Whole-tree water balance and indicators for short-term drought stress in non-bearing ‘Barnea’ olives

Drainage-weighing lysimeters allowed monitoring of water balance components of non-bearing olive (Olea europaea cv Barnea) trees over a 3-month period including short-term events of controlled but severe water stress. The objective of the study was to evaluate a variety of soil and plant-based water status and drought stress monitoring methods on the basis of tree-scale evapotranspiration (ET). As the trees entered into and recovered from water stress, meteorological data, actual ET (ET_a), soil water content and changes in leaf turgor pressure were continuously monitored. Additionally, midday measurements of stem water potential, stomatal conductance, canopy temperature, and quantum yield of PSII photochemistry were conducted. Diurnal (dawn to dusk) measurements of all the above were made hourly on days of maximum stress. Shoot elongation rate was measured for periods of stress and recovery. Quantum yield of PSII photochemistry, stomatal conductance, and stem water potential all successfully indicated reductions in whole-tree water consumption beginning at moderate stress levels. These measured parameters fully recovered to the levels of non-stressed trees soon after water application was renewed. Shoot elongation was reduced 25-30% for the 10-day period during and following drought and recovered thereafter to levels of non-stressed trees. Whole-tree ET_a was reduced by as much as 20% even following full recovery of the leaf level parameters, suggesting reduced canopy size and growth due to the stress period. Non-destructive, continuous (turgor pressure) and remotely sensed (canopy temperature) methods showed promising potential for monitoring effects of water stress, in spite of technological and data interpretation challenges requiring further attention.     

Vagococcus salmoninarum I—A chronic coldwater streptococcosis in broodstock brook trout (Salvelinus fontinalis) in Wisconsin,USA

In 2018, Vagococcus salmoninarum was isolated from two lots of broodstock “coaster” brook trout (Salvelinus fontinalis) containing ~1,500 fish at the Iron River National Fish Hatchery, at which time it was identified as the causative agent of a chronic coldwater streptococcosis epizootic. Clinical signs included exophthalmia, lethargy, erratic swimming and loss of equilibrium. Female fish experienced disproportionately higher morbidity and mortality than male co-inhabitants, and routinely retained eggs following spawning. The most consistent gross clinical sign was heart pallor and turbid pericardial effusion. An attempted treatment using florfenicol was ineffective at halting the epizootic, which spanned more than a year and resulted in >50% mortality before remaining fish were culled. As there is no previous documentation of V. salmoninarum at this hatchery or in this species, it is still unclear what circumstances led to this epizootic. The inability to treat this chronic disease led to the loss of valuable broodstock, hampering ongoing fishery conservation efforts in the Great Lakes Basin.     

Vagococcus salmoninarum II—qPCR,tropism and egg-associated transmission

Vagococcus salmoninarum was identified as the causative agent of a chronic epizootic in broodstock “coaster” brook trout (Salvelinus fontinalis) at the Iron River National Fish Hatchery. The epizootic spanned more than a year, was unresponsive to multiple florfenicol treatments, and resulted in >50% mortality of the affected fish. The decision was made to cull the remaining fish during spawning, which presented an opportunity to more thoroughly examine V. salmoninarum sampling methods, organ tropism and vertical transmission. A newly developed qPCR targeting the pheS gene was used in concert with bacterial culture to show that V. salmoninarum indeed disproportionately affects females and has a tropism for female reproductive tissues. The study demonstrates that some female reproductive tissues (e.g. ovarian fluid, unfertilized eggs) are also an effective option for non-lethal detection. Despite the widespread presence of V. salmoninarum in ovarian fluid and on egg surfaces, we found no evidence of intra-ova transmission.     

First detection and isolation of infectious haematopoietic necrosis virus from farmed rainbow trout in Nyeri County,Kenya

Infectious haematopoietic necrosis virus (IHNV) is the causative agent of infectious haematopoietic necrosis, a disease of salmonid responsible for great economic losses. The disease occurs in most parts of the world where rainbow trout is reared but has not been previously reported in Kenya. In this study, rainbow trout fry and growers from two farms in Nyeri County were screened for IHNV. Whole fry (n = 4 from each farm) and kidney samples from growers (n = 15 and n = 6 from the two farms, respectively) were collected and preserved for cell culture examination or PCR analysis. Screening of samples was done by PCR followed by sequencing of the glycoprotein gene of the virus. Demonstration of the virus was done by propagation in EPC cells followed by the indirect fluorescence antibody test (IFAT). The results revealed the presence of IHNV at low prevalence of 0.1 and 0.4 for the two farms. The virus was confirmed both by IFAT and by partial sequencing of the G gene. Phylogenetic analysis revealed that the Kenyan isolates were identical to those of the J genogroup found mostly in Asia. The findings have implications for biosecurity measures and import regulations for the Kenyan rainbow trout industry.     

Genome-wide association analysis of resistance to Pythium ultimum in common bean (Phaseolus vulgaris)

Pythium root rot (PRR) caused by Pythium spp. is an important root rot disease affecting common bean productivity. The objective of this study was to conduct a genome-wide association analysis of resistance to PRR in the common bean of Andean gene pool using single nucleotide polymorphism (SNP) markers. About 260 genotypes of the Andean diversity panel (ADP) were evaluated under screen house conditions using Pythium ultimum isolate MS61 in Uganda. Sixteen significant signals for resistance to PRR were detected on chromosomes Pv01, Pv02, Pv04, Pv05 and Pv09 using 260K GBS-based and 6K Beadchip SNPs. Common significant signals were detected on Pv02 and Pv09 for PRR. Positional candidate genes associated with significant SNPs on Pv02 were Phvul.002G119700, 16.97 kb near marker S02_25507837 (25.50 Mb), encoding Subtilase family protein, and Phvul.002G278400 near marker ss715645959 (44.79 Mb) encoding Defensin-like (DEFL) protein involved in plant defence responses. Based on the relatively high heritability estimates observed for PRR in this study, significant SNP markers associated with genomic regions for resistance to PRR could be validated for marker-assisted breeding in Andean beans.     

Seasonal variation in the condition index of Pacific oyster postlarvae (Crassostrea gigas) in a land‐based nursery in Sonora,Mexico

This study examined the seasonal variation in the condition index (CI) of Crassostrea gigas postlarvae (<5 mm) that were cultivated at a commercial hatchery. Oysters were sampled weekly at the nursery using seawater from a lagoon for the grow‐out that precedes commercialization. Temperature, salinity, seston, chlorophyll a, oxygen and pH were recorded at each sampling and water samples were taken to identify phytoplankton groups and their abundance. High levels of primary productivity, chlorophyll a and seston were detected during summer, but the highest CI occurred in winter. During winter, elevated phytoplankton biomass was composed by diatoms and phytoflagellates, which served as the main food source and promoted weight gain in this season. Variations in salinity, oxygen and pH were not related to differences in the CI. However, it appears that the wide temperature variation affected functions, such as feeding activity, apparently enhancing ingestion during winter (mean 16.5±1.4 °C) and reducing ingestion during summer (mean 31±1.5 °C). Winter production resulted in postlarvae with a homogeneous size range and a high CI, indicating that winter is more favourable to start cultivation. The CI represents a practical means to determine the physiological state of postlarvae before transfer to cultivation sites.     

Pyrethroid synergism by esterase inhibition in Spodoptera littoralis (Boisduval) larvae

The susceptibility of cotton leafworm, Spodoptera littoralis (Boisduval) larvae to poisoning by trans-permethrin and cis-cypermethrin was increased when these pyrethroids were applied topically after the larvae had ingested profenofos, monocrotophos or azinphos-methyl for 24 h. An ingested dose of 4 nmol profenofos per larva gave a synergism factor of about threefold for both trans-permethrin and cis-cypermethrin. These pyrethroids were not synergized by oxidase inhibitors such as piperonyl butoxide, SV-1 and MPP ingested at 80 nmol/larva. Esterase preparations of larval gut hydrolysed trans-permethrin two to three times more rapidly than cis-permethrin, deltamethrin, trans- or cis-cypermethrin. Integument esterase(s) are less active but show a similar preference for trans-permethrin. The gut esterase(s) hydrolysing trans-permethrin are more sensitive in vitro and in vivo to inhibition by profenofos than by azinphos-methyl or monocrotophos. The susceptibility of S. littoralis larvae to pyrethroids appears to be limited by pyrethroid esterases in the gut. Organophosphorous compounds inhibiting these detoxifying enzymes serve as synergists.     

Fish catches among riverside communities around Lago Grande de Monte Alegre,Lower Amazon,Brazil

Forty‐six families living around the Amazon floodplain lake of Lago Grande de Monte Alegre, Brazil, were monitored between April 1993 and March 1995 with respect to their fish catches. The average catch per fisherman was 22 kg day^‐1. There were significant differences between subsistence and commercial fishing, and also across different seasons of the year. Catch was higher in the dry season and in the lake environment, followed by the river environment. The flooded forest was exploited in the rainy season. Out of a total of more than 70 fish species, 10 taxa comprised 75% of the catch. The catch in the Monte Alegre region concentrated on smaller species for local consumption. Prochilodus nigricans (Spix & Agassiz) was the most important species, followed by Liposarcus pardalis (Castelnau) and Plagioscion spp. Comparisons between quantities of fish consumed and fish marketed indicated that the fishery has a much more important role in the region than previously thought.     

BRCT repeats as phosphopeptide-binding modules involved in protein targeting

We used a proteomic approach to identify phosphopeptide-binding modules mediating signal transduction events in the DNA damage response pathway. Using a library of partially degenerate phosphopeptides, we identified tandem BRCT (BRCA1 carboxyl-terminal) domains in PTIP (Pax transactivation domain-interacting protein) and in BRCA1 as phosphoserine- or phosphothreonine-specific binding modules that recognize substrates phosphorylated by the kinases ATM (ataxia telangiectasia-mutated) and ATR (ataxia telangiectasia- and RAD3-related) in response to gamma-irradiation. PTIP tandem BRCT domains are responsible for phosphorylation-dependent protein localization into 53BP1- and phospho-H2AX (gamma-H2AX)-containing nuclear foci, a marker of DNA damage. These findings provide a molecular basis for BRCT domain function in the DNA damage response and may help to explain why the BRCA1 BRCT domain mutation Met1775 --> Arg, which fails to bind phosphopeptides, predisposes women to breast and ovarian cancer.