The floral development and anatomy of Carica papaya (Caricaceae)

1999 ◽  
Vol 77 (4) ◽  
pp. 582-598 ◽  
Author(s):  
LP Ronse Decraene ◽  
E F Smets
Keyword(s):  
Calcium Oxalate ◽  
Carica Papaya ◽  
Floral Development ◽  
Floral Anatomy ◽  
Structural Basis ◽  
Unisexual Flowers ◽  
Stigmatic Exudate ◽  
Large Ovary ◽  
Further Development ◽  
Shed Light

Floral development and anatomy of Carica papaya L. have been investigated to shed light on (i) the morphology of the flower, (ii) the structural basis for the pollination mechanism, and (iii) the relationships of the Caricaceae. Carica is mostly dioecious with a strong dimorphism between staminate and pistillate flowers. The development of staminate flowers resembles that of pistillate flowers up to the initiation of the stamens. Further development leads to highly diverging morphologies. In staminate flowers a combination of contorted growth and the development of a common stamen-petal tube produces a long floral tube. The gynoecium grows into a central spearlike pistillode. The pistillate flowers have no traces of stamens and initiate five antesepalous carpel primordia. Common basal growth leads to the development of a large ovary with staglike stigmatic lobes and intruding placentae covered with numerous ascending ovules. Floral anatomy of staminate and pistillate flowers is described. The nature of the colleters is discussed. The morphological basis for reward production in C. papaya is clarified, and conflicting views on pollination are discussed. Nectaries of staminate flowers are located on the central rudimentary pistil and not at the base of the stamens, as previously reported. The anthers contain packages of calcium oxalate crystals. Pistillate flowers produce no nectar but have a stigmatic exudate. We compared the floral development and anatomy of Carica with that of Adenia (Passifloraceae) and Moringa (Moringaceae) in the view of a relationship with other glucosinolate-producing families. Although a derivation of the unisexual flowers from bisexual ancestors is probable, Storey's hypothetical derivation of pistillate flowers is not supported by the floral ontogeny and vasculature.Key words: Adenia, Caricaceae, Moringa anatomy, calcium oxalate packages, dioecy, floral structure, nectaries, ontogeny, pollination, systematic relationships.

scholarly journals Structural Basis for Linezolid Binding Site Rearrangement in the Staphylococcus aureus Ribosome

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Matthew J. Belousoff ◽  
Zohar Eyal ◽  
Mazdak Radjainia ◽  
Tofayel Ahmed ◽  
Rebecca S. Bamert ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Structural Information ◽  
Structural Basis ◽  
Common Mechanism ◽  
Resistance Mutations ◽  
Antimicrobial Drugs ◽  
Linezolid Resistance ◽  
Drug Modification ◽  
Antibiotic Resistance Mutations ◽  
Shed Light

ABSTRACT An unorthodox, surprising mechanism of resistance to the antibiotic linezolid was revealed by cryo-electron microscopy (cryo-EM) in the 70S ribosomes from a clinical isolate of Staphylococcus aureus. This high-resolution structural information demonstrated that a single amino acid deletion in ribosomal protein uL3 confers linezolid resistance despite being located 24 Å away from the linezolid binding pocket in the peptidyl-transferase center. The mutation induces a cascade of allosteric structural rearrangements of the rRNA that ultimately results in the alteration of the antibiotic binding site. IMPORTANCE The growing burden on human health caused by various antibiotic resistance mutations now includes prevalent Staphylococcus aureus resistance to last-line antimicrobial drugs such as linezolid and daptomycin. Structure-informed drug modification represents a frontier with respect to designing advanced clinical therapies, but success in this strategy requires rapid, facile means to shed light on the structural basis for drug resistance (D. Brown, Nat Rev Drug Discov 14:821–832, 2015, https://doi.org/10.1038/nrd4675 ). Here, detailed structural information demonstrates that a common mechanism is at play in linezolid resistance and provides a step toward the redesign of oxazolidinone antibiotics, a strategy that could thwart known mechanisms of linezolid resistance. IMPORTANCE The growing burden on human health caused by various antibiotic resistance mutations now includes prevalent Staphylococcus aureus resistance to last-line antimicrobial drugs such as linezolid and daptomycin. Structure-informed drug modification represents a frontier with respect to designing advanced clinical therapies, but success in this strategy requires rapid, facile means to shed light on the structural basis for drug resistance (D. Brown, Nat Rev Drug Discov 14:821–832, 2015, https://doi.org/10.1038/nrd4675 ). Here, detailed structural information demonstrates that a common mechanism is at play in linezolid resistance and provides a step toward the redesign of oxazolidinone antibiotics, a strategy that could thwart known mechanisms of linezolid resistance.

scholarly journals Surgical techniques: past, present and future

2012 ◽  
Vol 2 (1) ◽  
pp. 9 ◽  
Author(s):  
Karim Qayumi
Keyword(s):  
Middle Ages ◽  
Technological Progress ◽  
Surgical Techniques ◽  
Neolithic Period ◽  
Minimally Invasive Surgical ◽  
Surgical Methods ◽  
Modern Hospital ◽  
The 19Th Century ◽  
Further Development ◽  
Shed Light

The aim of this paper is to provide an analytical survey of the information available on the development of past and present surgical techniques, and to make projections for the future. For the purposes of this paper, the <em>Past</em> starts in the Neolithic period and ends in the 1800s. In this context, I have divided the <em>Past</em> into <em>Prehistoric</em>, <em>Ancient</em> and <em>Middle Ages</em>, and this period ends in the second half of the 19th century when the major obstacles to the further development of surgery, such as overcoming pain and infection, were removed. We will discuss the development of surgical techniques, and the obstacles and opportunities prevalent in these periods. In the context of this paper, the <em>Present</em> begins in 1867, when Louis Pasteur discovered microorganisms, and ends in the present day. There have been many important changes in the development of surgical techniques during this period, such as the transfer of surgery from the unsterile operating room to the modern hospital operating theater, the development of advanced and specialized surgical practices, such as transplants and laparoscopy, and minimally invasive surgical methods, robotic and Natural Orifice Transluminal Endoscopic Surgery. It is very difficult to foresee how surgical techniques will develop in the <em>Future</em> because of the unpredictable nature of technological progress. Therefore, in this paper, the forecast for the <em>Future</em> is limited to the next 50- 100 years and is a realistic calculation based on already existing technologies. In this context, the <em>Future</em> is divided into the development of surgical techniques that will develop in the <em>near</em> and <em>distant</em> future. It is anticipated that this overview will shed light on the historical perspective of surgical techniques and stimulate interest in their further development.

Floral development and anatomy of Macarthuria australis (Macarthuriaceae): key to understanding the unusual initiation sequence of Caryophyllales

2019 ◽  
Author(s):  
Louis P. Ronse De Craene ◽  
Lai Wei
Keyword(s):  
Floral Development ◽  
Floral Anatomy ◽  
Floral Evolution ◽  
Flower Initiation ◽  
Developmental Sequence ◽  
Petal Development ◽  
Initiation Sequence ◽  
Rapid Emergence

We investigated the floral anatomy and development of Macarthuria australis Hügel ex Endl., an unusual genus endemic to Australia, in the context of floral evolution of core Caryophyllales. Flower initiation is spiral, with sepals developing quincuncially. The first two petals continue the sequence of sepal initiation, but the remaining petals arise from common stamen–petal primordia. The androecium develops sequentially as three inner antesepalous and five outer antepetalous stamens. The globular ovary is trimerous with a short symplicate zone and two arillate ovules per locule. The rapid emergence of the androecium leads to a partial absorption of the petal primordia within the androecial tissue. The two first-formed petals have more room for development and precede the androecium, supporting the fact that petals are not staminodial in origin. This heterochronic shift correlates with an inversed developmental sequence of the antesepalous stamens. The constraint caused by the spatial occupation of sepals and carpels leads to the loss of two stamens, and the re-arrangement of stamens and petals along the flanks of the carpels. The floral development of Macarthuria anticipates a syndrome of stamen and petal development in other core Caryophyllales and culminating in the Caryophyllaceae.

scholarly journals Structural basis for carotenoid cleavage by an archaeal carotenoid dioxygenase

2020 ◽  
Vol 117 (33) ◽  
pp. 19914-19925 ◽  
Author(s):  
Anahita Daruwalla ◽  
Jianye Zhang ◽  
Ho Jun Lee ◽  
Nimesh Khadka ◽  
Erik R. Farquhar ◽  
...  
Keyword(s):  
Active Site ◽  
Molecular Basis ◽  
Structural Basis ◽  
Reaction Intermediates ◽  
Catalytic Activities ◽  
Selective Stabilization ◽  
Carotenoid Cleavage Dioxygenases ◽  
Active Site Cavity ◽  
Binding Cleft ◽  
Shed Light

Apocarotenoids are important signaling molecules generated from carotenoids through the action of carotenoid cleavage dioxygenases (CCDs). These enzymes have a remarkable ability to cleave carotenoids at specific alkene bonds while leaving chemically similar sites within the polyene intact. Although several bacterial and eukaryotic CCDs have been characterized, the long-standing goal of experimentally visualizing a CCD–carotenoid complex at high resolution to explain this exquisite regioselectivity remains unfulfilled. CCD genes are also present in some archaeal genomes, but the encoded enzymes remain uninvestigated. Here, we address this knowledge gap through analysis of a metazoan-like archaeal CCD fromCandidatusNitrosotalea devanaterra (NdCCD).NdCCD was active toward β-apocarotenoids but did not cleave bicyclic carotenoids. It exhibited an unusual regiospecificity, cleaving apocarotenoids solely at the C14′–C13′ alkene bond to produce β-apo-14′-carotenals. The structure ofNdCCD revealed a tapered active site cavity markedly different from the broad active site observed for the retinal-formingSynechocystisapocarotenoid oxygenase (SynACO) but similar to the vertebrate retinoid isomerase RPE65. The structure ofNdCCD in complex with its apocarotenoid product demonstrated that the site of cleavage is defined by interactions along the substrate binding cleft as well as selective stabilization of reaction intermediates at the scissile alkene. These data on the molecular basis of CCD catalysis shed light on the origins of the varied catalytic activities found in metazoan CCDs, opening the possibility of modifying their activity through rational chemical or genetic approaches.

The floral development and floral anatomy ofChrysosplenium alternifolium, an unusal member of the Saxifragaceae

1998 ◽  
Vol 111 (4) ◽  
pp. 573-580 ◽  
Author(s):  
L. P. Ronse Decraene ◽  
P. Roels ◽  
E. F. Smets ◽  
A. Backlund
Keyword(s):  
Floral Development ◽  
Floral Anatomy

Developmental morphology of the flower of Anthurium jenmanii: a new element in our understanding of basal Araceae

Botany ◽  
2008 ◽  
Vol 86 (1) ◽  
pp. 45-52 ◽  
Author(s):  
Denis Barabé ◽  
Christian Lacroix
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Floral Development ◽  
Developmental Morphology ◽  
Calcium Oxalate Crystals ◽  
Stages Of Development ◽  
Early Stages ◽  
Floral Primordia ◽  
Scanning Electron

The early stages of development of the inflorescence of Anthurium jenmanii Engl. were examined using scanning electron microscopy. The inflorescence of A. jenmanii consists of more than 100 flowers arranged in recognizable spirals. Each flower has four broad tepals enclosing four stamens that are not visible prior to anthesis. The gynoecium consists of two carpels. The floral primordia are first initiated on the lower portion of the inflorescence, they then increase in size and appear as transversely extended bulges. The two lateral tepals are the first organs to be initiated, followed shortly thereafter by the two median tepals. The two lateral stamens are initiated first, directly opposite the lateral tepals, and are followed by two median stamens initiated directly opposite the median tepals. A two-lobed stigma is clearly visible during the early stages of development of the gynoecium. On some of the young inflorescences, all floral parts were covered by extracellular calcium oxalate crystals. The release of these prismatic crystals occurs before the stamens and petals have reached maturity. The mode of floral development observed in Anthurium has similarities with that reported for Gymnostachys . However, contrary to Gymnostachys, the development of the flower of A. jenmanii is not unidirectional.

scholarly journals НАЗВАНИЯ МОЛОЧНЫХ ПРОДУКТОВ В ХАЛХА-МОНГОЛЬСКОМ, БУРЯТСКОМ И КАЛМЫЦКОМ ЯЗЫКАХ

2020 ◽  
Author(s):  
Valentin Rassadin ◽  
Svetlana Trofimova
Keyword(s):  
Dairy Products ◽  
Dairy Farming ◽  
Cattle Breeding ◽  
Dairy Food ◽  
Sour Milk ◽  
Dairy Cattle Breeding ◽  
Turkic Languages ◽  
The Republic ◽  
Further Development ◽  
Shed Light

Проведен сравнительный анализ лексики, относящейся к группе молочных продуктов питания, традиционных для кочевых скотоводческих народов Центральной Азии – халха-монголов, бурят и ойратов, а также и калмыков. Материалом исследования послужили современные монгольские языки, а также материалы диалектологических экспедиций, проведенных Валентином Ивановичем Рассадиным с 1970-х годов по 2000-е годы на территории Республики Бурятия, Западной Монголии. Все монгольские народы продолжают традиционно разводить пять видов скота – лошади, коровы, овцы, козы и верблюды, от которых получают молоко, как исходный продукт для приготовления самых разнообразных молочных блюд путём сквашивания, перегонки, процеживания, отстаивания, кипячения, высушивания или разбавления чаем или водой. Удалось выяснить, что молочное скотоводство и способы приготовления многих молочных продуктов пришли ещё к древним прамонголам из глубины веков вместе с названиями от древних тюрок и сохраняются у современных монгольских народов до сих пор. Рассматривая термины молочных продуктов в монгольских языках, приводится перечень терминов, представленных и в старописьменном монгольском языке, поскольку наличие в нем слов, имеющих полную аналогию современным терминам, свидетельствует об их древности в монгольских языках. Кроме того, приведенный перечень слов ярко свидетельствует, что термины молочного хозяйства давно сложились в монгольских языках, по всей видимости, еще в общемонгольскую эпоху, когда организовывалось молочное хозяйство у монгольских племен. Дальнейшая разработка этого пласта лексики, особенно в плане ее этимологизации, позволит пролить свет на внешнее влияние, особенно тюркских языков, при котором складывались термины молочных продуктов, поскольку ряд монгольских терминов имеет аналогии в тюркских языках, таких как: тюрк. süt – молоко, ajran – кислое молоко, qurut – сушеные сырки, bїšlaq – сыр домашнего приготовления, irimek – творожистая накипь на стенках котла от кипячения кислого молока, araqї – водка.A comparative analysis of vocabulary related to the group of dairy food products traditional for the nomadic cattle-breeding peoples of Central Asia – the Khalkha-Mongols, Buryats and Oirats, as well as Kalmyks. The research modern Mongolian languages, as well as materials of dialectological expeditions conducted by Valentin Ivanovich Rassadin from the 1970s to the 2000s in the Republic of Buryatia, Western Mongolia. All Mongolian peoples traditionally continue to breed five types of cattle – horses, cows, sheep, goats and camels, from which milk is obtained as a starting product for the preparation of a wide variety of dairy dishes by fermentation, distillation, straining, settling, boiling, drying or diluting with tea or water. It was possible to find out that dairy cattle breeding and methods of preparing many dairy products came to the ancient from the depths of centuries, along with the names from the ancient Turks and are still preserved among the modern Mongolian peoples. Considering the terms of dairy products in Mongolian languages, a list of terms in Mongolian language, have a complete analogy to modern. Above list of words clearly testifies that the terms of dairy farming have long been established in the Mongolian languages, most likely, back in the Mongolian era, when dairy farming was among the Mongol tribes. Further development of this layer of vocabulary, especially in terms of its, will shed light on the external influence, especially the Turkic languages, in which the terms of dairy products were formed, since a number of Mongolian terms have analogies in the Turkic languages, such as: turk. süt – milk, ajran – sour milk, qurut – dried cheeses, bїšlaq – home-made cheese, irimek – curd scum on the walls of the boiler from boiling sour milk, araqї – vodka.

scholarly journals Structural basis of ALC1/CHD1L autoinhibition and the mechanism of activation by the nucleosome

2021 ◽  
Author(s):  
zhucheng chen ◽  
li wang ◽  
kangjing chen
Keyword(s):  
Crystal Structure ◽  
Liver Cancer ◽  
Chromatin Remodeling ◽  
Structural Basis ◽  
Chromatin Remodeler ◽  
Macro Domain ◽  
Regulation Mechanisms ◽  
Shed Light ◽  
The Way

Chromatin remodeler ALC1 (amplification in liver cancer 1) is crucial for repairing damaged DNA. It is autoinhibited and activated by nucleosomal epitopes. However, the mechanisms by which ALC1 is regulated remain unclear. Here we report the crystal structure of human ALC1 and the cryoEM structure bound to the nucleosome. The structure shows the macro domain of ALC1 binds to lobe 2 of the ATPase motor, sequestering two elements for nucleosome recognition, explaining the autoinhibition mechanism of the enzyme. The H4 tail competes with the macro domain for lobe 2-binding, explaining the requirement for this nucleosomal epitope for ALC1 activation. A dual-arginine-anchor motif of ALC1 recognizes the acidic pocket of the nucleosome, which is critical for chromatin remodeling in vitro. Together, our findings illustrate the structures of ALC1 and shed light on its regulation mechanisms, paving the way for the discovery of drugs targeting ALC1 for the treatment of cancer.

scholarly journals Structural basis for histone variant H3tK27me3 recognition by PHF1 and PHF19

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Cheng Dong ◽  
Reiko Nakagawa ◽  
Kyohei Oyama ◽  
Yusuke Yamamoto ◽  
Weilian Zhang ◽  
...  
Keyword(s):  
Embryonic Stem ◽  
Structural Basis ◽  
Complex Structures ◽  
Polycomb Repressive Complex 2 ◽  
Tudor Domain ◽  
Histone H3k27 ◽  
Critical Components ◽  
Preferential Recognition ◽  
Shed Light

The Polycomb repressive complex 2 (PRC2) is a multicomponent histone H3K27 methyltransferase complex, best known for silencing the Hox genes during embryonic development. The Polycomb-like proteins PHF1, MTF2, and PHF19 are critical components of PRC2 by stimulating its catalytic activity in embryonic stem cells. The Tudor domains of PHF1/19 have been previously shown to be readers of H3K36me3 in vitro. However, some other studies suggest that PHF1 and PHF19 co-localize with the H3K27me3 mark but not H3K36me3 in cells. Here, we provide further evidence that PHF1 co-localizes with H3t in testis and its Tudor domain preferentially binds to H3tK27me3 over canonical H3K27me3 in vitro. Our complex structures of the Tudor domains of PHF1 and PHF19 with H3tK27me3 shed light on the molecular basis for preferential recognition of H3tK27me3 by PHF1 and PHF19 over canonical H3K27me3, implicating that H3tK27me3 might be a physiological ligand of PHF1/19.

Comparative morphology and ontogenetic patterns of Bdallophytum species (Cytinaceae, Malvales): insight into the biology of an endoparasitic genus

Botany ◽  
2020 ◽  
Author(s):  
Sandra Rios-Carrasco ◽  
SONIA VÁZQUEZ-SANTANA
Keyword(s):  
New World ◽  
Floral Development ◽  
Developmental Stages ◽  
Comparative Morphology ◽  
The Family ◽  
Unisexual Flowers ◽  
Male Flowers ◽  
And Bisexual ◽  
Early Developmental ◽  
Insight Into

Cytinaceae are root endoparasitic plants with only three genera. Their biology is largely unknown, and most knowledge of the family is based on the Old World genus, Cytinus. Here, we studied all three species of the New World Bdallophytum from Mexico. We describe their morphoanatomy, floral development, and embryology, highlighting the unique traits of Bdallophytum compared with two other genera of the family and members of Malvales. Both B. americanum and B. andrieuxii are dioecious, while B. oxylepis is gynomonoecious. The floral size and the number of floral organs vary within and among species, which appears common in Cytinaceae. The flowers of Bdallophytum exhibit synorganization in sexual organs, a synandrium in male flowers, and a gynostemium in bisexual flowers of B. oxylepis. Unisexual and bisexual flowers are zygomorphic at the early developmental stages. The unisexual flowers become actinomorphic in later development, while the bisexual flowers of B. oxylepis remain zygomorphic. The androecium of Bdallophytum has key traits shared with some Malvales, such as the fused filaments in Malvaceae and Sarcolaenaceae and the connective appendage shared with Dipterocarpaceae. Our results suggest that a unitegmic ovule is a unique trait for Bdallophytum. This is proposed here as a putative synapomorphy for Bdallophytum.

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