial scales (i.e., 129-221 km distances), and that spatial structure over large and fine scales was strongly associated with temperature during seasonal periods of thermal minima. Clear temperature differences between inshore and offshore locations may explain the fine-scale structuring observed, such as why southern lineages of scallop occur at higher latitudes in deeper, warmer offshore waters. Our study supports growing evidence that fine-scale population structure in marine species is common, often environmentally associated, and that consideration of environmental and genomic data can significantly enhance the identification of marine diversity and management units.

Surgical intervention for vertebral osteomyelitis in a calf.

OBJECTIVE: To report the surgical treatment and outcome of a non-ambulatory calf with cervical vertebral ostoeomyelitis. STUDY DESIGN: Clinical report. SAMPLE POPULATION: One 3.5-month-old female mixed-breed calf with tetraparesis of 3 months duration. METHODS: After computed tomography-guided bone biopsy, a bacterial osteolytic lesion within the body of the fourth cervical vertebrae (C4) and resultant pathologic compression fracture clinically resulting in full tetraparesis was diagnosed in the calf. Culture results from the lesion within C4 confirmed a diagnosis of Trueperella pyogenes. RESULTS: Poor response to medical management justified surgical debridment of the lesion in C4 and subsequent stabilization of the cervical vertebral column. A three-part procedure was performed including (1) debridement of the C4, (2) bilateral ventral vertebral stabilization from C3 to C5, and (3) placement of ampicillin-impregnated plaster of Paris beads within the body of C4. With postoperative physical rehabilitation, the calf regained full ambulatory function. At 1-month follow-up, the calf remained ambulatory with mild proprioceptive ataxia and no evidence of implant failure. At annual recheck, the calf had gained 208 kg and remained fully ambulatory with no residual neurologic deficits. CONCLUSION: Surgical intervention and use of antibiotic-impregnated implants offered a viable alternative to long-term medical management of vertebral osteomyelitis in the calf reported here. CLINICAL SIGNIFICANCE: This case identifies surgical intervention as a potential means for improving outcomes in a historically fatal condition of production animals.

A Wearable Body Controlling Device for Application of Functional Electrical Stimulation.

In this research, we describe a new balancing device used to stabilize the rear quarters of a patient dog with spinal cord injuries. Our approach uses inertial measurement sensing and direct leg actuation to lay a foundation for eventual muscle control by means of direct functional electrical stimulation (FES). During this phase of development, we designed and built a mechanical test-bed to develop the control and stimulation algorithms before we use the device on our animal subjects. We designed the bionic test-bed to mimic the typical walking gait of a dog and use it to develop and test the functionality of the balancing device for stabilization of patient dogs with hindquarter paralysis. We present analysis for various muscle stimulation and balancing strategies, and our device can be used by veterinarians to tailor the stimulation strength and temporal distribution for any individual patient dog. We develop stabilizing muscle stimulation strategies using the robotic test-bed to enhance walking stability. We present experimental results using the bionic test-bed to demonstrate that the balancing device can provide an effective sensing strategy and deliver the required motion control commands for stabilizing an actual dog with a spinal cord injury.

Nuclear DNA content correlates with depth, body size, and diversification rate in amphipod crustaceans from ancient Lake Baikal, Russia.

Lake Baikal in Russia is a large, ancient lake that has been the site of a major radiation of amphipod crustaceans. Nearly 400 named species are known in this single lake, and it is thought that many more await description. The size and depth of Lake Baikal, in particular, may have contributed to the radiation of endemic amphipods by providing a large number of microhabitats for species to invade and subsequently experience reproductive isolation. Here we investigate the possibility that large-scale genomic changes have also accompanied diversification in these crustaceans. Specifically, we report genome size estimates for 36 species of Baikal amphipods, and examine the relationship between genome size, body size, and the maximum depths at which the amphipods are found in the lake. Genome sizes ranged nearly 8-fold in this sample of amphipod species, from 2.15 to 16.63 pg, and there were significant, positive, phylogenetically corrected relationships between genome size, body size, maximum depth, and diversification rate among these species. Our results suggest that major genomic changes, including transposable element proliferation, have accompanied speciation that was driven by selection for differences in body size and habitat preference in Lake Baikal amphipods.

The Genome Sizes of Ostracod Crustaceans Correlate with Body Size and Evolutionary History, but not Environment.

Within animals, a positive correlation between genome size and body size has been detected in several taxa but not in others, such that it remains unknown how pervasive this pattern may be. Here, we provide another example of a positive relationship in a group of crustaceans whose genome sizes have not previously been investigated. We analyze genome size estimates for 46 species across the 2 most diverse orders of Class Ostracoda, commonly known as seed shrimps, including 29 new estimates made using Feulgen image analysis densitometry and flow cytometry. Genome sizes in this group range ~80-fold, a level of variability that is otherwise not seen in crustaceans with the exception of some malacostracan orders. We find a strong positive correlation between genome size and body size across all species, including after phylogenetic correction. We additionally detect evidence of XX/XO sex determination in 3 species of marine ostracods where male and female genome sizes were estimated. On average, genome sizes are larger but less variable in Order Myodocopida than in Order Podocopida, and marine ostracods have larger genomes than freshwater species, but this appears to be explained by phylogenetic inertia. The relationship between phylogeny, genome size, body size, and habitat is complex in this system and provides a baseline for future studies examining the interactions of these biological traits.

Patterns of genome size variation in snapping shrimp.

Although crustaceans vary extensively in genome size, little is known about how genome size may affect the ecology and evolution of species in this diverse group, in part due to the lack of large genome size datasets. Here we investigate interspecific, intraspecific, and intracolony variation in genome size in 39 species of Synalpheus shrimps, representing one of the largest genome size datasets for a single genus within crustaceans. We find that genome size ranges approximately 4-fold across Synalpheus with little phylogenetic signal, and is not related to body size. In a subset of these species, genome size is related to chromosome size, but not to chromosome number, suggesting that despite large genomes, these species are not polyploid. Interestingly, there appears to be 35% intraspecific genome size variation in Synalpheus idios among geographic regions, and up to 30% variation in Synalpheus duffyi genome size within the same colony.

Genome size estimates for crustaceans using Feulgen image analysis densitometry of ethanol-preserved tissues.

Crustaceans are enormously diverse both phylogenetically and ecologically, but they remain substantially underrepresented in the existing genome size database. An expansion of this dataset could be facilitated if it were possible to obtain genome size estimates from ethanol-preserved specimens. In this study, two tests were performed in order to assess the reliability of genome size data generated using preserved material. First, the results of estimates based on flash-frozen versus ethanol-preserved material were compared across 37 species of crustaceans that differ widely in genome size. Second, a comparison was made of specimens from a single species that had been stored in ethanol for 1-14 years. In both cases, the use of gill tissue in Feulgen image analysis densitometry proved to be a very viable approach. This finding is of direct relevance to both new studies of field-collected crustaceans as well as potential studies based on existing collections.

Electrocardiographic abnormalities are associated with seropositive Trypanosoma cruzi infection status using a simplified cardiac diagnostic evaluation in dogs.

OBJECTIVE: To describe associations between cardiac abnormalities and Trypanosoma cruzi serostatus by use of a simplified diagnostic evaluation in dogs at risk for T cruzi infection. METHODS: A prospective, cross-sectional study was performed using a simplified diagnostic evaluation including high-sensitivity cardiac troponin I, 30-second ECG, and echocardiogram with 7 variables in 46 client-owned dogs from high-risk environments. Dogs were categorized as serologically positive (SP), negative (SN), or discordant (SD) by use of 2 antibody tests. Functional evaluation of cardiac health scores and blood PCR were obtained. RESULTS: Dogs were SP (n = 19), SN (17), and SD (10), with 9 PCR positive (7 SP, 1 SN, 1 SD). Troponin was above reference range in 6 of 46 (4 SP, 1 SN, 1 SD), and functional evaluation of cardiac health scores were 0 in all dogs. Conduction system abnormalities (prolonged interval durations, second-degree atrioventricular block, splintered QRS complex) and ventricular arrhythmias were documented in 8 (7 SP, 0 SN, 1 SD). Twenty-six (12 SP, 8 SN, 6 SD) had echocardiographic abnormalities, most often myxomatous mitral valve disease (MMVD) and left ventricular enlargement. Seropositive dogs were significantly older and had a higher likelihood of MMVD. Conduction system abnormalities were associated with positive serostatus. CONCLUSIONS: Echocardiographic abnormalities were complicated by MMVD and did not distinguish between serostatus. An ECG with assessment and detailed measurement of complexes and cardiac troponin I are simple tests to perform with abnormalities detected in seroreactive dogs. CLINICAL RELEVANCE: Electrocardiographic abnormalities in high-risk or seroreactive dogs should prompt further evaluation and monitoring of T cruzi infection.