In vitro selection for 2,4-D tolerance in red clover

Summary In vitro, selection is a viable method of selecting herbicide-tolerant crops. This research was to evaluate in vitro selection techniques for enhancing 2,4-D [(2,4-dichlorophenoxy) acetic acid] tolerance in red clover (Trifolium pratense L.). In vivo and in vitro responses to 2,4-D of eight diverse red clover populations were correlated (r=0.77), justifying in vitro selection for 2,4-D tolerance. Suspension cultures of a red clover genotype capable of regeneration were plated onto agar-based nutrient media supplemented with 0.18 mM 2,4-D for selection experiments. After two cycles of selection, 16 2,4-D tolerant callus lines were identified based on visual growth assessment. These lines were evaluated for 2,4-D tolerance (based on 2,4-D content), using a 2,4-D bioassay procedure which consisted of placing selected callus tissue pieces on top of oat (Avena sativa L.) coleoptile or internode sections. The relative amount of 2,4-D in the callus tissue was estimated by the amount of oat section elongation after 24 h. Two of the more tolerant callus lines had 61% and 83% less 2,4-D in their tissues than the susceptible control tissue. These studies indicated that in vitro selection can enhance the levels of 2,4-D tolerance in red clover callus tissue.Florida Agricultural Experiment Station Journal Series No. 8943     

Brightness contrast effects in monkey lateral geniculate nucleus.

Brightness contrast effects shown by single cells in the macaque's lateral geniculate nucleus were studied with black and white lines of various widths, consisting of either: (1) "simultaneous contrast" stimuli in which the line was produced by luminance changes in the flanking areas or (2) "successive contrast" stimuli in which the line itself changed in luminance. Line widths that gave optimal responses and response magnitudes themselves were similar for the two types of stimulus, except for the widest lines used (2 degrees). Thus, simultaneous brightness contrast is a primary determinant of the response of primate LGN cells but only within 2 degrees of the center of the receptive field. Neural processing up to this level cannot therefore explain the long distance effects of simultaneous brightness contrast in human perception.     

Differentiation in life cycle of sympatric populations of two forms of Hyphantria moth in central Missouri

Wing patterns of Hyphantria adult male moths collected in central Missouri were examined throughout the breeding season. Three major peaks of adult flight were observed: the first peak consisted mainly of adults with spotted wings, while the second and third peaks consisted of immaculate adults. Black‐headed larvae appeared in the field following the first major peak of moth flight, and red‐headed larvae appeared in the field following the second peak. Sympatric red‐headed and black‐headed forms were collected in the field and subsequently reared on an artificial diet under conditions of 16 h light : 8 h dark (LD 16:8) at 25°C. The larval period of the black‐headed form was shorter than the red‐headed, whereas the pupal period of the black‐headed form was longer than the red‐headed. Pupal development is retarded in some individuals at high temperatures in the black‐headed form. Photoperiodic response curves for pupal diapause were different between the two forms. The critical photoperiod for pupal diapause was 15 h 10 min in the red‐headed form, which was longer than that for the black‐headed form (14 h 40 min). The two forms responded to shifts in photoperiod differently. These developmental responses temporally separate the two forms in the field; the red‐headed and black‐headed forms represent a set of adaptations favoring univoltinism and bivoltinism, respectively. Red‐headed larvae fed mainly at night, while the black‐headed larvae fed without a clear day–night rhythm. Nocturnal feeding in the red‐headed form is adaptive to protection against predation, but fails to fully utilize heat units and thus to produce a second generation.     

Numerosity estimation in visual stimuli in the absence of luminance-based cues

Background

Numerosity estimation is a basic preverbal ability that humans share with many animal species and that is believed to be foundational of numeracy skills.It is notoriously difficult, however, to establish whether numerosity estimation is based on numerosity itself, or on one or more non-numerical cues like—in visual stimuli—spatial extent and density. Frequently, different non-numerical cues are held constant on different trials. This strategy, however, still allows numerosity estimation to be based on a combination of non-numerical cues rather than on any particular one by itself.

Methodology/Principal Findings

Here we introduce a novel method, based on second-order (contrast-based) visual motion, to create stimuli that exclude all first-order (luminance-based) cues to numerosity. We show that numerosities can be estimated almost as well in second-order motion as in first-order motion.

Conclusions/Significance

The results show that numerosity estimation need not be based on first-order spatial filtering, first-order density perception, or any other processing of luminance-based cues to numerosity. Our method can be used as an effective tool to control non-numerical variables in studies of numerosity estimation.     

A higher order motion region in human inferior parietal lobule: evidence from fMRI

The proposal that motion is processed by multiple mechanisms in the human brain has received little anatomical support so far. Here, we compared higher- and lower-level motion processing in the human brain using functional magnetic resonance imaging. We observed activation of an inferior parietal lobule (IPL) motion region by isoluminant red-green gratings when saliency of one color was increased and by long-range apparent motion at 7 Hz but not 2 Hz. This higher order motion region represents the entire visual field, while traditional motion regions predominantly process contralateral motion. Our results suggest that there are two motion-processing systems in the human brain: a contralateral lower-level luminance-based system, extending from hMT/V5+ into dorsal IPS and STS, and a bilateral higher-level saliency-based system in IPL.     

Ecological thresholds: Concept,Methods and research outlooks

The concept of ecological thresholds was raised in the 1970s. However, it was subsequently given different definitions and interpretations depending on research fields or disciplines. For most scientists, ecological thresholds refer to the points or zones that link abrupt changes between alternative stable states of an ecosystem. The measurement and quantification of ecological thresholds have great theoretical and practical significance in ecological research for clarifying the structure and function of ecosystems, for planning sustainable development modes, and for delimiting ecological red lines in managing the ecosystems of a region. By reviewing the existing concepts and classifications of ecological thresholds, we propose a new concept and definition at two different levels: the ecological threshold points, i.e. the turning points of quantitative changes to qualitative changes, which can be considered as ecological red lines; the ecological threshold zones, i.e. the regime shifts of the quantitative changes among different stable states, which can be considered as the yellow and/or orange warning boundaries of the gradual ecological changes. The yellow thresholds mean that an ecosystem can return to a stable state by its self-adjustment, the orange thresholds indicate that the ecosystem will stay in the equilibrium state after interference factors being removed, whereas the red thresholds, as the critical threshold points, indicate that the ecosystem will undergo irreversible degradation or even collapse beyond those points. We also summarizes two types of popular Methods in determining ecological thresholds: statistical analysis and modeling based on data of field observations. The applications of ecological thresholds in ecosystem service, biodiversity conservation and ecosystem management research are also reviewed. Future research on ecological thresholds should focus on the following aspects: (1) methodological development for measurement and quantification of ecological thresholds; (2) emphasizing the scaling effect of ecological thresholds and establishment of national-scale observation system and network; and (3) implementation of ecological thresholds as early warning tools in ecosystem management and delimiting ecological red lines.     

Retinal Vessel Width Measurement at Branchings Using an Improved Electric Field Theory-Based Graph Approach

The retinal vessel width relationship at vessel branch points in fundus images is an important biomarker of retinal and systemic disease. We propose a fully automatic method to measure the vessel widths at branch points in fundus images. The method is a graph-based method, in which a graph construction method based on electric field theory is applied which specifically deals with complex branching patterns. The vessel centerline image is used as the initial segmentation of the graph. Branching points are detected on the vessel centerline image using a set of detection kernels. Crossing points are distinguished from branch points and excluded. The electric field based graph method is applied to construct the graph. This method is inspired by the non-intersecting force lines in an electric field. At last, the method is further improved to give a consistent vessel width measurement for the whole vessel tree. The algorithm was validated on 100 artery branchings and 100 vein branchings selected from 50 fundus images by comparing with vessel width measurements from two human experts.     

Identification and molecular mapping of two QTLs with major effects for resistance to Fusarium head blight in wheat

Fusarium head blight (FHB) is a devastating disease of wheat worldwide. Novel sources of resistance are critical for improving FHB resistance levels in wheat. From a large-scale evaluation of germplasm for reactions to FHB, we identified one wheat accession (PI 277012) that consistently showed a high level of resistance in both greenhouse and field experiments. To characterize the FHB resistance in this accession, we developed a doubled haploid (DH) mapping population consisting of 130 lines from the cross between PI 277012 and the hard red spring wheat cultivar ‘Grandin’. The DH population was then evaluated for reactions to FHB in three greenhouse seasons and five field environments. Based on a linkage map that consisted of 340 SSR markers spanning 2,703 cM of genetic distance, two major quantitative trait loci (QTLs) for FHB resistance were identified on chromosome arms 5AS and 5AL, with each explaining up to 20 and 32% of the variation in FHB severity, respectively. The two QTLs also showed major effects on reducing the percentage of Fusarium damaged kernels (FDK) and deoxynivalenol (DON) accumulation in seeds. FHB resistance has not previously been reported to be associated with this particular genomic region of chromosome arm 5AL, thus indicating the novelty of FHB resistance in PI 277012. Plant maturity was not associated with FHB resistance and the effects of plant height on FHB resistance were minor. Therefore, these results suggest that PI 277012 is an excellent source for improving FHB resistance in wheat. The markers identified in this research are being used for marker-assisted introgression of the QTLs into adapted durum and hard red spring wheat cultivars.     

Whole genome mapping in a wheat doubled haploid population using SSRs and TRAPs and the identification of QTL for agronomic traits

Genetic maps are useful for detecting quantitative trait loci (QTL) associated with quantitative traits and for marker-assisted selection (MAS) in breeding. In this research, we used the wheat × maize method to develop a doubled haploid (DH) population derived from the synthetic hexaploid wheat (SHW) line TA4152-60 and the North Dakota hard red spring wheat line ND495. The population consisted of 213 lines, of which a subset of 120 lines was randomly selected and used to construct linkage maps of all 21 chromosomes and for QTL detection. The whole genome maps consisted of 632 markers including 410 SSRs, 218 TRAPs, 1 RFLP, and 3 phenotypic markers, and spanned 3,811.5 cM with an average density of one marker per 6.03 cM. Telomere sequence-based TRAPs allowed us to define the ends of seven linkage groups. Analysis revealed major QTLs associated with the traits of days to heading on chromosomes 5A and 5B, plant height on chromosomes 4D and 5A, and spike characteristics on chromosomes 3D, 4A, 4D, 5A and 5B. The DH population and genetic map will be a useful tool for the identification of disease resistance QTL and agronomically important loci, and will aid in the identification and development of markers for MAS. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Human visual system integrates color signals along a motion trajectory

Whether fundamental visual attributes, such as color, motion, and shape, are analyzed separately in specialized pathways has been one of the central questions of visual neuroscience. Although recent studies have revealed various forms of cross-attribute interactions, including significant contributions of color signals to motion processing, it is still widely believed that color perception is relatively independent of motion processing. Here, we report a new color illusion, motion-induced color mixing, in which moving bars, the color of each of which alternates between two colors (e.g., red and green), are perceived as the mixed color (e.g., yellow) even though the two colors are never superimposed on the retina. The magnitude of color mixture is significantly stronger than that expected from direction-insensitive spatial integration of color signals. This illusion cannot be ascribed to optical image blurs, including those induced by chromatic aberration, or to involuntary eye movements of the observer. Our findings indicate that color signals are integrated not only at the same retinal location, but also along a motion trajectory. It is possible that this neural mechanism helps us to see veridical colors for moving objects by reducing motion blur, as in the case of luminance-based pattern perception.     

不同性状的棉花及其杂交F1代对棉铃虫的抗性

通过连续两年的田间试验,系统、全面地研究了棉花对棉铃虫(Helicoverpa armigera)的形态抗虫作用。研究结果表明：在小区试验条件下,以百株累积卵量、百株平均幼虫量及百株平均蕾铃受害量为考察指标,红叶可使危害减轻28.1%、31.45%和36.O%;鸡脚叶可使其下降19.0%、25.4%和28.4%;窄卷苞叶使其降低25.8%、32.9%和34.0%;光叶使各指标分别降低32.7%、35.1%和37.3%。高棉酚(油腺)抗性主要表现为对幼虫的抗生作用,使幼虫量下降了45.1%,使蕾铃受害量下降了51.4%。此外,研究还表明,两种抗虫性状的抗性效果有累加作用,鸡脚叶与红叶联合作用使三项指标分别下降达48.3%、55.2%和57.9%;红叶与窄卷苞叶则使危害减轻了52.7%、58.3%和60.6%;具有光叶与较密油腺两个抗虫性状的品种受害可减轻29.9%、54.9%和58.3%。将一些具有相对性状的品种进行杂交,其F₁有不同的抗虫表现。红叶、鸡脚叶和光叶品种与其对照杂交后的F1代因在不同程度上保持了抗虫性状故能表现出抗性,而窄卷苞叶品种与其对照杂交后F1代苞叶正常,则未能表现出抗性。因小区条件限制了无蜜腺抗性的表达,无蜜腺小区未表现出明显差异。     

Overexpression of homologous phytochrome genes in tomato: exploring the limits in photoperception

Transgenic tomato [Lycopersicon esculentum (=Solanum lycopersicum)] lines overexpressing tomato PHYA, PHYB1, or PHYB2, under control of the constitutive double-35S promoter from cauliflower mosaic virus (CaMV) have been generated to test the level of saturation in individual phytochrome-signalling pathways in tomato. Western blot analysis confirmed the elevated phytochrome protein levels in dark-grown seedlings of the respective PHY overexpressing (PHYOE) lines. Exposure to 4 h of red light resulted in a decrease in phytochrome A protein level in the PHYAOE lines, indicating that the chromophore availability is not limiting for assembly into holoprotein and that the excess of phytochrome A protein is also targeted for light-regulated destruction. The elongation and anthocyanin accumulation responses of plants grown under white light, red light, far-red light, and end-of-day far-red light were used for characterization of selected PHYOE lines. In addition, the anthocyanin accumulation response to different fluence rates of red light of 4-d-old dark-grown seedlings was studied. The elevated levels of phyA in the PHYAOE lines had little effect on seedling and adult plant phenotype. Both PHYAOE in the phyA mutant background and PHYB2OE in the double-mutant background rescued the mutant phenotype, proving that expression of the transgene results in biologically active phytochrome. The PHYB1OE lines showed mild effects on the inhibition of stem elongation and anthocyanin accumulation and little or no effect on the red light high irradiance response. By contrast, the PHYB2OE lines showed a strong inhibition of elongation, enhancement of anthocyanin accumulation, and a strong amplification of the red light high irradiance response.     

Estrogen mitogenic action. III. Is phenol red a “red herring”?

The reported estrogenic action of phenol red and/or its lipophilic contaminants has led to the widespread use of indicator-free culture medium to conduct endocrine studies in vitro. Because we have recently developed methods to measure large-magnitude estrogen effects in the tissue culture medium containing phenol red, we concluded that the indicator issue required further evaluation. To do this, we selected nine estrogen receptor positive (ER+) cell lines representing four target tissues and three species. We investigated phenol red using five different experimental protocols. First, 17beta-estradiol (E2) responsive growth of all nine ER+ cells lines was compared in the medium with and without the indicator. Second, using representative lines we asked if phenol red was mitogenic in the indicator-free medium. The dose-response effects of phenol red were compared directly to those of E2. Third, we asked if tamoxifen-inhibited growth equally in phenol red-containing and indicator-free medium. This study was based on a report indicating that antiestrogen effects should be seen only in phenol red-containing medium. Fourth, we asked if phenol red displaced the binding of 3H-E2 using ERK intact human breast cancer cells. Fifth, we compared E2 and phenol red as inducers of the progesterone receptor using a human breast cancer cell line. All the experiments presented in this report support the conclusion that the concentration of phenol red contaminants in a standard culture medium available today is not sufficient to cause estrogenic effects. In brief, our studies indicate that the real issue of how to demonstrate estrogenic effects in culture resides elsewhere than phenol red. We have found that the demonstration of sex steroid hormone-mitogenic effects in culture depends upon conditions that maximize the effects of a serum-borne inhibitor(s). When the effects of the inhibitor are optimized, the presence or absence of phenol red makes no everyday difference to the demonstration of estrogen mitogenic effects with several target cell types from diverse species.     

Immunologic characterization of hairy cell leukemias in continuous culture.

The immunobiologic characteristics of three continuous cell lines established from hairy cell leukemia cells were investigated. All three cell lines continued to produce tartrate-resistant acid phosphatase, the enzymatic marker of hairy cells. Two of these cell lines were B lymphoid in nature. They carried Fc and C receptors, had surface and internal immunoglobulin, and did not form spontaneous sheep red blood cell rosettes. Experiments employing biosynthetic radiolabeling of immunoglobulin demonstrated distinctive immunoglobulin kinetics for each of these two hairy cell lines. One cell line remained quite similar to the original hairy cells from which it was derived whereas the other B lymphoid hairy cell line had undergone a switch in the immunoglobulin isotype produced. The third hairy cell leukemia line was shown to be of thymic derivation. These cells formed spontaneous sheep red blood cell rosettes and did not carry Fc or C receptors. The spontaneous sheep red blood cell rosette-forming cells contained tartrate-resistant acid phosphatase. They did not possess surface on internal immunoglobulin and did not synthesize immunoglobulin in vitro. Hairy cell leukemia cells maintained in permanent cell culture retain their immunobiologic properties and offer the opportunity for indepth study of these unusual cells.     

Efficacy of bifenthrin treatment zones against red imported fire ant

Exclusion of ants, particularly red imported fire ant, Solenopsis invicta (Buren), from homes, nursing facilities, hospitals, and electrical housings is an important strategy in urban and rural pest control. We conducted a laboratory bioassay to determine the repellency of granular bifenthrin (Talstar: rate 2.087 kg of formulated product/92.88 m2 or 4.6 lb formulated product/1000 feet2 or 4.2 g active ingredient/92.88 m2) to S. invicta foragers. In the field, we compared the efficacy of three widths (0.3, 2.0, and 3.0 m) of granular bifenthrin-treated zones at the rate 2.087 kg of formulated product/92.88 m2 and investigated the survival of individual ants successfully crossing the respective zones. Granular bifenthrin was nonrepellent to fire ant foragers in the laboratory. The 2.0- and 3.0-m treatment zones provided 100% protection for 7 wk after treatment and provided a reduction in the number of ants breaching the treated zone compared with the control for the remaining 9 wk of the study. This level of control may be tolerable for homeowners and is, therefore, considered an effective treatment for 15 wk after treatment. Hospitals, nursing homes, and electrical boxes would have to be treated on a monthly or bimonthly to remain ant free.     

A test of the visual acuity of the locust eye

Targets consisting of solid rectangles (bright on a dark ground), of a range of widths, or pairs of thin lines of separation equal to the width of each rectangle, were used to evoke on, or movement responses in, the DCMD and other visual interneurones in the locust (Schistocerca gregaria). It was found that, judged from the discharges in these interneurones, both types could distinguish solid from paired-line figures of identical subtense, down to an angle of 0.4 degrees. Such an angle is well within the values of the eye parameters DeltaP and Deltaphi. Similar results were obtained with figures of the reversed contrast, showing that acuity was maintained even in the presence of a bright surrounding.     

Triplet state of tryptophan in proteins: the nature of the optically detected magnetic resonance lines

Optical detection of magnetic resonance (ODMR) has been employed to examine the homogeneity of the tryptophan environment, both of the isolated residue in solvent, and of tryptophan in glucagon and lysozyme and azurin B (Pseudomonas aeruginosa). From the shifts in the zero-field splittings, we can safely conclude that tryptophan in lysozyme, azurin B, or glucagon does not have the same type of solvent interaction as the free residue. However, by "burning holes" in the OSMR lines, it is evident that the lines in these cases are inhomogeneously broadened. From the relative line widths and hole widths, it appears that ODMR can be used to examine the relative diversity of interactions for a luminescent amino acid in a protein. We have followed the ODMR line characteristics in a progression from free N-acetyl-L-tryptophanamide, to tryptophan in lysozyme, to "denatured" lysozyme, and present evidence that the line widths narrow as the tryptophan residues become less solvent accessible.     

Far-Red Light Reflection from Green Leaves and Effects on Phytochrome-Mediated Assimilate Partitioning under Field Conditions

The influence of plant spacing and row orientation on spectral distribution of light received by growing soybean (Gylcine max [L.] Merr.) plants was measured under field conditions. Light absorption, reflection and transmission of individual leaves showed that most of the blue and red was absorbed while most of the far-red was either reflected or transmitted. Plants growing in the field received different ratios of far-red relative to red, depending on nearness and/or orientation of other vegetation. Plants grown in close-spaced rows, or high population densities, received higher far-red/red ratios than did those grown in wide rows, or sparse populations. Heliotropic movements of the leaves also contributed to the far-red reflection patterns associated with row orientation. Under field conditions, differences in far-red/red ratios associated with nearness of competing vegetation became more pronounced with low solar angle near the end of the day. Plants exposed to far-red for 5 minutes at the end of each day in controlled environments, and those grown in close-spaced rows in the field, developed longer internodes and fewer branches. Red, far-red photoreversibility in the controlled environment study indicated involvement of phytochrome. Dry matter partitioning among plant components in the field was related to far-red/red light ratio received during growth and development.     

Laboratory Performance Predicts the Success of Field Releases in Inbred Lines of the Egg Parasitoid Trichogramma pretiosum (Hymenoptera: Trichogrammatidae)

In this study we assessed the relationship between the laboratory and field performance of different isofemale lines of Trichogramma pretiosum Riley. In comparative assays, we used three rare mitochondrial haplotypes as genetic markers of the isofemale lines, and by introgressing these mitochondrial haplotypes into each of 15 genetically different nuclear lines, also tested the assumption that mitochondria are neutral markers. In a laboratory trial, 45 isofemale lines (15 nuclear genotypes x three mitochondrial haplotypes) were ranked in three categories (best, intermediate and worst) according to the mean offspring production and the proportion of female offspring. Subsequently, lines from each of the three categories were selected for field releases to quantify field parasitism on Ephestia kuehniella. Temporally separate releases were done in a transgenic Bt cornfield, with four plots, each with 50 points of recapture. The points of recapture consisted of trap cards with eggs of E. kuehniella collected daily. The trap cards were maintained in the laboratory at 25°C until the adult wasps emerged, and the maternal identity of the wasps was determined using qPCR and high-resolution melt curve analysis to determine the mitochondrial haplotype. The results showed that these measures of laboratory performance (fecundity and offspring sex ratio) were good predictors of field success in T. pretiosum. We also report strong evidence discrediting the assumption that mitochondria are neutral, in view of the correlation between performance and mitochondrial haplotype.