Leaflet initiation is temporally and spatially separated in simple and complex tomato (Solanum lycopersicum) leaf mutants: a developmental analysis

Botany ◽  
2010 ◽  
Vol 88 (8) ◽  
pp. 710-724 ◽  
Author(s):  
Julie Kang ◽  
Neelima R. Sinha
Keyword(s):  
Histological Analysis ◽  
Wild Type ◽  
Knox Gene ◽  
Leaf Morphogenesis ◽  
Multiple Factors ◽  
Developmental Program ◽  
Meristematic Activity ◽  
Primary Leaflet ◽  
Developmental Analysis ◽  
Leaf Mutants

Formation of a compound leaf requires the involvement of multiple factors, including KNOX1 gene expression. To further characterize simple and complex tomato leaf mutants, we analyzed their morphology and development by assessing: leaf phenotypes, primary leaf morphogenesis, expression of the class I KNOX gene LeT6, and meristematic activity of the marginal blastozone. Mutants with alterations in lobing and (or) pinnation (decrease/increase) were analyzed. Primary leaflet initiation is delayed in mutants with decreased lobing. In contrast, leaflet initiation is advanced or similar to the wild type in mutants with deep lobes. Leaves with increased pinnation along the rachis require a protracted developmental program to form their final leaf morphology. Using a morphometric analysis, we show that leaf complexity can be quantified. The expression pattern of LeT6 correlates with histological analysis of meristematic activity of the marginal blastozone, suggesting that LeT6 may play a role, through some unknown mechanism, to regulate meristematic competence, not only in the marginal blastozone to regulate leaflet lobing, but along the entire length of the leaf to regulate pinnation in compound leaves.

scholarly journals Mutator-Suppressible Alleles of rough sheath1 and liguleless3 in Maize Reveal Multiple Mechanisms for Suppression

Genetics ◽  
2000 ◽  
Vol 154 (1) ◽  
pp. 437-446 ◽  
Author(s):  
Lisa Girard ◽  
Michael Freeling
Keyword(s):  
Untranslated Region ◽  
Mutant Allele ◽  
Negative Regulation ◽  
Wild Type ◽  
Knox Gene ◽  
Transcript Accumulation ◽  
Mu Suppression ◽  
Different Types ◽  
Rna Blot Analysis

Abstract Insertions of Mutator transposons into maize genes can generate suppressible alleles. Mu suppression is when, in the absence of Mu activity, the phenotype of a mutant allele reverts to that of its progenitor. Here we present the characterization of five dominant Mu-suppressible alleles of the knox (knotted1-like homeobox) genes liguleless3 and rough sheath1, which exhibit neomorphic phenotypes in the leaves. RNA blot analysis suggests that Mu suppression affects only the neomorphic aspect of the allele, not the wild-type aspect. Additionally, Mu suppression appears to be exerting its effects at the level of transcription or transcript accumulation. We show that truncated transcripts are produced by three alleles, implying a mechanism for Mu suppression of 5′ untranslated region insertion alleles distinct from that which has been described previously. Additionally, it is found that Mu suppression can be caused by at least three different types of Mutator elements. Evidence presented here suggests that whether an allele is suppressible or not may depend upon the site of insertion. We cite previous work on the knox gene kn1, and discuss our results in the context of interactions between Mu-encoded products and the inherently negative regulation of neomorphic liguleless3 and rough sheath1 transcription.

scholarly journals Extended expression of MaKN1 contributes to the leaf morphology in aquatic forms of Myriophyllum aquaticum

Botany ◽  
2015 ◽  
Vol 93 (9) ◽  
pp. 611-621
Author(s):  
M.D. Shafiullah ◽  
Christian R. Lacroix
Keyword(s):  
Apical Meristem ◽  
Leaf Morphology ◽  
Expression Patterns ◽  
Homeobox Gene ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Myriophyllum Aquaticum ◽  
Knox Gene ◽  
Leaf Morphogenesis

Myriophyllum aquaticum (Vell.) Verdc. is heterophyllous in nature with highly dissected simple leaves consisting of several lobes. KNOX (KNOTTED1-LIKE HOMEOBOX) genes are believed to have played an important role in the evolution of leaf diversity. Up-regulation of KNOX during leaf primordium initiation can lead to leaf dissection in plants with simple leaves and, if overexpressed, can produce ectopic meristems on leaves. A previous study on KNOX gene expression in the aerial form of this species showed that this gene is expressed in the shoot apical meristem (SAM), as well as in leaf primordia P0 to P8. Based on these results, it was hypothesized that the prolonged expression of the MaKN1 (Myriophyllum aquaticum Knotted1-like homeobox) gene beyond P8, might play an important role in the generation of more lobes, longer lobes, and hydathode formation in the aquatic leaves of M. aquaticum. The technique of in situ hybridization was carried out using a previously sequenced 300 bp fragment of MaKN1 to determine the expression patterns of this gene in the shoot of aquatic forms of the plant. Expression patterns of MaKN1 revealed that the SAM and leaf primordia of aquatic forms of M. aquaticum at levels P0 (youngest) to P4 were distributed throughout these structures. The level of expression of this MaKN1 gene progressively became more localized to lobes in older leaf primordia (levels P5 to P12). Previous studies of aerial forms of this plant showed MaKN1 expression until P8. Our results with aquatic forms show that the highly dissected leaf morphology in aquatic forms was the result of the prolonged expression of MaKN1 beyond P8. This resulted in the formation of elongated and slightly more numerous lobes, and hydathodes in aquatic forms. These findings support the view that KNOX genes are important developmental regulators of leaf morphogenesis and have played an important role in the evolution of leaf forms in the plant kingdom.

Different roles for Pax6 in the optic vesicle and facial epithelium mediate early morphogenesis of the murine eye

Development ◽  
2000 ◽  
Vol 127 (5) ◽  
pp. 945-956 ◽  
Author(s):  
J.M. Collinson ◽  
R.E. Hill ◽  
J.D. West
Keyword(s):  
Histological Analysis ◽  
Eye Development ◽  
Wild Type Mouse ◽  
Lens Epithelium ◽  
Optic Vesicle ◽  
Wild Type ◽  
Adhesive Properties ◽  
Optic Vesicles ◽  
Lens Placode ◽  
Mutant Cells

Chimaeric mice were made by aggregating Pax6(−/−) and wild-type mouse embryos, in order to study the interaction between the optic vesicle and the prospective lens epithelium during early stages of eye development. Histological analysis of the distribution of homozygous mutant cells in the chimaeras showed that the cell-autonomous removal of Pax6(−/−) cells from the lens, shown previously at E12.5, is nearly complete by E9.5. Most mutant cells are eliminated from an area of facial epithelium wider than, but including, the developing lens placode. This result suggests a role for Pax6 in maintaining a region of the facial epithelium that has the tissue competence to undergo lens differentiation. Segregation of wild-type and Pax6(−/−) cells occurs in the optic vesicle at E9.5 and is most likely a result of different adhesive properties of wild-type and mutant cells. Also, proximo-distal specification of the optic vesicle (as assayed by the elimination of Pax6(−/−) cells distally), is disrupted in the presence of a high proportion of mutant cells. This suggests that Pax6 operates during the establishment of patterning along the proximo-distal axis of the vesicle. Examination of chimaeras with a high proportion of mutant cells showed that Pax6 is required in the optic vesicle for maintenance of contact with the overlying lens epithelium. This may explain why Pax6(−/−) optic vesicles are inefficient at inducing a lens placode. Contact is preferentially maintained when the lens epithelium is also wild-type. Together, these results demonstrate requirements for functional Pax6 in both the optic vesicle and surface epithelia in order to mediate the interactions between the two tissues during the earliest stages of eye development.

scholarly journals The temporal transcription factor E93 controls dynamic enhancer activity and chromatin accessibility during development

2019 ◽  
Author(s):  
Spencer L. Nystrom ◽  
Matthew J. Niederhuber ◽  
Daniel J. McKay
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Developmental Time ◽  
Chromatin Accessibility ◽  
Wild Type ◽  
Spatial Cues ◽  
Enhancer Activity ◽  
Temporal Gene Expression ◽  
Developmental Program ◽  
Temporal Cues

ABSTRACTHow temporal cues combine with spatial inputs to control gene expression during development is poorly understood. Here, we test the hypothesis that the Drosophila transcription factor E93 controls temporal gene expression by regulating chromatin accessibility. Precocious expression of E93 early in wing development reveals that it can simultaneously activate and deactivate different target enhancers. Notably, the precocious patterns of enhancer activity resemble the wild-type patterns that occur later in development, suggesting that provision of E93 alters the competence of enhancers to respond to spatial cues. Genomic profiling reveals that precocious E93 expression is sufficient to regulate chromatin accessibility at a subset of its targets. These accessibility changes mimic those that normally occur later in development, indicating that precocious E93 accelerates the wild-type developmental program. Further, we find that target enhancers that do not respond to precocious E93 in early wings become responsive after a developmental transition, suggesting that parallel temporal pathways work alongside E93. These findings support a model wherein E93 expression functions as an instructive cue that defines a broad window of developmental time through control of chromatin accessibility.

scholarly journals The Meningococcal ABC-Type l-Glutamate Transporter GltT Is Necessary for the Development of Experimental Meningitis in Mice

2009 ◽  
Vol 77 (9) ◽  
pp. 3578-3587 ◽  
Author(s):  
Roberta Colicchio ◽  
Susanna Ricci ◽  
Florentia Lamberti ◽  
Caterina Pagliarulo ◽  
Chiara Pagliuca ◽  
...  
Keyword(s):  
Histological Analysis ◽  
Glutamate Uptake ◽  
Glutamate Transporter ◽  
Systemic Infection ◽  
Fold Increase ◽  
Wild Type ◽  
Nutrient Source ◽  
Infectious Dose ◽  
Life Threatening ◽  
The Brain

ABSTRACT Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type l-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use l-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.

Two independent and polarized processes of cell elongation regulate leaf blade expansion in Arabidopsis thaliana (L.) Heynh

Development ◽  
1996 ◽  
Vol 122 (5) ◽  
pp. 1589-1600 ◽  
Author(s):  
T. Tsuge ◽  
H. Tsukaya ◽  
H. Uchimiya
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Elongation ◽  
Leaf Development ◽  
Cellular Level ◽  
Leaf Length ◽  
Specific Cell ◽  
Wild Type ◽  
Leaf Morphogenesis ◽  
Length Direction ◽  
Number Of Cells

For genetic analysis of mechanisms of leaf morphogenesis, we chose Arabidopsis thaliana (L.) Heynh. as a model for leaf development in dicotyledonous plants. Leaves of the angustifolia mutant were the same length as but narrower and thicker than wild-type leaves. The total number of cells in leaf blades of angustifolia plants was the same as in the wild type. At the cellular level in the angustifolia mutant it was found that the cells were smaller in the leaf-width direction and larger in the leaf-thickness direction than in wild type, revealing the function of the ANGUSTIFOLIA gene, which is to control leaf morphology by regulating polarity-specific cell elongation. The existence of similar genes that regulate leaf development in the length direction was, therefore, predicted. Three loci and several alleles associated with short-leaved mutants were newly isolated as rotundifolia mutants. The rotundifolia3 mutant had the same number of cells as the wild type, with reduced cell elongation in the leaf-length direction. The features of the angustifolia rotundifolia3 double mutant indicated that ANGUSTIFOLIA and ROTUNDIFOLIA3 genes act independently. We propose that leaf expansion in Arabidopsis involves at least two independent developmental processes: width development and length development, with the ANGUSTIFOLIA and ROTUNDIFOLIA3 genes playing different polarity-specific roles in cell elongation.

Frontline Therapy forBRAF-Mutated Metastatic Melanoma: How Do You Choose, and Is There One Correct Answer?

2019 ◽  
pp. 564-571 ◽  
Author(s):  
Anna C. Pavlick ◽  
Leslie Fecher ◽  
Paolo A. Ascierto ◽  
Ryan J. Sullivan
Keyword(s):  
Targeted Therapy ◽  
Metastatic Melanoma ◽  
Initial Therapy ◽  
Combination Immunotherapy ◽  
Wild Type ◽  
Aggressive Disease ◽  
Multiple Factors ◽  
Secondary Endpoints ◽  
Frontline Therapy ◽  
Mutation Braf

Genetic analysis of melanoma has allowed us to identify a population of patients who have more aggressive disease and harbor the driver mutation BRAF. This mutation is found in approximately 50% of metastatic disease and provides a target for focused therapies to control this disease. These responses are usually brisk; however, they lack the durability of immunotherapy. Frontline therapy for patients with BRAF-mutated melanoma is not as straightforward as prescribing BRAF/MEK inhibitors. Prior trials of combination immunotherapy demonstrate similar responses and durability of responses in patients with BRAF wild-type as well as BRAF-mutated disease. Decisions about immunotherapy, targeted therapy, or the combination of immunotherapy with targeted therapy require an oncologist to evaluate multiple factors to select which treatment option is best for the patient. Trials for metastatic melanoma have included biomarkers as secondary endpoints and aim to identify some way to predict a response, or lack thereof, to therapy. Here, we discuss the utility and reliability of biomarkers in determining therapy for patients with BRAF-mutated metastatic melanoma and discuss combination immunotherapy with targeted therapy versus sequential immunotherapy/targeted therapy as well as which regimen should be implemented as initial therapy.

scholarly journals Hyperhomocysteinemia and Dyslipidemia in point mutation G307S of cystathionine β-synthase-deficient rabbit generated using CRISPR/Cas9

2020 ◽  
Author(s):  
Ting Zhang ◽  
Rui Lu ◽  
Yibing Chen ◽  
Yuguo Yuan ◽  
Shaozheng Song ◽  
...  
Keyword(s):  
Point Mutation ◽  
Plasma Levels ◽  
Lipid Droplets ◽  
Histological Analysis ◽  
Rabbit Model ◽  
Causative Factor ◽  
Normal Diet ◽  
Vitamin B ◽  
Wild Type ◽  
Rabbit Embryos

Abstract Background: Congenital hyper-homocysteinemia (HHcy) is caused by a defective cystathionine β-synthase (CBS) gene, and is frequently associated with dyslipdemia. The aim of this study was to further elucidate the effect of mutated CBS gene on circulating lipids using a rabbit model harboring a homozygous G307S point mutation in CBS.Methods: CRISPR/Cas9 system was used in rabbit embryos to edit their CBS gene. The founder rabbits were sequenced, and their plasma Hcy and lipid profile were analyzed. Results: Six CBS-KO founder lines with biallelic modifications were obtained. Mutation in CBS caused significant growth retardation and high mortality rates within 6 weeks after birth. In addition, the 6-week old CBS-KO rabbits showed higher plasma levels of Hcy, TG, TC and LDL-C compared to the age-matched wild-type (WT) controls. Histological analysis of the mutants showed accumulation of micro-vesicular cytoplasmic lipid droplets in the hepatocytes. However, gastric infusion of vitamin B and betaine complex significantly decreased the plasma levels of TG, TC and LDL-C in the CBS-KO rabbits, as well as hepatic steatosis compared to the untreated animals. Conclusion: We generated CBSG307S rabbit model that exhibited severe dyslipidemia when fed on a normal diet, indicating that G307S mutation in the CBS gene is a causative factor for dyslipidemia.

252. Morphometric and histological analysis of ovaries from sheep heterozygous for the prolific woodlands allele

2005 ◽  
Vol 17 (9) ◽  
pp. 101
Author(s):  
E. S. Feary ◽  
J. L. Juengel ◽  
P. Smith ◽  
A. R. O'Connell ◽  
G. H. Davis ◽  
...  
Keyword(s):  
Histological Analysis ◽  
Follicular Development ◽  
Wild Type ◽  
Preantral Follicles ◽  
Antral Follicles ◽  
Mechanistic Pathway ◽  
Morphometric Methods ◽  
The Mean ◽  
Large Ovary

Woodlands are a line of Coopworth sheep with a novel, imprinted X-linked fecundity allele resulting in ovulation rates about 0.40 higher than wild-type animals. Daughters of progeny tested sires with and without the gene were studied. Previously, lambs heterozygous for the Woodlands allele were found to have larger ovaries and more antral (i.e. type 5) but not preantral (i.e. types 1–4) follicles than in wild-type contemporaries. The large ovary phenotype was found to be transient and was absent after puberty. However, based on follow-up studies it was evident that the large ovary phenotype was not strongly associated with the Woodlands fecundity allele. Thus, it was uncertain whether animals carrying the Woodlands gene had different follicular populations compared to wild-type controls. To address this question, follicular populations were compared in adult ewes heterozygous for the Woodlands allele with age-matched controls. Using standard morphometric methods and histological analysis, no differences were observed in the mean numbers of types 1, 1a, 2, 3 and 4 preantral follicles between the genotypes. Furthermore, no differences were observed between genotypes in follicular or oocyte diameters for any follicular type. The adult Woodlands carrier ewes had twice as many small type 5 follicles (< 1mm) when compared to wild-type contemporaries although no difference was seen in the numbers of antral follicles > 1mm in diameter. In addition, antrum formation occurred at a smaller follicular diameter in the heterozygous Woodlands animals. Therefore, the increased number of antral follicles observed in both lambs and adult ewes suggests that this difference in pattern of follicular development is associated with the X-linked fecundity allele. This novel phenotype of early antrum formation and larger number of small preantral follicles differs from that observed in sheep with the Inverdale or Booroola mutations, suggesting that a different mechanistic pathway is involved. Acknowledgements: The Marsden Fund, FRST and Ovita.

Developmental characterization and chromosomal mapping of the 5-azacytidine-sensitive fluF locus of Aspergillus nidulans

1988 ◽  
Vol 8 (8) ◽  
pp. 3043-3050
Author(s):  
M Tamame ◽  
F Antequera ◽  
E Santos
Keyword(s):  
Aspergillus Nidulans ◽  
Nuclear Gene ◽  
Chromosomal Mapping ◽  
Mutagenic Action ◽  
Primary Role ◽  
Wild Type ◽  
Significant Frequency ◽  
Developmental Program ◽  
Low Concentrations ◽  
The Right

In Aspergillus nidulans, a fungus that possesses negligible, if any, levels of methylation in its genome, low concentrations of 5-azacytidine (5-AC) convert a high percentage of the cell population to fluffy phenotypic variants through a heritable modification of a single nuclear gene (M. Tamame, F. Antequera, J. R. Villanueva, and T. Santos, Mol. Cell. Biol. 3:2287-2297, 1983). This new 5-AC-altered locus, designated here fluF1, was mapped as the closest marker to the centromere that has been identified so far on the right arm of chromosome VIII. Of all mutagens tested, only 5-AC induced the fluffy phenotype with a significant frequency. Furthermore, we determined that the wild-type, dominant allele of the fluF gene was primarily accessible to modification by 5-AC at the initial stages of fungal vegetative growth. These results indicated that 5-AC does not act through random mutagenic action but, rather, that fluF constitutes a specific target for this drug during a well-defined period of fungal development. Alteration of fluF by 5-AC resulted in a dramatic modification of the developmental program of A. nidulans. The resulting fluffy clones were characterized by massive, uncontrolled proliferation of undifferentiated hyphae, a drastic delay in the onset of asexual differentiation (conidiation), and colonies with an invasive nature. These features are reminiscent of the malignant properties of tumor cells. We propose that the locus fluF plays a primary role in the control of cell proliferation in A. nidulans and that its alteration by 5-AC produces pleiotropic modifications of the developmental program of this fungus.

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