scholarly journals LARVAL STRATEGY OF TWO SPECIES OF SEED-FEEDING CHALCIDOIDEA PARALLELS THAT OF PARASITOID KOINOBIONTS

2020 ◽  
Vol 24 (04) ◽  
pp. 903-916
Author(s):  
Sergio Jansen-González ◽  
◽  
Simone Pádua Teixeira ◽  
Rodrigo Augusto Santinelo Pereira ◽  
Keyword(s):  
Larval Instar ◽  
Time Windows ◽  
Structural Complexity ◽  
Plant Interactions ◽  
Future Studies ◽  
Seed Predators ◽  
Immature Seeds ◽  
Annona Crassiflora ◽  
Plant Embryo ◽  
Progressive Accumulation

The association between ontogenetic processes in plants and phytophagous insects is not traditionally considered in studies of insect-plant interactions. Angiosperm seeds impose important constraints on seed predators; the structural complexity of seeds and the progressive accumulation of resources throughout their development limit the time windows when resources can be retrieved by the predator. Some holometabolous insects deposit their eggs inside immature seeds, with the immature stages of both insect and plant cohabiting in a space with limited but potential resources. We studied the larval development of Megastigmus transvaalensis (Hussey, 1956) (Chalcidoidea: Megastigmidae) and Bephratelloides pomorum (F., 1804) (Chalcidoidea: Eurytomidae) and the seed development of their respective hosts, Schinus terebinthifolia (Raddi, 1820) (Anacardiaceae) and Annona crassiflora (Mart., 1841) (Annonaceae). Our results show that both M. transvaalensis and B. pomorum oviposit in immature fruits, whose protective tissues surrounding the seeds are softer. The first larval instar interferes little with the development of the seed, allowing both seed and plant embryo to continue growing. When the infested seed reaches the size of a mature, non-infested seed, the larva grows rapidly and consumes most of it. M. transvaalensis induces minor modifications in the endosperm cells, while B. pomorum does not induce any visual modifications. The strategy of allowing seed/plant embryo to continue growing shows similarities to the endoparasitic koinobiont strategy followed by some chalcid parasitoids, which keep their host alive while feeding upon it. Future studies should be expanded to other chalcid seed predators in order to understand the evolution of convergent patterns among seed-feeding insects and its evolution in relation to parasitoid strategies inside the group

Complex Ant-Plant Interactions: Rain-Forest Ants as Secondary Dispersers and Post-Dispersal Seed Predators

Ecology ◽  
1993 ◽  
Vol 74 (6) ◽  
pp. 1802-1812 ◽  
Author(s):  
Douglas J. Levey ◽  
Margaret M. Byrne
Keyword(s):  
Rain Forest ◽  
Plant Interactions ◽  
Seed Predators

scholarly journals A revised classification of the sister tribes Palicoureeae and Psychotrieae (Rubiaceae) indicates genus-specific alkaloid accumulation

2021 ◽  
Author(s):  
Andreas Berger ◽  
Karin Valant-Vetschera ◽  
Johann Schinnerl ◽  
Lothar Brecker
Keyword(s):  
Secondary Metabolites ◽  
Indole Alkaloid ◽  
Plant Interactions ◽  
Future Studies ◽  
Important Group ◽  
Pharmacological Significance ◽  
The Common ◽  
Phytochemical Studies ◽  
Common Perception

AbstractTribes Palicoureeae and Psychotrieae (Rubiaceae, Gentianales) are complex and speciose sister groups with a pantropical distribution. Since the initial studies on ipecacuanha more than two centuries ago, species of the group have been subject to numerous phytochemical studies yielding diverse specialized ("secondary") metabolites, most of them alkaloids. However, the generic limits within the tribes have long been unclear and only recently, monophyletic genera have been delimited and segregated from a once broadly circumscribed Psychotria. Thus, a phylogeny-based and taxonomically updated review of phytochemical literature was performed which allowed assigning the bulk of phytochemical data previously reported for Psychotria to various segregate genera such as Carapichea, Eumachia and Palicourea. This review not only challenges the common perception of Psychotria as a monoterpene-indole alkaloid-rich genus. It also highlights that each of its relatives differs by accumulating specific groups of alkaloids, which is of major importance for understanding animal-plant interactions such as herbivory, as well as for drug discovery. The alkaloid complement of each of these genera is here enumerated and discussed, which should provide a framework for future studies addressing the biosynthesis, evolution, ecological and pharmacological significance of specialized metabolite differentiation in this abundant, ecologically and ethnopharmacologically important group.

scholarly journals Fish Corral Composition, Abundance, and Distribution in the Reef Flat of Palompon, Leyte, Philippines

2011 ◽  
pp. 62-84
Author(s):  
Jerome Benedict Cabansag ◽  
Arriane Krisna Rose Tuazon ◽  
Liezel Paraboles
Keyword(s):  
Reef Flat ◽  
Structural Complexity ◽  
Total Catch ◽  
Future Studies ◽  
Spatial Trends ◽  
Fish Catch ◽  
Temporal And Spatial ◽  
Catch Composition ◽  
Abundance And Distribution ◽  
Distribution Of Fish

There is paucity of studies relating to fish corral fishery and its management particularly those operated on reef flats. This study was conducted to evaluate the fish catch composition of fish corrals situated in the reef flat of Palompon, Leyte from July 2009 to January 2010. During the monitoring, two sets of data were utilized: the semimonthly field intercept samplings and the daily fish landing data. Field intercept samplings enabled the researchers to approach fishers as they were gathering their fish catch that was eventually identified, sorted, measured, and weighed. Fish landing data recorded by local enumerators included the fish’s local name and corresponding weight. From 27 fish corrals, the intercept samplings yielded a total catch of 23.9 kg, which was composed of 81 identified species under 47 genera from 31 families. The most abundant family was Siganidae comprising 44% of the total catch, followed by Apogonidae (18%) and Pomacentridae (9%). This composition was corroborated by the fish landed data. The temporal and spatial trends of the catch composition showed that Fam. Siganidae was most abundant in the months of July, October, and December, while Apogonidae in the months of August and November. It was observed that there was an unequal spatial distribution of fish species in the study area. Of the four sampling areas, Area 2 on the northeastern part of Palompon was the most diverse due partly to the high number of fish corral units and the area’s structural complexity wherein seagrass and algal beds were most extensive interspersed with coral patches. Results of this study could serve as reference for future studies dealing with monitoring and managing fish corral fishery.

scholarly journals A new hypothesis for the importance of seed dispersal in time

2018 ◽  
pp. 1795-1803
Author(s):  
Adriana Guzmán ◽  
Pablo R. Stevenson
Keyword(s):  
Seed Dispersal ◽  
Plant Species ◽  
Seed Predation ◽  
Survival Rates ◽  
Species Dispersal ◽  
Future Studies ◽  
Seed Predators ◽  
Colombian Amazon ◽  
New Hypothesis ◽  
Escape Hypothesis

Most studies on seed dispersal in time have focused on seed dormancy and the physiological triggers for germination. However, seed dispersed by animals with low metabolic and moving rates, and long gutpassage times such as terrestrial turtles, could be considered another type of dispersal in time. This study tests the hypothesis that seeds dispersed in time may lower predation rates. We predicted that seeds deposited below parent trees after fruiting fall has finished is advantageous to minimize seed predators and should show higher survival rates. Four Amazonian plant species, Dicranostyles ampla, Oenocarpus bataua, Guatteria atabapensis and Ocotea floribunda, were tested for seed survival probabilities in two periods: during fruiting and 10-21 days after fruiting. Experiments were carried out in two biological stations located in the Colombian Amazon (Caparú and Zafire Biological Stations). Seed predation was high and mainly caused by non-vertebrates. Out of the four plant species tested, only Guatteria atabapensis supported the time escape hypothesis. For this species, seed predation by vertebrates after the fruiting period increased (from 4.1% to 9.2%) while seed predation by nonvertebrates decreased (from 54.0% to 40.2%). in contrast, seed predation by vertebrates and by non-vertebrates after the fruiting period in D. ampla increased (from 7.9% to 22.8% and from 40.4% to 50.6%, respectively), suggesting predator satiation. Results suggest that for some species dispersal in time could be advantageous to avoid some type of seed predators. Escape in time could be an additional dimension in which seeds may reach adequate sites for recruitment. Thus, future studies should be address to better understand the survival advantages given by an endozoochory time-dispersal process.

scholarly journals Thermal summation model and instar determination of all developmental stages of necrophagous beetle,Sciodrepoides watsoni(Spence) (Coleoptera: Leiodidae: Cholevinae)

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1944 ◽  
Author(s):  
Pavel Jakubec
Keyword(s):  
Forensic Entomology ◽  
Developmental Stages ◽  
Larval Instar ◽  
Head Capsule ◽  
Common Species ◽  
Standard Errors ◽  
Future Studies ◽  
Post Mortem Interval ◽  
Holarctic Region

Necrophagous beetles are underrepresented in forensic entomology studies despite their undeniable utility for the field. In the present article, information is presented regarding the developmental biology and instar determination ofSciodrepoides watsoni(Spence, 1813), a very common species occurring across the Holarctic region. Wild collected beetles were kept in climate chambers at constant temperature (12, 15, 18, 21 and 28 °C) and their development was regularly documented. Parameters of thermal summation models and standard errors were calculated for each developmental stage. These models may be used for an estimation of post-mortem interval in legal investigations after further validation on local populations ofS. watsoni. An additional methodology is introduced for future studies of size-based characteristics, addressing instar identification bias. The methodology provided estimations (mean, standard error and standard deviation) ofS. watsonilarval head capsule width for preliminary larval instar determination. The methodology may be used with other morphological features to improve instar determination accuracy.

Conformation of eukaryotic ribosomal RNAs

1983 ◽  
Vol 41 ◽  
pp. 592-593
Author(s):  
M. Boublik ◽  
G. Thornton ◽  
G. Oostergetel ◽  
J.F. Hainfeld ◽  
J.S. Wall
Keyword(s):  
Molecular Weight ◽  
Mass Measurement ◽  
Carbon Film ◽  
Structural Complexity ◽  
Scanning Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Pure Nitrogen ◽  
Freeze Dried ◽  
Scanning Transmission ◽  
Partially Unfolded

Understanding the structural complexity of ribosomes and their role in protein synthesis requires knowledge of the conformation of their components - rRNAs and proteins. Application of dedicated scanning transmission electron microscope (STEM), electrical discharge of the support carbon film in an atmosphere of pure nitrogen, and determination of the molecular weight of individual rRNAs enabled us to obtain high resolution electron microscopic images of unstained freeze-dried rRNA molecules from BHK cells in a form suitable for evaluation of their 3-D structure. Preliminary values for the molecular weight of 28S RNA from the large and 18S RNA from the small ribosomal subunits as obtained by mass measurement were 1.84 x 106 and 0.97 x 106, respectively. Conformation of rRNAs consists, in general, of alternating segments of intramolecular hairpin stems and single stranded loops in a proportion which depends on their ionic environment, the Mg++ concentration in particular. Molecules of 28S RNA (Fig. 1) and 18S RNA (not shown) obtained by freeze-drying from a solution of 60 mM NH+4 acetate and 2 mM Mg++ acetate, pH 7, appear as partially unfolded coils with compact cores suggesting a high degree of ordered secondary structure.

An Early Developmental Marker for Radial Glia in Rat Spinal Cord

1996 ◽  
Vol 54 ◽  
pp. 36-37
Author(s):  
V. Kriho ◽  
H.-Y. Yang ◽  
C.-M. Lue ◽  
N. Lieska ◽  
G. D. Pappas
Keyword(s):  
Spinal Cord ◽  
Intermediate Filament ◽  
Radial Glia ◽  
Rat Spinal Cord ◽  
Future Studies ◽  
Spinal Cord Development ◽  
Median Septum ◽  
Differentiation Marker ◽  
Early Developmental ◽  
Developing Rat

Radial glia have been classically defined as those early glial cells that radially span their thin processes from the ventricular to the pial surfaces in the developing central nervous system. These radial glia constitute a transient cell population, disappearing, for the most part, by the end of the period of neuronal migration. Traditionally, it has been difficult to definitively identify these cells because the principal criteria available were morphologic only.Using immunofluorescence microscopy, we have previously defined a phenotype for radial glia in rat spinal cord based upon the sequential expression of vimentin, glial fibrillary acidic protein and an intermediate filament-associated protein, IFAP-70/280kD. We report here the application of another intermediate filament-associated protein, IFAP-300kD, originally identified in BHK-21 cells, to the immunofluorescence study of radial glia in the developing rat spinal cord.Results showed that IFAP-300kD appeared very early in rat spinal cord development. In fact by embryonic day 13, IFAP-300kD immunoreactivity was already at its peak and was observed in most of the radial glia which span the spinal cord from the ventricular to the subpial surfaces (Fig. 1). Interestingly, from this time, IFAP-300kD immunoreactivity diminished rapidly in a dorsal to ventral manner, so that by embryonic day 16 it was detectable only in the maturing macroglial cells in the marginal zone of the spinal cord and the dorsal median septum (Fig. 2). By birth, the spinal cord was essentially immuno-negative for this IFAP. Thus, IFAP-300kD appears to be another differentiation marker available for future studies of gliogenesis, especially for the early stages of radial glia differentiation.

Observations of Frozen-Hydrated Microtubules

1990 ◽  
Vol 48 (1) ◽  
pp. 504-505
Author(s):  
D. Chrétien ◽  
D. Job ◽  
R.H. Wade
Keyword(s):  
Fourier Transforms ◽  
Structural Complexity ◽  
Image Contrast ◽  
Phase Behaviour ◽  
Experimental Conditions ◽  
Thin Sections ◽  
Surface Lattice ◽  
Cilia And Flagella ◽  
Outstanding Question

Microtubules are filamentary structures found in the cytoplasm of eukaryotic cells, where, together with actin and intermediate filaments, they form the components of the cytoskeleton. They have many functions and show various levels of structural complexity as witnessed by the singlet, doublet and triplet structures involved in the architecture of centrioles, basal bodies, cilia and flagella. The accepted microtubule model consists of a 25 nm diameter hollow tube with a wall made up of 13 paraxial protofilaments (pf). Each pf is a string of aligned tubulin dimers. Some results have suggested that the pfs follow a superhelix. To understand how microtubules function in the cell an accurate model of the surface lattice is one of the requirements. For example the 9x2 architecture of the axoneme will depend on the organisation of its component microtubules. We should also note that microtubules with different numbers of pfs have been observed in thin sections of cellular and of in-vitro material. An outstanding question is how does the surface lattice adjust to these different pf numbers?We have been using cryo-electron microscopy of frozen-hydrated samples to study in-vitro assembled microtubules. The experimental conditions are described in detail in this reference. The results obtained in conjunction with thin sections of similar specimens and with axoneme outer doublet fragments have already allowed us to characterise the image contrast of 13, 14 and 15 pf microtubules on the basis of the measured image widths, of the the image contrast symmetry and of the amplitude and phase behaviour along the equator in the computed Fourier transforms. The contrast variations along individual microtubule images can be interpreted in terms of the geometry of the microtubule surface lattice. We can extend these results and make some reasonable predictions about the probable surface lattices in the case of other pf numbers, see Table 1. Figure 1 shows observed images with which these predictions can be compared.

Autophagy and ageing: implications for age-related neurodegenerative diseases

2013 ◽  
Vol 55 ◽  
pp. 119-131 ◽  
Author(s):  
Bernadette Carroll ◽  
Graeme Hewitt ◽  
Viktor I. Korolchuk
Keyword(s):  
Neurodegenerative Diseases ◽  
Energy Availability ◽  
Future Studies ◽  
Intracellular Degradation ◽  
Age Related ◽  
Autophagy Induction ◽  
Social Importance ◽  
Cellular Dysfunction ◽  
Autophagy Activity ◽  
Intense Research

Autophagy is a process of lysosome-dependent intracellular degradation that participates in the liberation of resources including amino acids and energy to maintain homoeostasis. Autophagy is particularly important in stress conditions such as nutrient starvation and any perturbation in the ability of the cell to activate or regulate autophagy can lead to cellular dysfunction and disease. An area of intense research interest is the role and indeed the fate of autophagy during cellular and organismal ageing. Age-related disorders are associated with increased cellular stress and assault including DNA damage, reduced energy availability, protein aggregation and accumulation of damaged organelles. A reduction in autophagy activity has been observed in a number of ageing models and its up-regulation via pharmacological and genetic methods can alleviate age-related pathologies. In particular, autophagy induction can enhance clearance of toxic intracellular waste associated with neurodegenerative diseases and has been comprehensively demonstrated to improve lifespan in yeast, worms, flies, rodents and primates. The situation, however, has been complicated by the identification that autophagy up-regulation can also occur during ageing. Indeed, in certain situations, reduced autophagosome induction may actually provide benefits to ageing cells. Future studies will undoubtedly improve our understanding of exactly how the multiple signals that are integrated to control appropriate autophagy activity change during ageing, what affect this has on autophagy and to what extent autophagy contributes to age-associated pathologies. Identification of mechanisms that influence a healthy lifespan is of economic, medical and social importance in our ‘ageing’ world.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

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