Translocation of C14-Labeled Assimilates in Squash Petioles

A qualitative analysis of sieve tube sap was undertaken to help determine the method of assimilate movement in phloem. Hydroponically-grown squash plants (Cucurbita melopepo torticollis Bailey) were trimmed to a mature, fully-expanded leaf (the source) and one or more immature, unexpanded leaves (the sinks). The blade of the source leaf was exposed to C14O2 in air for 10 minutes and allowed to translocate for 20 or 50 minutes in ambient air. Petioles of treated leaves were cut into sections and ground in cold buffer with a chilled mortar and pestle to extract materials from the translocation stream. The brei was subjected to differential centrifugations at 121, 3020, 6780, 12100, and 27000 times gravity (g) for 10 minutes. Duplicate 2-ml samples were taken from the supernatant after each centrifugation. The amount of C14 present in each was determined by liquid scintillation counting. Background radiation was determined by analyzing 2-ml samples of buffer. Sugars were extracted from leaf blade and petiole tissue with hot 80% ethanol in a micro-Soxhlet apparatus. Individual sugars were separated by descending paper chromatography. Radioactivity in the several sugars was determined by cutting the chromatograms into 1-cm sections from the origin to the solvent front and eluting each section for 3 hours with distilled water into scintillation vials. C14 was measured as before. Background radiation was determined by elution of chromatographed and unchromatographed paper with distilled water. Because of short translocation times, all C14 detected was assumed to be in the translocation stream. In every case, the amount of C14 was similar in all samples taken from differential centrifugations. These results indicate the presence of the translocate in the slouble portion of the sieve tube sap as opposed to an association with the cell particulate or insoluble portion. C14 in individual sugars was located mainly in the sucrose and stachyose fractions which are known to be translocated in squash. It is concluded that the sugars in squash phloem are found dissolved in the sap of the sieve tubes and not associated with any kind of particulate matter therein, unless the particles were much smaller than mitochondria. These findings would tend to support a mass flow system of assimilate movement rather than one governed by protoplasmic or transcellular streaming

Bagworms and Their Control

Thyridopteryx ephemeraeformis (Haworth) is a serious insect pest of many ornamental shrubs and trees in the eastern half of the United States. This publication outlines its appearance and habits, life cycle, and damage, and describes forms of mechanical, biological, and chemical control

Neonicotinoid Insecticides Alter Induced Defenses and Increase Susceptibility to Spider Mites in Distantly Related Crop Plants

Chemical suppression of arthropod herbivores is the most common approach to plant protection. Insecticides, however, can cause unintended, adverse consequences for non-target organisms. Previous studies focused on the effects of pesticides on target and non-target pests, predatory arthropods, and concomitant ecological disruptions. Little research, however, has focused on the direct effects of insecticides on plants. Here we demonstrate that applications of neonicotinoid insecticides, one of the most important insecticide classes worldwide, suppress expression of important plant defense genes, alter levels of phytohormones involved in plant defense, and decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari: Tetranychidae), in multiple, distantly related crop plants.Using cotton (Gossypium hirsutum), corn (Zea mays) and tomato (Solanum lycopersicum) plants, we show that transcription of phenylalanine ammonia lyase, coenzyme A ligase, trypsin protease inhibitor and chitinase are suppressed and concentrations of the phytohormone OPDA and salicylic acid were altered by neonicotinoid insecticides. Consequently, the population growth of spider mites increased from 30% to over 100% on neonicotinoid-treated plants in the greenhouse and by nearly 200% in the field experiment.Our findings are important because applications of neonicotinoid insecticides have been associated with outbreaks of spider mites in several unrelated plant species. More importantly, this is the first study to document insecticide-mediated disruption of plant defenses and link it to increased population growth of a non-target herbivore. This study adds to growing evidence that bioactive agrochemicals can have unanticipated ecological effects and suggests that the direct effects of insecticides on plant defenses should be considered when the ecological costs of insecticides are evaluated

Genomic Analysis Confirms Population Structure and Identifies Inter-Lineage Hybrids in Aegilops tauschii

Aegilops tauschii, the D-genome donor of bread wheat, Triticum aestivum, is a storehouse of genetic diversity, and an important resource for future wheat improvement. Genomic and population analysis of 549 Ae. tauschii and 103 wheat accessions was performed by using 13,135 high quality SNPs. Population structure, principal component, and cluster analysis confirmed the differentiation of Ae. tauschii into two lineages; lineage 1 (L1) and lineage 2 (L2), the latter being the wheat D-genome donor. Lineage L1 contributes only 2.7% of the total introgression from Ae. tauschii for a set of United States winter wheat lines, confirming the great amount of untapped genetic diversity in L1. Lineage L2 accessions had overall greater allelic diversity and wheat accessions had the least allelic diversity. Both lineages also showed intra-lineage differentiation with L1 being driven by longitudinal gradient and L2 differentiated by altitude. There has previously been little reported on natural hybridization between L1 and L2. We found nine putative inter-lineage hybrids in the population structure analysis, each containing numerous lineage-specific private alleles from both lineages. One hybrid was confirmed as a recombinant inbred between the two lineages, likely artificially post collection. Of the remaining eight putative hybrids, a group of seven from Georgia carry 713 SNPs with private alleles, which points to the possibility of a novel L1–L2 hybrid lineage. To facilitate the use of Ae. tauschii in wheat improvement, a MiniCore consisting of 29 L1 and 11 L2 accessions, has been developed based on genotypic, phenotypic and geographical data. MiniCore reduces the collection size by over 10-fold and captures 84% of the total allelic diversity in the whole collection

Rats bred for low and high running capacity display alterations in peripheral tissues and nerves relevant to neuropathy and pain

IntroductionDiet and activity are recognized as modulators of nervous system disease, including pain. Studies of exercise consistently reveal a benefit on pain. This study focused on female rats to understand differences related to metabolic status and peripheral nerve function in females.MethodsHere, we investigated parameters of peripheral nerve function relevant to pain in rats selectively bred for high (high‐capacity runners; HCR) or low endurance exercise capacity (low‐capacity runners; LCR) resulting in divergent intrinsic aerobic capacities and susceptibility for metabolic conditions.ResultsLCR female rats have reduced mechanical sensitivity, higher intraepidermal nerve fiber density and TrkA‐positive epidermal axons, increased numbers of Langerhans and mast cells in cutaneous tissues, and a higher fat content despite similar overall body weights compared to female HCR rats. Sensory and motor nerve conduction velocities, thermal sensitivity, and mRNA expression of selected genes relevant to peripheral sensation were not different.ConclusionsThese results suggest that aerobic capacity and metabolic status influence sensory sensitivity and aspects of inflammation in peripheral tissues that could lead to poor responses to tissue damage and painful stimuli. The LCR and HCR rats should prove useful as models to assess how the metabolic status impacts pain.These results suggest that aerobic capacity and metabolic status influence sensory sensitivity and aspects of inflammation in peripheral tissues that could lead to poor responses to tissue damage and painful stimuli. The LCR and HCR rats should prove useful as models to assess how the metabolic status impacts pain.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139060/1/brb3780.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139060/2/brb3780_am.pd

Integration of genetic and genomics resources in einkorn wheat enables precision mapping of important traits

Einkorn wheat (Triticum monococcum) is an ancient grain crop and a close relative of the diploid progenitor (T. urartu) of polyploid wheat. It is the only diploid wheat species having both domesticated and wild forms and therefore provides an excellent system to identify domestication genes and genes for traits of interest to utilize in wheat improvement. Here, we leverage genomic advancements for einkorn wheat using an einkorn reference genome assembly combined with skim-sequencing of a large genetic population of 812 recombinant inbred lines (RILs) developed from a cross between a wild and a domesticated T. monococcum accession. We identify 15,919 crossover breakpoints delimited to a median and average interval of 114 Kbp and 219 Kbp, respectively. This high-resolution mapping resource enables us to perform fine-scale mapping of one qualitative (red coleoptile) and one quantitative (spikelet number per spike) trait, resulting in the identification of small physical intervals (400 Kb to 700 Kb) with a limited number of candidate genes. Furthermore, an important domestication locus for brittle rachis is also identified on chromosome 7A. This resource presents an exciting route to perform trait discovery in diploid wheat for agronomically important traits and their further deployment in einkorn as well as tetraploid pasta wheat and hexaploid bread wheat cultivars

The role of genetic factors in otitis media

É sabido que a otite média aguda pode ser causada por fatores ambientais, comofreqüentar creches, fumo passivo, curto período de amamentação e baixas condições sócio-eco-nômicas. A revisão das pesquisas recentes, contudo, sugere que fatores genéticos também contri-buem de forma significativa para a ocorrência da otite média aguda, recorrente e da otite médiacrônica, com efusão. Embora não existam estudos genéticos específicos, há consistentes evidên-cias em favor da transmissão genética de uma suscetibilidade para otite média. A história familiar,características raciais, a freqüência de antígenos HLA e de marcadores genéticos, entre outrosfatores, são algumas das evidências que serão apresentadas nesta revisão de literatura.It is well-known that otitis media can be caused by environmental factors, such asattending day care centers, passive smoking, early interruption of breast feeding, and unfavorablesocio-economic conditions. The review of current literature, however, suggests that genetic factorsalso contribute significantly to the occurrence of recurrent acute otitis media and otitis media witheffusion. Although there are no specific genetic studies, there is consistent evidence to support theidea of genetically transmitted susceptibility to otitis media. Family history, racial characteristics,HLA and genetic marker frequency are some of the topics discussed in the literature, which will bepresented in this review

The role of genetic factors in otitis media

É sabido que a otite média aguda pode ser causada por fatores ambientais, como freqüentar creches, fumo passivo, curto período de amamentação e baixas condições sócio-econômicas. A revisão das pesquisas recentes, contudo, sugere que fatores genéticos também contribuem de forma significativa para a ocorrência da otite média aguda, recorrente e da otite média crônica, com efusão. Embora não existam estudos genéticos específicos, há consistentes evidências em favor da transmissão genética de uma suscetibilidade para otite média. A história familiar, características raciais, a freqüência de antígenos HLA e de marcadores genéticos, entre outros fatores, são algumas das evidências que serão apresentadas nesta revisão de literatura.It is well-known that otitis media can be caused by environmental factors, such as attending day care centers, passive smoking, early interruption of breast feeding, and unfavorable socio-economic conditions. The review of current literature, however, suggests that genetic factors also contribute significantly to the occurrence of recurrent acute otitis media and otitis media with effusion. Although there are no specific genetic studies, there is consistent evidence to support the idea of genetically transmitted susceptibility to otitis media. Family history, racial characteristics, HLA and genetic marker frequency are some of the topics discussed in the literature, which will be presented in this review

An online database for einkorn wheat to aid in gene discovery and functional genomics studies

Diploid A-genome wheat (einkorn wheat) presents a nutrition-rich option as an ancient grain crop and a resource for the improvement of bread wheat against abiotic and biotic stresses. Realizing the importance of this wheat species, reference-level assemblies of two einkorn wheat accessions were generated (wild and domesticated). This work reports an einkorn genome database that provides an interface to the cereals research community to perform comparative genomics, applied genetics and breeding research. It features queries for annotated genes, the use of a recent genome browser release, and the ability to search for sequence alignments using a modern BLAST interface. Other features include a comparison of reference einkorn assemblies with other wheat cultivars through genomic synteny visualization and an alignment visualization tool for BLAST results. Altogether, this resource will help wheat research and breeding. Database URL  https://wheat.pw.usda.gov/GG3/pangenome

Einkorn genomics sheds light on history of the oldest domesticated wheat

Einkorn (Triticum monococcum) was the first domesticated wheat species, and was central to the birth of agriculture and the Neolithic Revolution in the Fertile Crescent around 10,000 years ago$^{1,2}$. Here we generate and analyse 5.2-Gb genome assemblies for wild and domesticated einkorn, including completely assembled centromeres. Einkorn centromeres are highly dynamic, showing evidence of ancient and recent centromere shifts caused by structural rearrangements. Whole-genome sequencing analysis of a diversity panel uncovered the population structure and evolutionary history of einkorn, revealing complex patterns of hybridizations and introgressions after the dispersal of domesticated einkorn from the Fertile Crescent. We also show that around 1% of the modern bread wheat (Triticum aestivum) A subgenome originates from einkorn. These resources and findings highlight the history of einkorn evolution and provide a basis to accelerate the genomics-assisted improvement of einkorn and bread wheat