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Abstact: —The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor and its target genes play a fundamental role in detoxification, regulation of developmental processes, maintenance of homeostasis, and in the occurrence of oncological and autoimmune diseases and drug metabolism. The high conservatism of vertebrate AHR allowed us to study its functions in vivo using transformed Drosophilamelanogaster fruit flies with human or mouse AHR gene and compare the ectopic effect of their expression with the expression of spineless gene, Drosophila AHR homologue. This work demonstrates for the first time that vertebrate AHR exhibits its functional activity in Drosophila embryogenesis, in leg imaginal discs, and in somatic cells of the female reproductive system in the absence of exogenous ligands. [ABSTRACT FROM AUTHOR]

Cacti are economic ornamental plants whose value varies with market trends. Recently, cacti with new morphologies compared to the original plant have decreased in popularity. Colchicine is a tricyelic alkaloid substance, It is an inhibitor of mitosis thus preventing the formation of microtubuli and the mitotic spindle. This research investigated the effect of colchicine on inducing morphological and anatomical traits in Gymnocalycium mihanovichii using a 2-factor factorial completely randomized design (CRD) The first factor was the duration of the dipped stem at 24 and 48 h, while the second factor was the colchicine concentration at 0.25 and 0.5 %. Results indicated that G. mihanovichii treated with colchicine at different concentrations and dipping durations showed statistically significant differences in plant height, stem diameter, number of spines and root length. G. mihanovichii treated with 0.50 % colchicine for 48 h developed a new morphological trait called spineless cactus. Occurrences of larger sized stomata with lower frequency per unit area were statistically significantly different after treatment with 0.25 % colchicine for 24 h. Maximum length of stomatal guard cells was 50.33 µm. [ABSTRACT FROM AUTHOR]

To assess the response of two safflower genotypes to auxin foliar application under late-season drought stress using a factorial split-plot experiment with the randomised complete block design, a two-year experiment (2016-2017 and 2017-2018) was conducted in Iran. The watering regime as specified in two levels including, regular irrigation and drought stress in main plots and two safflower genotypes and auxin foliar application in two levels including non-foliar application (control) and auxin foliar application at a concentration of 30 ppm were categorised in subplots. Drought stress at the seed filling stage reduced the safflower seed and oil yield. Moreover, a significant drought-induced decrease in linoleic acid, palmitic acid and behenic acid content, as well as an increase in oleic acids, was observed in two safflower genotypes. Among two safflower genotypes, the early maturing genotype less affected by drought and Goldasht had higher seed yield than the Padideh by 814 kg/ha, respectively. Auxin foliar application alleviates the adverse effects of drought, which led to an 18% increase in seed yield and components. However, the auxin application had no effect on the safflower seed oil content but palmitic acid content was affected by auxin foliar application. Generally, safflower along with auxin application can be recommended to develop safflower cultivation in semi-arid areas.

A new eggplant cultivar ‘Shiko 17-22’ was developed with the characteristics of high yield, pickling ability, parthenocarpy and spine absence. The fruit shape of ‘Shiko 17-22’ is long obovate. The fruit of this cultivar has an excellent character with high quality and glossy skin. This cultivar, which is characterized by stable parthenocarpy, requires fewer working hours to force culturing, and is spineless. The marketable yield of ‘Shiko 17-22’ is greater than those of ‘Senryo’ and ‘Togenashikiraku,’ and its breaking strength of the fruit skin is between those of the two cultivars. The taste evaluation after pickle processing of this cultivar is equivalent to ‘Senryo’, and superior to ‘Togenashikiraku’. Application for cultivar registration was made in November 2021, and the application was made public in March 2022. [ABSTRACT FROM AUTHOR]

To assess the response of two safflower genotypes to auxin foliar application under late-season drought stress using a factorial split-plot experiment with the randomised complete block design, a two-year experiment (2016-2017 and 2017-2018) was conducted in Iran. The watering regime as specified in two levels including, regular irrigation and drought stress in main plots and two safflower genotypes and auxin foliar application in two levels including non-foliar application (control) and auxin foliar application at a concentration of 30 ppm were categorised in subplots. Drought stress at the seed filling stage reduced the safflower seed and oil yield. Moreover, a significant drought-induced decrease in linoleic acid, palmitic acid and behenic acid content, as well as an increase in oleic acids, was observed in two safflower genotypes. Among two safflower genotypes, the early maturing genotype less affected by drought and Goldasht had higher seed yield than the Padideh by 814 kg/ha, respectively. Auxin foliar application alleviates the adverse effects of drought, which led to an 18% increase in seed yield and components. However, the auxin application had no effect on the safflower seed oil content but palmitic acid content was affected by auxin foliar application. Generally, safflower along with auxin application can be recommended to develop safflower cultivation in semi-arid areas. [ABSTRACT FROM AUTHOR]

Development is often driven by signaling and lineage-specific cues, yielding highly uniform and reproducible outcomes. Development also involves mechanisms that generate noise in gene expression and random patterns across tissues. Cells sometimes randomly choose between two or more cell fates in a mechanism called stochastic cell fate specification. This process diversifies cell types in otherwise homogenous tissues. Stochastic mechanisms have been extensively studied in prokaryotes where noisy gene activation plays a pivotal role in controlling cell fates. In eukaryotes, transcriptional repression stochastically limits gene expression to generate random patterns and specify cell fates. Here, we review our current understanding of repressive mechanisms that produce random patterns of gene expression and cell fates in flies, plants, mice, and humans. • Development involves mechanisms that generate noise in gene expression and random patterns across tissues. • Cells sometimes randomly choose between two or more cell fates to diversify cell types in otherwise homogenous tissues. • Repression stochastically limits expression to generate random patterns and specify cell fates in flies, mice, and humans. [ABSTRACT FROM AUTHOR]

Diversification of neuronal subtypes often requires stochastic gene regulatory mechanisms. How stochastically expressed transcription factors interact with other regulators in gene networks to specify cell fates is poorly understood. The random mosaic of color-detecting R7 photoreceptor subtypes in Drosophila is controlled by the stochastic on/off expression of the transcription factor Spineless (Ss). In SsON R7s, Ss induces expression of Rhodopsin 4 (Rh4), whereas in SsOFF R7s, the absence of Ss allows expression of Rhodopsin 3 (Rh3). Here, we find that the transcription factor Runt, which is initially expressed in all R7s, is sufficient to promote stochastic Ss expression. Later, as R7s develop, Ss negatively feeds back onto Runt to prevent repression of Rh4 and ensure proper fate specification. Together, stereotyped and stochastic regulatory inputs are integrated into feedforward and feedback mechanisms to control cell fate. • Stochastic Ss expression determines the random mosaic of R7 subtypes in the fly eye. • The transcription factor Run is sufficient to promote stochastic Ss expression. • Ss negatively feeds back onto Run to prevent repression of Rh4. • Stereotyped and stochastic regulatory inputs are integrated to control cell fate. [ABSTRACT FROM AUTHOR]

The Sp family of transcription factors plays important functions during development and disease. An evolutionary conserved role for some Sp family members is the control of limb development. The family is characterized by the presence of three C2H2-type zinc fingers and an adjacent 10 aa region with an unknown function called the Buttonhead (BTD) box. The presence of this BTD-box in all Sp family members identified from arthropods to vertebrates, suggests that it plays an essential role during development. However, despite its conservation, the in vivo function of the BTD-box has never been studied. In this work, we have generated specific BTD-box deletion alleles for the Drosophila Sp family members Sp1 and buttonhead (btd) using gene editing tools and analyzed its role during development. Unexpectedly, btd and Sp1 mutant alleles that lack the BTD-box are viable and have almost normal appendages. However, in a sensitized background the requirement of this domain to fully regulate some of Sp1 and Btd target genes is revealed. Furthermore, we have also identified a novel Sp1 role promoting leg vs antenna identity through the repression of spineless (ss) expression in the leg, a function that also depends on the Sp1 BTD-box. • The BTD-box is a conserved domain of the Sp family of transcription factors. • We investigated its in vivo role using BTD-box deletion alleles of Sp1 and btd. • We highlight a role for the BTD-box in the regulation of several Sp1 and Btd target genes. • Sp1 promotes leg vs antenna identity through ss regulation in the leg. [ABSTRACT FROM AUTHOR]

This investigation was carried out at experimental and research Farm, Faculty of Agriculture, Zagazig University, Egypt during six winter seasons 2012/2013, 2013/2014, 2014/2015, 2015/2016, 2016/2017 and 2017/2018. The aim of this study is to evaluate earliness and spineless mutant lines of safflower. The morphological traits (earliness, number of days to maturity) were recorded for two lines of safflower, line III and line VI and their promising mutant lines. The results confirmed the stability of 8 promising mutant lines for line III, (4, 7, 9, 10, 12, 14, 17, 18) and 6 promising mutant lines for line VI, (1, 2, 5, 6, 9, 7). In the M10 generation, 9 criteria were recorded, 1- plant height (cm), 2-number of branches per plant, 3-number of capitula per plant, 4-number of seeds per capitulam,5-number of seeds per plant, 6-100 seed weight (g), 7-seed weight/plant (g), 8-days to maturity, 9- oil (%). High broad sense heritability (h²) of No. of capitula per plant, 100-seed weight, seed weight per plant, days to maturity and oil content were 79.16%, 77.95%, 94.91%, 79.23% and 69.41%, respectively among line III and their mutant lines. The present study confirmed that the relationship between characters under study varied between genotypes for example, oil content slightly negative correlated with seed weight per plant and was different among genotypes (-0.2495, - 0.0678 and - 0.2358) for line III and line VI and for over all genotypes, respectively. These results confirmed that selection of oil content and seed weight per plant could be achieved in line VI and their mutants (- 0.0678). In addition, highly positive correlation between seed weight per plant and each of No. of capitula per plant and No. of seeds per plant at line VI, was observed. These results showed the simple heritable system of days to maturity, than the spineless criteria. These promising mutant lines had 168 and 170 days to maturity of line 4 and 7 from line III and 177 and 182 days of line 2 and 5 from line VI by comparison to 180 and 188 days for control of line III and line VI, respectively. These results suggest the improvement possibility of new Egyptian varieties for cultivation of harsh and poor land desert. [ABSTRACT FROM AUTHOR]

A wide array of sensilla are distributed on insect antennae, and they play a variety of important roles. Rice planthoppers, destructive pests on rice, have a unique antenna sensilla structure called the 'sensory plaque organ'. The spineless (ss) gene encodes a bHLH‐PAS transcription factor and plays a key role in antenna development. In the current study, a 3029 bp full‐length cDNA of the Nilaparvata lugensss gene (Nlss) was cloned, and it encodes 654 amino acid residues. The highest level of Nlss expression was detected in the thorax of fourth‐instar nymphs. Knockdown of Nlss in nymphs led to a decrease in the number and size of plaque organs. Moreover, the flagella of the treated insects were poorly developed, wilted, and even dropped off from the pedicel. Nlss‐knockdown also resulted in twisted wings in both long‐winged and short‐winged brown planthoppers. Y‐type olfactometer analyses indicated that antenna defects originating from Nlss depletion resulted in less sensitivity to host volatiles. This study represents the first report of the characteristics and functions of Nlss in N. lugens antenna and wing development and illuminates the function of the plaque organ of N. lugens in host volatile perception. [ABSTRACT FROM AUTHOR]

Each individual perceives the world in a unique way, but little is known about the genetic basis of variation in sensory perception. In the fly eye, the random mosaic of color-detecting R7 photoreceptor subtypes is determined by stochastic on/off expression of the transcription factor Spineless (Ss). In a genome-wide association study, we identified a naturally occurring insertion in a regulatory DNA element in ss that lowers the ratio of SsON to SsOFF cells. This change in photoreceptor fates shifts the innate color preference of flies from green to blue. The genetic variant increases the binding affinity for Klumpfuss (Klu), a zinc finger transcriptional repressor that regulates ss expression. Klu is expressed at intermediate levels to determine the normal ratio of SsON to SsOFF cells. Thus, binding site affinity and transcription factor levels are finely tuned to regulate stochastic expression, setting the ratio of alternative fates and ultimately determining color preference.

How differential levels of gene expression are controlled in postmitotic neurons is poorly understood. In the Drosophila retina, expression of the transcription factor Defective Proventriculus (Dve) at distinct cell type-specific levels is required for terminal differentiation of color- and motion-detecting photoreceptors. Here, we find that the activities of two cis-regulatory enhancers are coordinated to drive dve expression in the fly eye. Three transcription factors act on these enhancers to determine cell-type specificity. Negative autoregulation by Dve maintains expression from each enhancer at distinct homeostatic levels. One enhancer acts as an inducible backup ('dark' shadow enhancer) that is normally repressed but becomes active in the absence of the other enhancer. Thus, two enhancers integrate combinatorial transcription factor input, feedback and redundancy to generate cell type-specific levels of dve expression and stable photoreceptor fate. This regulatory logic may represent a general paradigm for how precise levels of gene expression are established and maintained in post-mitotic neurons. [ABSTRACT FROM AUTHOR]

DNA elements act across long genomic distances to regulate gene expression. During transvection in Drosophila , DNA elements on one allele of a gene act between chromosomes to regulate expression of the other allele. Little is known about the biological roles and developmental regulation of transvection. Here, we study the stochastic expression of spineless (ss) in photoreceptors in the fly eye to understand transvection. We determine a biological role for transvection in regulating expression of naturally occurring ss alleles. We identify DNA elements required for activating and repressing transvection. Different enhancers participate in transvection at different times during development to promote gene expression and specify cell fates. Bringing a silencer element on a heterologous chromosome into proximity with the ss locus "reconstitutes" the gene, leading to repression. Our studies show that transvection regulates gene expression via distinct DNA elements at specific timepoints in development, with implications for genome organization and architecture. [Display omitted] • Transvection averages expression from wild-derived alleles of spineless • Enhancers activate expression between chromosomes at distinct developmental times • An insulator and Polycomb Response Elements facilitate repressive transvection • spineless transvection occurs in the presence of large chromosomal rearrangements R7 photoreceptor subtypes are randomly patterned in the fly eye in a 2:1 ratio. Transvection mediates expression of the fate determinant spineless. Urban et al. find that transvection occurs between wild-derived alleles of spineless. They dissect the activating and repressive DNA elements required for this process. [ABSTRACT FROM AUTHOR]

Stochastic mechanisms diversify cell fates during development. How cells randomly choose between two or more fates remains poorly understood. In the Drosophila eye, the random mosaic of two R7 photoreceptor subtypes is determined by expression of the transcription factor Spineless (Ss). We investigated how cis -regulatory elements and trans factors regulate nascent transcriptional activity and chromatin compaction at the ss gene locus during R7 development. The ss locus is in a compact state in undifferentiated cells. An early enhancer drives transcription in all R7 precursors, and the locus opens. In differentiating cells, transcription ceases and the ss locus stochastically remains open or compacts. In SsON R7s, ss is open and competent for activation by a late enhancer , whereas in SsOFF R7s, ss is compact, and repression prevents expression. Our results suggest that a temporally dynamic antagonism, in which transcription drives large-scale decompaction and then compaction represses transcription, controls stochastic fate specification. [Display omitted] • spineless is off, and the locus is in a compact state in undifferentiated cells • The early enhancer drives expression, and the locus opens • Expression ceases, and the locus recompacts or remains open • Repression in a subset of R7s limits expression driven by the late enhancer Cells sometimes randomly choose between fates during development. In Drosophila , a random mosaic of photoreceptor subtypes is determined by the spineless gene. Voortman et al. find that spineless is regulated by a dynamic interplay between transcription and chromatin compaction during fly eye development. [ABSTRACT FROM AUTHOR]

Background: A complex life cycle, such as complete metamorphosis, is a key innovation that can promote diversification of species. The evolution of a morphologically distinct larval stage is thought to have enabled insects to occupy broader ecological niches and become the most diverse metazoan taxon, yet the extent to which larval and adult morphologies can evolve independently remains unknown. Perturbation of larval limb regeneration allows us to generate larval legs and antennae with altered limb morphologies, which may be used to explore the developmental continuity that might exist between larval and adult appendages. In this study, we determined the roles of several appendage patterning transcription factors, abrupt (ab), dachshund (dac), Distal-less (Dll), and spineless (ss), in the red flour beetle, Tribolium castaneum, during larval appendage regeneration. The functions of these genes in regenerating and non-regenerating limbs were compared using RNA interference. Results: During limb regeneration, dac and ss were necessary to re-pattern the same larval structures as those patterned during embryogenesis. Removal of these two genes led to larval appendage patterning defects that were carried over to the adult legs. Surprisingly, even though maternal knockdown of ab had minimal effects on limb allocation and patterning in the embryo, it was necessary for blastema growth, an earlier phase of regeneration. Finally, knockdown of Dll prevented the blastema-like bumps from re-differentiating into appendages. Conclusions: Our results suggest that, similar to vertebrates, the re-patterning phase of Tribolium larval limb regeneration relies on the same genes that are used during embryonic limb patterning. Thus, the re-patterning phase of regeneration is likely to be regulated by taxon-specific patterning mechanisms. Furthermore, Ab and Dll appear to play important roles during blastema proliferation and re-differentiation, respectively. Finally, our results show that continuity exists between larval and adult limb patterning, and that larval and adult leg morphologies may be developmentally coupled. Thus, the evolution of imaginal discs may have been a key step towards completely removing any developmental constraints that existed between larval and adult phenotypes. [ABSTRACT FROM AUTHOR]

Abstract: The morphology of insect appendages, such as the number and proportion of leg tarsal segments, is immensely diverse. In Drosophila melanogaster, adult legs have five tarsal segments. Accumulating evidence indicates that tarsal segments are formed progressively through dynamic changes in the expression of transcription factor genes, such as Bar genes, during development. In this study, to examine further the basis of progressive tarsal patterning, the precise expression pattern and function of several transcription factor genes were investigated in relation to the temporal regulation of Bar expression. The results indicate that nubbin is expressed over a broad region at early stages but gradually disappears from the middle of the tarsal region. This causes the progressive expansion of rotund expression, which in turn progressively represses Bar expression, leading to the formation of the tarsal segment 3. The region corresponding to the tarsal segment 4 is formed when apterous expression is initiated, which renders Bar expression refractory to rotund. In addition, the tarsal segment 2 appears to be derived from the region that expresses Bar at a very early stage. Cessation of Bar expression in this region requires the function of spineless, which also regulates rotund expression. These findings indicate that the temporally dynamic regulatory interaction of these transcription factor genes is the fundamental basis of the progressive patterning of the tarsal region. [Copyright &y& Elsevier]

Abstract: It is currently thought that antennal target genes are activated in Drosophila by the combined action of Distal-less, homothorax, and extradenticle, and that the Hox gene Antennapedia prevents activation of antennal genes in the leg by repressing homothorax. To test these ideas, we analyze a 62bp enhancer from the antennal gene spineless that is specific for the third antennal segment. This enhancer is activated by a tripartite complex of Distal-less, Homothorax, and Extradenticle. Surprisingly, Antennapedia represses the enhancer directly, at least in part by competing with Distal-less for binding. We show that Antennapedia is required in the leg only within a proximal ring that coexpresses Distal-less, Homothorax and Extradenticle. We conclude that the function of Antennapedia in the leg is not to repress homothorax, as has been suggested, but to directly repress spineless and other antennal genes that would otherwise be activated within this ring. [ABSTRACT FROM AUTHOR]

The morphology of insect antennae varies widely among species, but our understanding of antennal development comes almost solely from studies of one species—the fruit fly, Drosophila melanogaster. Moreover, this knowledge applies mostly to adult structures, since Drosophila lacks external larval appendages. In contrast to Drosophila, the red flour beetle, Tribolium castaneum, has both larval and adult antennae, which are very different from one another in morphology. Thus, Tribolium provides an ideal system to compare modes of antennal development both within and between species. Here, we report that the Tribolium ortholog of spineless ( Tc-ss) is required in both the larval and adult antennae. Knockdown of Tc-ss by RNAi during either larval or imaginal development causes transformation of the distal portion of the antennae to legs. Thus, the function of ss is conserved between Drosophila and Tribolium with respect to adult antennal specification and also between Tribolium larval and adult antennal development. The similarity of the Tc-ss RNAi phenotype to that of a classically described Tribolium mutation, antennapedia ( ap) (of no relationship to the Drosophila Hox gene of the same name), led us to characterize the original ap mutation and two newly identified ap alleles. Our mapping and phenotypic data suggest that Tc-ss is the best candidate for the ap locus. These results represent a first step in characterizing larval and adult antennal patterning in Tribolium, which should provide important insights into the evolution of insect antennal development. [ABSTRACT FROM AUTHOR]

Abstract: Hox genes control regional identity along the anterior–posterior axis in various animals. Each region contains morphological characteristics specific to that region as well as some that are shared by several different regions. The mechanism by which one Hox gene regulates region-specific characteristics has been extensively analyzed. However, little attention has been paid to the mechanism by which different Hox genes regulate the same characteristics in different regions. Here, we show that two Hox genes in Drosophila, Sex combs reduced and Ultrabithorax, employ different mechanisms to achieve the same out-put, the absence of sternopleural bristles, in the prothorax and metathorax, respectively. Sternopleural bristles are characteristics of the mesothorax and we found that spineless is involved in their development. Analysis of the regulatory relationship between Hox genes and spineless indicated that ss expression is repressed by Sex combs reduced in the prothorax. Since sole misexpression of ss could induce ectopic sternopleural bristle formation in the prothorax irrespective of the expression of Sex combs reduced, spineless repression appears to be critical for inhibition of sternopleural bristles by Sex combs reduced. In contrast, spineless was expressed in the metathorax independently of Ultrabithorax activity, indicating that Ultrabithorax blocks sternopleural bristle formation through mechanisms other than spineless repression. Our finding indicates that the same characteristics can be achieved in different segments by different Hox genes acting in different ways. [Copyright &y& Elsevier]

Abstract: The basic helix-loop-helix/Per-Arnt-Sim (bHLH-PAS) homology protein family is an important class of transcriptional regulators that are involved in a wide variety of biological processes. In a previous study, we characterized a novel bHLH-PAS factor ‘NXF’ as a new member of the mammalian bHLH-PAS family. If model animals have ortholog genes for NXF, they might have advantages for characterization of its function and regulation in vivo. Here we document cDNA cloning and characterization of putative NXF homolog genes (for NXF-like-factors) in Drosophila and C. elegans. Some conservation of the exon–intron gene architecture was noted in the bHLH-PAS domains among NXF-like-factors and human NXF. The NXF-like-factors selectively interacted with an Arnt ortholog in vitro assay. Moreover, they selectively associated with the mammalian NXF:Arnt2 binding element in the presence of the Arnt ortholog, and synergistically activated a mammalian NXF:Arnt-responsive promoter. These data strongly suggest that the Drosophila and C. elegans NXF-like-factors reported here are homologs of mammalian NXF. Further elucidation of whether they are true orthologs with the same function in vivo is now necessary. [Copyright &y& Elsevier]

Abstract: The transformation of antenna to leg is a classical model for understanding segmental fate decisions in Drosophila. The spineless (ss) gene encodes a bHLH-PAS transcription factor that plays a key role in specifying the identity of distal antennal segments. In this report, we identify the antennal disc enhancer of ss and then use enhancer-lacZ reporters to work out how ss antennal expression is regulated. The antennal determinants Distal-less (Dll) and homothorax (hth) are key activators of the antennal enhancer. Dll is required continuously and, when present at elevated levels, can activate the enhancer in regions devoid of hth expression. In contrast, homothorax (hth) is required only transiently both for activation of the enhancer and for specification of the aristal portion of the antenna. The antennal enhancer is repressed by cut, which determines its proximal limit of expression, and by ectopic Antennapedia (Antp). Repression by Antp is not mediated by hth, suggesting that ss may be a direct target of Antp. Finally, we show that ss + is not a purely passive target of its regulators: ss + partially represses hth in the third antennal segment and lies upstream of Dll in the development of the maxillary palp primordia. [Copyright &y& Elsevier]

The remarkable diversity of form in arthropods reflects flexible genetic programs deploying many conserved genes. In the insect model Drosophila melanogaster, diversity of form can be observed between serially homologous appendages or when a single appendage is transformed by homeotic mutations, such as the adult labial mouthparts that can present alternative antennal, prothoracic, or maxillary identities. We have examined the roles of the Hox selector genes proboscipedia ( pb) and Sex combs reduced ( Scr), and the antennal selectors homothorax ( hth) and spineless ( ss) in labial specification, by tissue-directed mitotic recombination. Whereas loss of pb function transforms labium to prothoracic leg, loss of Scr, hth, or ss functions results in little or no change in labial specification. Results of analysis of single and multiple mutant combinations support a genetic hierarchy in which the homeotic pb gene possesses a primary role. It is surprising to note that while loss of ss activity alone had no detected effect, all mutant combinations lacking both pb and ss yielded the most severe phenotype observed: stunted, apparently tripartite legs that may correspond to a default state. The roles of the four selector genes are functionally linked to a cell nonautonomous mechanism involving the coupled activities of the decapentaplegic ( dpp)/TGF-β and wingless ( wg)/Wnt signaling pathways. Accordingly, several mutant combinations impaired in dpp signaling were seen to reorient labial-to-leg transformations toward antennal aristae. A crucial aspect of selector function in development and evolution may be in regulating diffusible signals, including those emitted by dpp and wg. [ABSTRACT FROM AUTHOR]

Abstract: The spatial and temporal regulation of genes encoding transcription factors is essential for the proper development of multicellular organisms. In Drosophila leg development, the distal-most tarsus (ta5) is specified by the strong expression of a pair of Bar homeobox genes in late third instar. This expression is regulated under the control of the ta5 enhancer activated by Bar. No activation of the ta5 enhancer, however, occurs in early third instar when considerable Bar is produced. The ta5 enhancer was comprised of a basal enhancer required for driving Bar expression and a negative regulatory motif serving as a binding site for the heterodimer of Spineless and Tango, homologs of the mammalian dioxin receptor and aryl hydrocarbon nuclear translocator, respectively. The spineless and tango were essential for suppressing the basal enhancer activation in early third instar. The spineless was transiently expressed in early third instar in the Bar expression domain. ta5 Bar expression may thus be temporally regulated through transient inhibition of premature activation of the basal enhancer via specific binding of the Spineless/Tango heterodimer to the negative regulatory motif in early third instar and subsequent release from the inhibition due to the disappearance of spineless expression at later stages. [Copyright &y& Elsevier]

Carrot seeds normally have surface spines. The availability of a spineless mutant would be agronomically beneficial, eliminating the current efforts to remove those spines pre-sowing. Furthermore, the identification of spine-specific genes would provide insights into spine development in wild-type carrot seed. This effort could be facilitated through the use of an annealing control primer (ACP) system. Here, we employed a new and accurate reverse transcriptionpolymerase chain reaction (RT-PCR) that involves ACPs for identifying genes of interest. With these techniques, 11 expressed sequence tags (ESTs) were obtained for cloning and sequencing the genes that are differentially expressed in wild-type spiny seeds, but not in the spineless mutant. In all, 7 cDNAs exhibited significant sequence similarity with known genes from other species. These included cell wall-associated hydrolase, tail fiber assembly protein, transcriptional regulatory protein, berberine bridge enzyme, S-adenosyl methionine synthase, transketolase, and phenylalanyl t-RNA synthetase beta chain. Four other cDNA sequences had no significant identities with known genes. As revealed by RT-PCR, these genes regulate spine formation during the developmental stage. Our results suggest that PCR-based differential display RT-PCR techniques are a very useful tool for identifying spine-specific genes from carrot seeds. [ABSTRACT FROM AUTHOR]

The article focuses on the Black Diamond thornless trailing blackberry variety from the U.S. Department of Agriculture-Agricultural Research Service breeding program in Corville, Oregon. The variety is high-yielding, vigorous, adapted to machine harvesting and produces a very good processed product. Its fruit are firm and its drupelet epidermis is tough enough to be suited to some fresh market applications.

Abstract: Many organisms respond to toxic compounds in their environment by inducing regulatory networks controlling the expression and activity of cytochrome P450 monooxygenase (P450s) detoxificative enzymes. In particular, black swallowtail (Papilio polyxenes) caterpillars respond to xanthotoxin, a toxic phytochemical in their hostplants, by activating transcription of the CYP6B1 promoter via several regions located within 150 nt of the transcription initiation site. One such element is the xenobiotic response element to xanthotoxin (XRE–Xan) that lies upstream of consensus XRE–AhR (xenobiotic response element to the aryl hydrocarbon receptor) and OCT-1 (octamer-1 binding site) element known to be utilized in mammalian aryl hydrocarbon response cascades. Two-plasmid transfections conducted in Sf9 cells have indicated that XRE–Xan, XRE–AhR and a number of other proximal elements, but not OCT-1, are critical for basal as well as xanthotoxin- and benzo[α]pyrene-induced transcription of the CYP6B1 promoter. Four-plasmid transfections with vectors co-expressing the spineless (Ss) and tango (Tgo) proteins, the Drosophila melanogaster homologues of mammalian AhR and ARNT, have indicated that these proteins enhance basal expression of the CYP6B1 promoter but not the magnitude of its xanthotoxin and benzo[α]pyrene induction. Based on these results, we propose that these Drosophila transcription factors modulate basal expression of this promoter in a ligand-independent manner and attenuate its subsequent responses to planar aryl hydrocarbons (benzo[α]pyrene) and allelochemicals (xanthotoxin). [Copyright &y& Elsevier]

The formation of different structures in Drosophila depends on the combined activities of selector genes and signaling pathways. For instance, the antenna requires the selector gene homothorax, which distinguishes between the leg and the antenna and can specify distal antenna if expressed ectopically. Similarly, the eye is formed by a group of “eye-specifying” genes, among them eyeless, which can direct eye development ectopically. We report here the characterization of the hernandez and fernandez genes, expressed in the antennal and eye primordia of the eye–antenna imaginal disc. The predicted proteins encoded by these two genes have 27% common amino acids and include a Pipsqueak domain. Reduced expression of either hernandez or fernandez mildly affects antenna and eye development, while the inactivation of both genes partially transforms distal antenna into leg. Ectopic expression of either of the two genes results in two different phenotypes: it can form distal antenna, activating genes like homothorax, spineless, and spalt, and it can promote eye development and activates eyeless. Reciprocally, eyeless can induce hernandez and fernandez expression, and homothorax and spineless can activate both hernandez and fernandez when ectopically expressed. The formation of eye by these genes seems to require Notch signaling, since the induction of ectopic eyes and the activation of eyeless by the hernandez gene are suppressed when the Notch function is compromised. Our results show that the hernandez and fernandez genes are required for antennal and eye development and are also able to specify eye or antenna ectopically. [Copyright &y& Elsevier]

The article features the nightfall thornless trailing blackberry variety from the U.S. Department of Agriculture-Agricultural Research Service breeding program in Corvallis, Oregon. It has yields and fruit quality similar to the Marion variety. Its plants are thornless and adapted to machine harvesting.

The article presents information on the Black Pearl thornless trailing blackberry variety from the U.S. Department of Agricultural Research Service breeding program. It has a significant yield in Oregon similar to all of the varieties tested. Harvesting of the Black Pearl begins in the first few days of July and peaks by the third week.

Development requires highly coordinated changes in chromatin accessibility in order for proper gene regulation to occur. Here, we identify factors associated with major, discrete changes in chromatin accessibility during butterfly wing metamorphosis. By combining mRNA sequencing (mRNA-seq), assay for transposase-accessible chromatin using sequencing (ATAC-seq), and machine learning analysis of motifs, we show that distinct sets of transcription factors are predictive of chromatin opening at different developmental stages. Our data suggest an important role for nuclear hormone receptors early in metamorphosis, whereas PAS-domain transcription factors are strongly associated with later chromatin opening. Chromatin immunoprecipitation sequencing (ChIP-seq) validation of select candidate factors showed spineless binding to be a major predictor of opening chromatin. Surprisingly, binding of ecdysone receptor (EcR), a candidate accessibility factor in Drosophila , was not predictive of opening but instead marked persistent sites. This work characterizes the chromatin dynamics of insect wing metamorphosis, identifies candidate chromatin remodeling factors in insects, and presents a genome assembly of the model butterfly Junonia coenia. • Chromatin accessibility during butterfly wing development is highly dynamic • Different sets of transcription factors associate with accessibility at different stages • ChIP-seq indicates spineless binding predicts changes in accessibility • Assembly and annotation of the Junonia coenia genome are provided Using ATAC-seq, van der Burg et al. show that chromatin organization during butterfly wing development is highly dynamic. Motif enrichment analysis followed by ChIP-seq shows that DNA binding of transcription factor spineless, but not EcR, is strongly associated with opening chromatin. [ABSTRACT FROM AUTHOR]

Each individual perceives the world in a unique way, but little is known about the genetic basis of variation in sensory perception. In the fly eye, the random mosaic of color-detecting R7 photoreceptor subtypes is determined by stochastic on/off expression of the transcription factor Spineless (Ss). In a genome-wide association study, we identified a naturally occurring insertion in a regulatory DNA element in ss that lowers the ratio of Ss ON to Ss OFF cells. This change in photoreceptor fates shifts the innate color preference of flies from green to blue. The genetic variant increases the binding affinity for Klumpfuss (Klu), a zinc finger transcriptional repressor that regulates ss expression. Klu is expressed at intermediate levels to determine the normal ratio of Ss ON to Ss OFF cells. Thus, binding site affinity and transcription factor levels are finely tuned to regulate stochastic expression, setting the ratio of alternative fates and ultimately determining color preference.

The Drosophila adult head mostly derives from the composite eye-antenna imaginal disc. The antennal disc gives rise to two adult olfactory organs: the antennae and maxillary palps. Here, we have analysed the regional specification of the maxillary palp within the antennal disc. We found that a maxillary field, defined by expression of the Hox gene Deformed, is established at about the same time as the eye and antennal fields during the L2 larval stage. The genetic program leading to maxillary regionalisation and identity is very similar to the antennal one, but is distinguished primarily by delayed prepupal expression of the ventral morphogen Wingless (Wg). We find that precociously expressing Wg in the larval maxillary field suffices to transform it towards antennal identity, whereas overexpressing Wg later in prepupae does not. These results thus indicate that temporal regulation of Wg is decisive to distinguishing maxillary and antennal organs. Wg normally acts upstream of the antennal selector spineless (ss) in maxillary development. However, mis-expression of Ss can prematurely activate wg via a positive-feedback loop leading to a maxillary-to-antenna transformation. We characterised: (1) the action of Wg through ss selector function in distinguishing maxillary from antenna; and (2) its direct contribution to identity choice. [ABSTRACT FROM AUTHOR]