Trends and change points in surface and bottom thermal environments of the US Northeast Continental Shelf Ecosystem

Temperature is an important factor in defining the habitats of marine resource species. While satellite sensors operationally measure ocean surface temperatures, we depend on in situ measurements to characterize benthic habitats. Ship‐based measurements were interpolated to develop a time series of gridded spring and fall, surface and bottom temperature fields for the US Northeast Shelf. Surface and bottom temperatures have increased over the study period (1968–2018) at rates between 0.18–0.31°C per decade and over a shorter time period (2004–2018) at rates between 0.26–1.49°C per decade. A change point analysis suggests that a warming regime began in the surface waters in 2011 centered on Georges Bank and the Nantucket Shoals; in following years, most of the Northeast Shelf had experienced a shift in surface temperature. A similar analysis of bottom temperature suggests a warming regime began in 2008 in the eastern Gulf of Maine; in following years, change points in temperature occurred further to the west in the Gulf of Maine, finally reaching the Middle Atlantic Bight by 2010. The spatial pattern in bottom water warming is consistent with well‐known oceanographic patterns that advect warming North Atlantic waters into the Gulf of Maine. The varying spatial and temporal progression of warming in the two layers suggests they were actuated by different sets of forcing factors. We then compared these trends and change points to responses of lower and higher trophic level organisms and identified a number of coincident shifts in distribution and biomass of key forage and fisheries species.     

Natural products in agriculture—a view from the industry

The paper discusses the use of natural products and biological control agents in crop protection from an industrial viewpoint. The criteria which must be satisfied are noted. Examples are given from the genetic engineering of baculoviruses and proteins. The final section considers the utility of natural products as a source of leads for conventional agrochemicals, and the screens needed. © 1998 SCI.     

The Breed and Season Effects on Scrotal Circumference and Semen Characteristics of Hair Sheep Rams Under Tropical Conditions

The aim of the present work was to evaluate the breed and season effects on scrotal circumference (SC) and semen characteristics of 28 mature hair sheep rams kept under tropical conditions. SCs, sperm concentration (SPC) and abnormal sperm were significantly affected by breed effect (p < 0.001). The season effect was significant in SPC (p < 0.0001) while ejaculate volume, mass motility and SPC were affected by breed × season interaction effect (p < 0.001). It can be concluded that the magnitude of the breed and season effects were not sufficient to affect the reproductive capacity of hair sheep rams throughout the year.     

Characteristics and comparative performance of direct culture, direct PCR and enumeration methods for detection and quantification of Campylobacter spp. in broiler caeca

Detection and enumeration of Campylobacter spp. in broiler chicken flocks are key components of research and surveillance studies aimed at reducing Campylobacter infections in people. Direct culture of caecal contents onto selective agar is the typical method used to confirm flock colonisation. Modified charcoal cefoperazone deoxycholate agar (mCCDA) is commonly used for this method, although alternative selective media have been used. Additionally, PCR methods to detect Campylobacter DNA from caecal contents may provide a rapid alternative. However comparative performance data for these methods is limited and therefore required to ensure optimal detection methods for this sample type. In this study, 306 broiler caeca were tested for Campylobacter using direct culture on mCCDA, Skirrows and Preston agars and two real-time PCR methods, one specific for mapA/ceuE regions and another for the flaA gene region. Additionally, the suitability of spread plating and spiral plating methods for enumeration of Campylobacter and the impact of sample storage were assessed. This study confirmed modified CCDA as an optimal media for detection of Campylobacter in broiler caeca. It was significantly more sensitive than Skirrows or Preston agars. This study also demonstrated that the mapA/ceuE PCR had excellent agreement with culture on mCCDA and is a genuine alternative method. Spread plating and spiral plating methods were suitable for enumeration although spiral plating appeared more sensitive for stored samples (72h). A 1 log reduction in viable Campylobacters was observed in stored samples, therefore storage effects should be considered for quantitative studies with broiler caeca.     

Low-field standing magnetic resonance imaging findings of the metacarpo/metatarsophalangeal joint of racing Thoroughbreds with lameness localised to the region: a retrospective study of 131 horses

Reasons for performing study: The metacarpo/metatarsophalangeal (MCP/MTP) joint is a common site of lameness in the Thoroughbred racehorse. Radiographs may fail to show pathology consistent with the degree of lameness. With a high incidence of stress fractures occurring in the distal third metacarpal/metatarsal (MC3/MT3) condyles and proximal phalanx, a definitive diagnosis as to the nature of the pathology is essential. Objective: To describe the low‐field magnetic resonance imaging (MRI) findings in Thoroughbred racehorses with MCP/MTP joint pain scanned under standing sedation. Methods: The MR images and clinical records of all Thoroughbred racehorses undergoing MRI of the MCP/MTP joint between October 2006 and August 2010 were reviewed. A total of 168 joints from 131 horses were selected for inclusion. The MRI finding considered most significant in the lame (or lamest) limb was noted. Results: Diagnostic quality images were obtainable in 97.8% of horses. The most common finding was palmar/plantar osteochondral disease in MC3/MT3 (54.9% of horses). Incomplete condylar fracture was diagnosed in 19.8% of horses, with the lateral condyle predominating. An incomplete sagittal fracure of P1 was diagnosed in 14.5% of horses and 11.4% were diagnosed with ‘dorsal joint disease’. Other findings included transverse MC3 stress fractures (1.5%), soft tissue injuries (12.2%) and proximal phalangeal ‘contusions’ (3.8%). No significant bone/soft tissue injury was detected in 5.4% of cases. Conclusions: Standing MRI can detect a spectrum of disease within the MCP/MTP joints of racehorses. The procedure is well tolerated and may lead to a definitive diagnosis where radiographic imaging is inconclusive. Potential relevance: A total of 35.8% of cases had MRI findings consistent with fracture pathology, which could not be confirmed radiographically at the time of the MRI examination. This has important therapeutic and prognostic implications and may help to prevent catastrophic injury.     

A graft-based chemotherapy method for screening effective molecules and rescuing huanglongbing-affected citrus plants

Huanglongbing (HLB) is the most devastating disease of citrus. The global citrus industry is in urgent need of effective chemical treatments for HLB control because of its rapid spreading worldwide. Due to the fastidious nature of the pathogens, and the poor permissibility of citrus leaf surfaces, effective screening of chemicals for the HLB control can be challenging. In this study, we developed a graft-based chemotherapy method to rapidly screen potential HLB-controlling chemical compounds. In addition, we improved transmission efficiency by using the best HLB-affected scion-rootstock combination, and demonstrated the HLB bacterial titer was the critical factor in transmission. The HLB-affected lemon scions had a high titer of HLB bacterium, survival rate (83.3%), and pathogen transmission rate (59.9%). Trifoliate, a widely used commercial rootstock, had the highest survival rate (>70.0%) compared with grapefruit (52.6%) and sour orange (50.4%). Using this method, we confirmed a mixture of penicillin and streptomycin was the most effective compounds in eliminating the HLB bacterium from the HLB-affected scions, and in successfully rescuing severely HLB-affected citrus germplasms. These findings are useful not only for chemical treatments but also for graft-based transmission studies in HLB and other Liberibacter diseases.     

Whole body net ion fluxes, plasma electrolyte concentrations and haematology during a Loma salmonae infection in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum)

Loma salmonae infections of salmonids culminate in the development of branchial xenomas and subsequent focal hyperplasia of the lamellar or filament epithelium following xenoma rupture and spore release. The effects of this acute branchial disruption upon net ionic flux rates and plasma electrolyte concentrations were determined in juvenile rainbow trout given an experimental oral exposure to L. salmonae. Mean numbers of branchial xenomas peaked at week 5 post-exposure (PE), which coincided with a reduction in the specific growth rate, although there were no significant differences in mass, length or condition of Loma-exposed fish compared with unexposed controls. Following exposure, negative net whole body Na(+) and K(+) fluxes decreased, whereas net Cl(-) fluxes remained unchanged compared with non-exposed control fish. At week 3 PE during the initial branchial xenoma formation stage, there was a significant negative whole body net K(+) flux in Loma-exposed trout compared with other points during the exposure and subsequent infection. Additionally, Loma-exposed fish had marginally elevated plasma Na(+) and Cl(-) concentrations, whilst K(+) levels remained unchanged, compared with control fish. Although there was a progressive decrease in leucocrit, haematocrit remained unchanged over the course of the Loma exposure and subsequent infection. These results suggest that ionic compensation can occur at the gills during the development of xenomas during exposure to L. salmonae and the resultant infection, therefore allowing defence of plasma electrolyte concentrations, unlike the acute ionic disturbances seen with some other parasitic diseases.