scholarly journals High-Order Organization of Guanine-Based Reflectors Underlies the Dual Functionality of the Fish Iris

2017 ◽  
Author(s):  
Dvir Gur ◽  
Jan-David Nicolas ◽  
Vlad Brumfeld ◽  
Omri Bar-Elli ◽  
Dan Oron ◽  
...  
Keyword(s):  
Developmental Stages ◽  
Optical Response ◽  
Underlying Mechanism ◽  
High Order ◽  
Dual Function ◽  
Light Barrier ◽  
Sem Imaging ◽  
Early Developmental ◽  
Shed Light

AbstractMany marine organisms have evolved a reflective iris to prevent unfocused light from reaching the retina. The fish iris has a dual function, both to camouflage the eye and serving as a light barrier. Yet, the mechanism that enables this dual functionality and the benefits of using a reflective iris have remained unclear. Using synchrotron micro-focused diffraction, cryo-SEM imaging and optical analyses on zebrafish at different stages of development, we show that the complex optical response of the iris is facilitated by the development a high-order organization of multilayered guanine-based crystal reflectors and pigments. We further demonstrate how the efficient light reflector is established during development to allow the optical functionality of the eye, already at early developmental stages. These results shed light on the evolutionary drive for developing a compact reflective iris, which is widely used by many animal species.Significance StatementThe fish iris is an exquisite example of nature’s remarkable engineering where specialized cells, dubbed iridophores, produce an efficient light reflector made of guanine-based crystals. This unique structure of the fish iris serves a dual function: In addition to its role as a light barrier, the iris has a second role of camouflaging the eye by creating a silvery reflectance, which merges with the fish skin. The underlying mechanism that enables the aforementioned dual functionality of the fish iris as well as the structural morphogenesis of the guanine reflector during embryonic development, remained unclear. We show that complex optical response of the iris is facilitated by the establishment of a high-order organization of multilayered guanine-based crystal reflectors and pigments.

scholarly journals Role of Selective Autophagy in Spermatogenesis and Male Fertility

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2523
Author(s):  
Chunyu Lv ◽  
Xiaoli Wang ◽  
Ying Guo ◽  
Shuiqiao Yuan
Keyword(s):  
Male Infertility ◽  
Male Fertility ◽  
Genetic Regulation ◽  
Underlying Mechanism ◽  
Intracellular Pathogens ◽  
Selective Autophagy ◽  
Reproductive Processes ◽  
Infertile Patients ◽  
Shed Light

Autophagy is a “self-eating” process that engulfs cellular contents for their subsequent digestion in lysosomes to engage the metabolic need in response to starvation or environmental insults. According to the contents of degradation, autophagy can be divided into bulk autophagy (non-selective autophagy) and selective autophagy. Bulk autophagy degrades non-specific cytoplasmic materials in response to nutrient starvation while selective autophagy targets specific cargoes, such as damaged organelles, protein aggregates, and intracellular pathogens. Selective autophagy has been documented to relate to the reproductive processes, especially for the spermatogenesis, fertilization, and biosynthesis of testosterone. Although selective autophagy is vital in the field of reproduction, its role and the underlying mechanism have remained unclear. In this review, we focus on selective autophagy to discuss the recent advances in our understanding of the mechanism and role of selective autophagy on spermatogenesis and male fertility in mammals. Understanding the role of selective autophagy during spermatogenesis will promote the recognition of genetic regulation in male infertility, and shed light on therapies of infertile patients.

scholarly journals An Update on the Role of the Actin Cytoskeleton in Plasmodesmata: A Focus on Formins

2021 ◽  
Vol 12 ◽  
Author(s):  
Min Diao ◽  
Shanjin Huang
Keyword(s):  
Plant Growth ◽  
Actin Cytoskeleton ◽  
Growth And Development ◽  
Cell Communication ◽  
Underlying Mechanism ◽  
Review Article ◽  
Plant Growth And Development ◽  
Shed Light

Cell-to-cell communication in plants is mediated by plasmodesmata (PD) whose permeability is tightly regulated during plant growth and development. The actin cytoskeleton has been implicated in regulating the permeability of PD, but the underlying mechanism remains largely unknown. Recent characterization of PD-localized formin proteins has shed light on the role and mechanism of action of actin in regulating PD-mediated intercellular trafficking. In this mini-review article, we will describe the progress in this area.

scholarly journals The genetic interaction of REVOLUTA  and WRKY53  links plant development, senescence, and immune responses

2021 ◽  
Author(s):  
Justine Bresson ◽  
Jasmin Doll ◽  
Francois Vasseur ◽  
Mark Stahl ◽  
Edda von Roepenack-Lahaye ◽  
...  
Keyword(s):  
Plant Development ◽  
Metabolic Pathways ◽  
Developmental Stages ◽  
Genetic Interaction ◽  
Plant Immunity ◽  
Annual Plants ◽  
Leaf Patterning ◽  
Developmental Phases ◽  
Early Developmental

In annual plants, tight coordination of successive developmental events is of primary importance to optimize performance under fluctuating environmental conditions. The recent finding of the genetic interaction of WRKY53 , a key senescence-related gene with REVOLUTA , a master regulator of early leaf patterning, raises the question of how early and late developmental events are connected. Here, we investigated the developmental and metabolic consequences of an alteration of the REVOLUTA  and WRKY53 gene expression, from seedling to fruiting . Our results show that REVOLUTA critically controls late developmental phases and reproduction while inversely WRKY53 determines vegetative growth at early developmental stages. We further show that these regulators of distinct developmental phases frequently, but not continuously, interact throughout ontogeny and demonstrated that their genetic interaction is mediated by the salicylic acid (SA). Moreover, we showed that REVOLUTA  and WRKY53  are keys regulatory nodes of development and plant immunity thought their role in SA metabolic pathways, which also highlights the role of REV in pathogen defence. Together, our findings demonstrate how late and early developmental events are tightly intertwined by molecular hubs. These hubs interact with each other throughout ontogeny, and participate to the interplay between plant development and immunity.

Tree fern indusia: studies of development and diversity

1975 ◽  
Vol 53 (20) ◽  
pp. 2260-2273 ◽  
Author(s):  
A. F. Tryon ◽  
L. J. Feldman
Keyword(s):  
Developmental Stages ◽  
Leaf Surface ◽  
Primary Role ◽  
Tree Fern ◽  
New Information ◽  
Ultimate Segment ◽  
Abaxial Leaf Surface ◽  
Early Developmental

Early developmental stages of the sorus in Cyathea fulva show that the indusium is initiated from cells of the protoderm on the abaxial leaf surface, closer to the midvein than the margin of the ultimate segment. This contrasts with earlier work on Alsophila tricolor that reported a marginal origin of the indusium and possible phyletic relations with the marginal sorus in the Dicksoniaceae. This new information is considered in an assessment of the numerous forms of the indusia in five genera of the Cyatheaceae. A series of photographs shows the principal forms and the diversity of sori and indusia in Sphaeropteris, Alsophila, Nephelea, Cyathea, and Cnemidaria, including species of both the paleotropics and neotropics. The figures illustrate the inadequacy of the earlier system of classification of these plants in three main genera based upon the type of indusium. The primary role of the indusium is considered to be the retardation of water loss during sporangial development and sporogenesis.

Development of pigment-cup eyes in the polychaetePlatynereis dumeriliiand evolutionary conservation of larval eyes in Bilateria

Development ◽  
2002 ◽  
Vol 129 (5) ◽  
pp. 1143-1154 ◽  
Author(s):  
Detlev Arendt ◽  
Kristin Tessmar ◽  
Maria-Ines Medeiros de Campos-Baptista ◽  
Adriaan Dorresteijn ◽  
Joachim Wittbrodt
Keyword(s):  
Visual System ◽  
Early Development ◽  
Developmental Stages ◽  
Photoreceptor Cells ◽  
Evolutionary Conservation ◽  
Early Developmental Stages ◽  
Platynereis Dumerilii ◽  
Differentiation Marker ◽  
Early Developmental

The role of Pax6 in eye development in insects and vertebrates supports the view that their eyes evolved from simple pigment-cup ocelli present in their last common ancestors (Urbilateria). The cerebral eyes in errant polychaetes represent prototype invertebrate pigment-cup ocelli and thus resemble the presumed ancestral eyes. We have analysed expression of conserved eye specification genes in the early development of larval and adult pigment-cup eyes in Platynereis dumerilii (Polychaeta, Annelida, Lophotrochozoa). Both larval and adult eyes form in close vicinity of the optic anlagen on both sides of the developing brain ganglia. While pax6 is expressed in the larval, but not in the developing, adult eyes, expression of six1/2 from trochophora stages onwards specifically outlines the optic anlagen and thus covers both the developing larval and adult eyes. Using Platynereis rhabdomeric opsin as differentiation marker, we show that the first pair of adult eye photoreceptor cells is detected within bilateral clusters that transitorily express ath, the Platynereis atonal orthologue, thus resembling proneural sensory clusters. Our data indicate that – similar to insects, but different from the vertebrates – polychaete six1/2 expression outlines the entire visual system from early developmental stages onwards and ath-positive clusters generate the first photoreceptor cells to appear. We propose that pax6-, six1/2- and ath-positive larval eyes, as found in today’s trochophora, were present already in Urbilateria.

Ocellar pigmentation and phototaxis in the nematode Mermis nigrescens: changes during development

2000 ◽  
Vol 203 (8) ◽  
pp. 1341-1350
Author(s):  
A.H. Burr ◽  
D. Wagar ◽  
P. Sidhu
Keyword(s):  
Previous Investigation ◽  
Developmental Stages ◽  
Life Stage ◽  
Positive Phototaxis ◽  
Mature Adults ◽  
Adult Females ◽  
Three Stages ◽  
Early Developmental ◽  
Scanning Motion

After 1 or 2 years of dormancy in the soil, Mermis nigrescens females emerge to lay eggs on vegetation where their grasshopper hosts are likely to feed. Females collected at this life stage exhibit a strong positive phototaxis and have a tubular region of pigmentation near the anterior tip consisting of concentrated oxyhaemoglobin. A previous investigation of the scanning motion of the ‘head’ and orientation of the ‘neck’ has implicated the shadowing of a photoreceptor inside the tube as the mechanism for identifying the direction of light during phototaxis. Here, we describe the development of the pigment in young adult females and investigate phototaxis in early developmental stages that lack the pigment. The orientation of the neck to a horizontal 420 nm stimulus (intensity 10(13)photons s(−)(1)cm(−)(2)) was measured for unpigmented fourth-stage larvae and immature adult females as well as mature females with pigmented ocelli. The orientation of the larvae and immature adults was weakly negative, whereas that of the mature adults was strongly positive. Head and neck movements were otherwise the same in the three stages. Thus, the pigmentation appears to be required for positive phototaxis, and the results provide further support for the shadowing role of ocellar haemoglobin.

scholarly journals Dual function of the PI3K-Akt-mTORC1 axis in myelination of the peripheral nervous system

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Gianluca Figlia ◽  
Camilla Norrmén ◽  
Jorge A Pereira ◽  
Daniel Gerber ◽  
Ueli Suter
Keyword(s):  
Nervous System ◽  
Schwann Cells ◽  
Developmental Stages ◽  
Dual Function ◽  
Control Mechanisms ◽  
Delayed Onset ◽  
Mtorc1 Signaling ◽  
Early Developmental Stages ◽  
Inhibitory Components ◽  
Early Developmental

Myelination is a biosynthetically demanding process in which mTORC1, the gatekeeper of anabolism, occupies a privileged regulatory position. We have shown previously that loss of mTORC1 function in Schwann cells (SCs) hampers myelination. Here, we genetically disrupted key inhibitory components upstream of mTORC1, TSC1 or PTEN, in mouse SC development, adult homeostasis, and nerve injury. Surprisingly, the resulting mTORC1 hyperactivity led to markedly delayed onset of both developmental myelination and remyelination after injury. However, if mTORC1 was hyperactivated after myelination onset, radial hypermyelination was observed. At early developmental stages, physiologically high PI3K-Akt-mTORC1 signaling suppresses expression of Krox20 (Egr2), the master regulator of PNS myelination. This effect is mediated by S6K and contributes to control mechanisms that keep SCs in a not-fully differentiated state to ensure proper timing of myelination initiation. An ensuing decline in mTORC1 activity is crucial to allow myelination to start, while remaining mTORC1 activity drives myelin growth.

Liriodenine, Early Antimicrobial Defence in Annona diversifolia

2011 ◽  
Vol 66 (7-8) ◽  
pp. 377-384 ◽  
Author(s):  
Iván De la Cruz-Chacón ◽  
Alma Rosa González-Esquinca ◽  
Patricia Guevara Fefer ◽  
Luis Felipe Jímenez Garcia
Keyword(s):  
High Performance ◽  
Positive Relationship ◽  
Developmental Stages ◽  
Rhizopus Stolonifer ◽  
Seed Deterioration ◽  
Aspergillus Glaucus ◽  
Early Developmental Stages ◽  
Alkaloid Extracts ◽  
Early Developmental

Annonaceae aporphine alkaloids, of which liriodenine is the most abundant, have not been extensively studied from a biological standpoint. The goal of this study was to investigate the role of liriodenine in antimicrobial defense during early developmental stages in Annona diversifolia. The fungi Rhizopus stolonifer and Aspergillus glaucus, which are responsible for seed deterioration, were isolated during imbibition, and their antifungal activity was determined by diffusion, macrodilution, and metabolic inhibition assays using purified liriodenine and alkaloid extracts obtained from embryos, radicles, and roots at early developmental stages. The presence of liriodenine in extracts was quantified by high-performance liquid chromatography. Purified liriodenine and alkaloidal extracts inhibited both fungi, and there was a positive relationship between extract activity and amount of liriodenine contained therein. The quantity of liriodenine present in extracts suggests its importance in controlling other phytopathogens.

scholarly journals Functional network antagonism through the prism of theories of consciousness

2021 ◽  
Author(s):  
Athena Demertzi ◽  
Aaron Kucyi ◽  
Georgios A. Keliris ◽  
Susan Whitfield-Gabrieli
Keyword(s):  
Developmental Stages ◽  
Underlying Mechanism ◽  
States Of Consciousness ◽  
Neural Inhibition ◽  
Early Developmental Stages ◽  
Comprehensive Manner ◽  
Cortical Regions ◽  
Early Developmental ◽  
The Brain ◽  
Integrated Information Theory

The brainʼs spontaneous activity changes across states of consciousness. A particular consciousness-mediated brain configuration is the antagonistic relationship between the default mode network (encompassing mainly midline cortical regions) and frontoparietal areas (DMN anticorrelations). Functional anticorrelations especially have been shown to be important for behavior and consciousness, as they are absent or substantially reduced in early developmental stages, states of anesthesia, and disorders of consciousness. To date, though, theories of consciousness do not frame the anticorrelations in a comprehensive manner. Here, by tackling their biological origins, we suggest that neural inhibition is the underlying mechanism which mediates the emerging architecture of the fMRI anticorrelations. We go on to propose that neural inhibition reflects the process of functional segregation, namely the capacity of the brain to show selectivity in the areas which will be functionally connected. We then see how this view of segregation is met in the Global Neuronal Workspace Theory (GNWT, inhibition) and the Integrated Information Theory (IIT, differentiation) and propose that the anticorrelations can be considered as the quantifiable counterpart of these theoretical notions. We believe that this stance on functional anticorrelations will shed more light on what inter-network antagonism means for consciousness, and will open discussions about pragmatic quantifications of theoretical notions within consciousness research.

scholarly journals Oligodendrocytes Development and Wnt Signaling Pathway

2018 ◽  
Vol 1 (3) ◽  
pp. 17-35 ◽  
Author(s):  
Shahid Hussain Soomro ◽  
Jifu Jie ◽  
Hui Fu
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Developmental Stages ◽  
Critical Role ◽  
Wnt Signaling Pathway ◽  
Study Groups ◽  
Multiple Roles ◽  
Proliferation And Differentiation ◽  
Early Developmental

Oligodendrocytes are specialized glial cell in central nervous system (CNS) responsible for the formation of myelin sheath around the axon. Oligodendrocyte proliferation and differentiation is regulated by Wnt signaling pathway, at various stages. However, different study groups have described controversial conclusions about the effect of Wnt on oligodendrocytes precursor cells (OPCs) development. Initially it has been proposed that Wnt pathway negatively regulates the OPCs proliferation and differentiation but recently some studies have described that Wnt promotes the differentiation of OPCs. After carefully reviewing the literature, we believe that Wnt play multiple roles in OPCs differentiation and its function is time (stage) and dose sensitive. Low to moderate activation of Wnt promotes OPC development, while too much or too low is inhibitory. Current evidences also suggested that in early developmental stages, Wnt inhibits the OPCs formation from neural progenitors and differentiation into immature oligodendrocytes. But in late stages Wnt plays promoting role in differentiation and maturation of oligodendrocytes. This review summarized the updated information regarding the critical role of Wnt signaling cascade in proliferation and differentiation of OPCs.

Sign in / Sign up

Export Citation Format

Share Document