Sperm chemotaxis is driven by the slope of the chemoattractant concentration field

Mapping Intimacies ◽

10.1101/148650 ◽

2017 ◽

Author(s):

H.V. Ramírez-Gómez ◽

V. Jimenez Sabinina ◽

M. Velázquez-Pérez ◽

C. Beltrán ◽

J. Carneiro ◽

...

Keyword(s):

Marine Invertebrates ◽

Concentration Field ◽

Stimulus Function ◽

Frequency Entrainment ◽

Sperm Chemotaxis ◽

Coupling Force ◽

Intracellular Ca ◽

Species Specific ◽

First Time ◽

Fundamental Requirement

AbstractSpermatozoa of marine invertebrates are attracted to their conspecific female gamete by diffusive molecules, called chemoattractants, released from the egg investments in a process known as chemotaxis. The information from the egg chemoattractant concentration field is decoded into intracellular Ca2+ concentration ([Ca2+]i) changes that regulate the internal motors that shape the flagellum as it beats. By studying sea urchin species-specific differences in sperm chemoattractant-receptor characteristics we show that receptor density constrains the steepness of the chemoattractant concentration gradient detectable by spermatozoa. Through analyzing different chemoattractant gradient forms, we demonstrate for the first time that Strongylocentrotus purpuratus sperm are chemotactic and this response is consistent with frequency entrainment of two coupled physiological oscillators: i) the stimulus function and ii) the [Ca2+]i changes. We demonstrate that the slope of the chemoattractant gradients provides the coupling force between both oscillators, arising as a fundamental requirement for sperm chemotaxis.

Sperm chemotaxis is driven by the slope of the chemoattractant concentration field

eLife ◽

10.7554/elife.50532 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 1

Author(s):

Héctor Vicente Ramírez-Gómez ◽

Vilma Jimenez Sabinina ◽

Martín Velázquez Pérez ◽

Carmen Beltran ◽

Jorge Carneiro ◽

...

Keyword(s):

Marine Invertebrates ◽

Strongylocentrotus Purpuratus ◽

Concentration Field ◽

Stimulus Function ◽

Frequency Entrainment ◽

Sperm Chemotaxis ◽

Coupling Force ◽

Species Specific ◽

First Time ◽

Fundamental Requirement

Spermatozoa of marine invertebrates are attracted to their conspecific female gamete by diffusive molecules, called chemoattractants, released from the egg investments in a process known as chemotaxis. The information from the egg chemoattractant concentration field is decoded into intracellular Ca2+ concentration ([Ca2+]i) changes that regulate the internal motors that shape the flagellum as it beats. By studying sea urchin species-specific differences in sperm chemoattractant-receptor characteristics we show that receptor density constrains the steepness of the chemoattractant concentration gradient detectable by spermatozoa. Through analyzing different chemoattractant gradient forms, we demonstrate for the first time that Strongylocentrotus purpuratus sperm are chemotactic and this response is consistent with frequency entrainment of two coupled physiological oscillators: i) the stimulus function and ii) the [Ca2+]i changes. We demonstrate that the slope of the chemoattractant gradients provides the coupling force between both oscillators, arising as a fundamental requirement for sperm chemotaxis.

Bark traits, decomposition and flammability of Australian forest trees

Australian Journal of Botany ◽

10.1071/bt16258 ◽

2017 ◽

Vol 65 (4) ◽

pp. 327 ◽

Cited By ~ 4

Author(s):

Saskia Grootemaat ◽

Ian J. Wright ◽

Peter M. van Bodegom ◽

Johannes H. C. Cornelissen ◽

Veronica Shaw

Keyword(s):

Forest Tree ◽

Remarkable Feature ◽

Interspecific Differences ◽

Eucalypt Plantations ◽

Physical Traits ◽

Key Driver ◽

Multiple Species ◽

Species Specific ◽

First Time ◽

Different Tissues

Bark shedding is a remarkable feature of Australian trees, yet relatively little is known about interspecific differences in bark decomposability and flammability, or what chemical or physical traits drive variation in these properties. We measured the decomposition rate and flammability (ignitibility, sustainability and combustibility) of bark from 10 common forest tree species, and quantified correlations with potentially important traits. We compared our findings to those for leaf litter, asking whether the same traits drive flammability and decomposition in different tissues, and whether process rates are correlated across tissue types. Considerable variation in bark decomposability and flammability was found both within and across species. Bark decomposed more slowly than leaves, but in both tissues lignin concentration was a key driver. Bark took longer to ignite than leaves, and had longer mass-specific flame durations. Variation in flammability parameters was driven by different traits in the different tissues. Decomposability and flammability were each unrelated, when comparing between the different tissue types. For example, species with fast-decomposing leaves did not necessarily have fast-decomposing bark. For the first time, we show how patterns of variation in decomposability and flammability of bark diverge across multiple species. By taking species-specific bark traits into consideration there is potential to make better estimates of wildfire risks and carbon loss dynamics. This can lead to better informed management decisions for Australian forests, and eucalypt plantations, worldwide.

The Morphological and Anatomical Traits of the Leaf in Representative Vinca Species Observed on Indoor- and Outdoor-Grown Plants

Plants ◽

10.3390/plants10040622 ◽

2021 ◽

Vol 10 (4) ◽

pp. 622

Author(s):

Alexandra Ciorîță ◽

Septimiu Cassian Tripon ◽

Ioan Gabriel Mircea ◽

Dorina Podar ◽

Lucian Barbu-Tudoran ◽

...

Keyword(s):

Spongy Parenchyma ◽

Palisade And Spongy Parenchyma ◽

Chemical Composition Of Plants ◽

Ultrastructural Characteristics ◽

Species Specific ◽

Microscopy Techniques ◽

First Time ◽

Thick Layers ◽

Space Ratio ◽

Indoor And Outdoor

Morphological and anatomical traits of the Vinca leaf were examined using microscopy techniques. Outdoor Vinca minor and V. herbacea plants and greenhouse cultivated V. major and V. major var. variegata plants had interspecific variations. All Vinca species leaves are hypostomatic. However, except for V. minor leaf, few stomata were also present on the upper epidermis. V. minor leaf had the highest stomatal index and V. major had the lowest, while the distribution of trichomes on the upper epidermis was species-specific. Differentiated palisade and spongy parenchyma tissues were present in all Vinca species’ leaves. However, V. minor and V. herbacea leaves had a more organized anatomical aspect, compared to V. major and V. major var. variegata leaves. Additionally, as a novelty, the cellular to intercellular space ratio of the Vinca leaf’s mesophyll was revealed herein with the help of computational analysis. Lipid droplets of different sizes and aspects were localized in the spongy parenchyma cells. Ultrastructural characteristics of the cuticle and its epicuticular waxes were described for the first time. Moreover, thick layers of cutin seemed to be characteristic of the outdoor plants only. This could be an adaptation to the unpredictable environmental conditions, but nevertheless, it might influence the chemical composition of plants.

Bio-inspired design of ice-retardant devices based on benthic marine invertebrates: the effect of surface texture

10.1101/005470 ◽

2014 ◽

Author(s):

Homayun Mehrabani ◽

Neil Ray ◽

Kyle Tse ◽

Dennis Evangelista

Keyword(s):

Surface Texture ◽

Marine Invertebrates ◽

Freezing Point ◽

Three Dimensional ◽

Surface Pattern ◽

Ice Formation ◽

Cold Air ◽

Three Dimensional Printing ◽

Species Specific ◽

Effect Of Surface

Growth of ice on surfaces poses a challenge for both organisms and for devices that come into contact with liquids below the freezing point. Resistance of some organisms to ice formation and growth, either in subtidal environments (e.g. Antarctic anchor ice), or in environments with moisture and cold air (e.g.vplants, intertidal) begs examination of how this is accomplished. Several factors may be important in promoting or mitigating ice formation. As a start, here we examine the effect of surface texture alone. We tested four candidate surfaces, inspired by hard-shelled marine invertebrates and constructed using a three-dimensional printing process. We screened biological and artifical samples for ice formation and accretion in submerged conditions using previous methods, and developed a new test to examine ice formation from surface droplets as might be encountered in environments with moist, cold air. It appears surface texture plays only a small role in delaying the onset of ice formation: a stripe feature (corresponding to patterning found on valves of blue mussels,Crassostrea gigas, or on the spines of the Antarctic sea urchinSterechinus neumayeri) slowed ice formation an average of 25% compared to a grid feature (corresponding to patterning found on sub-polar butterclams,Saxidomas nuttali). The geometric dimensions of the features have only a small (~6%) effect on ice formation. Surface texture affects ice formation, but does not explain by itself the large variation in ice formation and species-specific ice resistance observed in other work. This suggests future examination of other factors, such as material elastic properties and coatings, and their interaction with surface pattern.

Ribosome profiling in Streptococcus pneumoniae reveals the role of methylation of 23S rRNA nucleotide G748 on ribosome stalling

10.1101/2020.12.21.423859 ◽

2020 ◽

Author(s):

Tatsuma Shoji ◽

Akiko Takaya ◽

Yoko Kusuya ◽

Hiroki Takahashi ◽

Hiroto Kawashima

Keyword(s):

Streptococcus Pneumoniae ◽

Ribosome Profiling ◽

23S Rrna ◽

Ribosome Stalling ◽

70S Ribosome ◽

Exit Tunnel ◽

Species Specific ◽

Peptidyltransferase Center ◽

First Time

2.Abstract(1) BackgroundMany nucleotides in 23S rRNA are methylated post-transcriptionally by methyltransferases and cluster around the peptidyltransferase center (PTC) and the nascent peptidyl exit tunnel (NPET) located in 50S subunit of 70S ribosome. Biochemical interactions between a nascent peptide and the tunnel may stall ribosome movement and affect expression levels of the protein. However, no studies have shown a role for NPET on ribosome stalling using an NPET mutant.(2) ResultsA ribosome profiling assay in Streptococcus pneumoniae demonstrates for the first time that an NPET mutant exhibits completely different ribosome occupancy compared to wild-type. We demonstrate, using RNA footprinting, that changes in ribosome occupancy correlate with changes in ribosome stalling. Further, statistical analysis shows that short peptide sequences that cause ribosome stalling are species-specific and evolutionarily selected. NPET structure is required to realize these specie-specific ribosome stalling.(3) ConclusionsResults support the role of NPET on ribosome stalling. NPET structure is required to realize the species-specific and evolutionary conserved ribosome stalling. These findings clarify the role of NPET structure on the translation process.

The “good, the bad and the double-sword” effects of exposure to MPs and their organic additives on N2-fixing bacteria

10.1101/2020.07.21.210740 ◽

2020 ◽

Author(s):

Víctor Fernández-Juárez ◽

Xabier López-Alforja ◽

Aida Frank-Comas ◽

Pedro Echeveste ◽

Antoni Bennasar-Figueras ◽

...

Keyword(s):

Posidonia Oceanica ◽

Dioctyl Phthalate ◽

Benthic Organisms ◽

Protein Overexpression ◽

Organic Additives ◽

Physical Interactions ◽

High Concentrations ◽

Species Specific ◽

Micro Organisms ◽

First Time

AbstractThe accumulation of microplastics (MPs) pollution at depths suggests the susceptibility of benthic organisms (e.g. seagrasses and their associated macro- and micro-organisms) to the effects of these pollutants. Little is known about the direct effects of MPs and their organic additives on marine bacteria, e.g. in one of the most ecologically significant groups, the diazotrophs or N2-fixing bacteria. To fill this gap of knowledge, we exposed marine diazotrophs found in association with the endemic Mediterranean seagrass Posidonia oceanica to pure MPs which differ in physical properties (e.g. density, hydrophobicity and/or size), namely, polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and polystyrene (PS) and to their most abundant associated organic additives (e.g. fluoranthene, 1,2,5,6,9,10-hexabromocyclododecane [HBCD] and dioctyl-phthalate [DEHP]). Growth, protein overexpression, direct physical interactions between MPs and bacteria, phosphorus (P) acquisition mechanisms and N2-fixation rates were evaluated. Our results show species-specific responses of the autotrophic and heterotrophic N2-fixing bacteria tested and the responses were dependent on the type and concentration of MPs and additives. N2-fixing cyanobacteria were positively affected by environmental and high concentrations of MPs (e.g. PVC), as opposed to heterotrophic strains, that were only positively affected with high concentrations of ∼120 µm-size MPs (detecting the overexpression of proteins related to plastic degradation and C-transport), and negatively affected by 1 µm-size PS beads. Generally, the organic additives (e.g. fluoranthene) had a deleterious effect in both autotrophic and heterotrophic N2-fixing bacteria and the magnitude of the effect is suggested to be dependent on bacterial size. We did not find evidences that specific N2-fixation rates were significantly affected by exposure to MPs, albeit changes in bacterial abundance can affect the bulk N2-fixation rates. In summary, we reported for the first time, the beneficial (the “good”), deleterious (the “bad”) and/or both (the “double-sword”) effects of exposure to MPs and their organic additives on diazotrophs found in association with seagrasses.

Species-specific difference in distribution of voltage-gated L-type Ca2+ channels of cardiac myocytes

AJP Cell Physiology ◽

10.1152/ajpcell.2000.279.6.c1963 ◽

2000 ◽

Vol 279 (6) ◽

pp. C1963-C1969 ◽

Cited By ~ 27

Author(s):

Yoshiko Takagishi ◽

Kenji Yasui ◽

Nicholas J. Severs ◽

Yoshiharu Murata

Keyword(s):

Electron Microscopy ◽

Plasma Membrane ◽

Cardiac Myocytes ◽

Immunogold Electron Microscopy ◽

Surface Plasma ◽

Gold Particles ◽

Intracellular Ca ◽

Rat Myocytes ◽

T Tubules ◽

Species Specific

Ca2+influx via sarcolemmal voltage-dependent Ca2+ channels (L-type Ca2+ channels) is the fundamental step in excitation-contraction (E-C) coupling in cardiac myocytes. Physiological and pharmacological studies reveal species-specific differences in E-C coupling resulting from a difference in the contribution of Ca2+ influx and intracellular Ca2+ release to activation of contraction. We investigated the distribution of L-type Ca2+ channels in isolated cardiac myocytes from rabbit and rat ventricle by correlative immunoconfocal and immunogold electron microscopy. Immunofluorescence labeling revealed discrete spots in the surface plasma membrane and transverse (T) tubules in rabbit myocytes. In rat myocytes, labeling appeared more intense in T tubules than in the surface sarcolemma. Immunogold electron microscopy extended these findings, showing that the number of gold particles in the surface plasma membrane was significantly higher in rabbit than rat myocytes. In rabbit myocyte plasma membrane, the gold particles were distributed as clusters in both regions that were associated with junctional sarcoplasmic reticulum and those that were not. The findings are consistent with the idea that influx of Ca2+ via surface sarcolemmal Ca2+ channels contributes to intracellular Ca2+ to a greater degree in rabbit than in rat myocytes.

Green Fluorescence Patterns in Closely Related Symbiotic Species of Zanclea (Hydrozoa, Capitata)

Diversity ◽

10.3390/d12020078 ◽

2020 ◽

Vol 12 (2) ◽

pp. 78 ◽

Cited By ~ 2

Author(s):

Davide Maggioni ◽

Luca Saponari ◽

Davide Seveso ◽

Paolo Galli ◽

Andrea Schiavo ◽

...

Keyword(s):

Cryptic Species ◽

Genetic Divergence ◽

Large Scale ◽

Marine Invertebrates ◽

Fluorescent Proteins ◽

Green Fluorescent Proteins ◽

Green Fluorescence ◽

Promising Tool ◽

Species Specific ◽

Green Fluorescent

Green fluorescence is a common phenomenon in marine invertebrates and is caused by green fluorescent proteins. Many hydrozoan species display fluorescence in their polyps and/or medusa stages, and in a few cases patterns of green fluorescence have been demonstrated to differ between closely related species. Hydrozoans are often characterized by the presence of cryptic species, due to the paucity of available morphological diagnostic characters. Zanclea species are not an exception, showing high genetic divergence compared to a uniform morphology. In this work, the presence of green fluorescence and the morpho-molecular diversity of six coral- and bryozoan-associated Zanclea species from the Maldivian coral reefs were investigated. Specifically, the presence of green fluorescence in polyps and newly released medusae was explored, the general morphology, as well as the cnidome and the interaction with the hosts, were characterized, and the 16S rRNA region was sequenced and analyzed. Overall, Zanclea species showed a similar morphology, with little differences in the general morphological features and in the cnidome. Three of the analyzed species did not show any fluorescence in both life stages. Three other Zanclea species, including two coral-associated cryptic species, were distinguished by species-specific fluorescence patterns in the medusae. Altogether, the results confirmed the morphological similarity despite high genetic divergence in Zanclea species and indicated that fluorescence patterns may be a promising tool in further discriminating closely related and cryptic species. Therefore, the assessment of fluorescence at a large scale in the whole Zancleidae family may be useful to shed light on the diversity of this enigmatic taxon.

Acidosis antagonizes intracellular calcium response to κ-opioid receptor stimulation in the rat heart

AJP Cell Physiology ◽

10.1152/ajpcell.1999.277.3.c492 ◽

1999 ◽

Vol 277 (3) ◽

pp. C492-C500 ◽

Cited By ~ 5

Author(s):

Jian-Ming Pei ◽

Xiao-Chun Yu ◽

Jin-Song Bian ◽

Tak-Ming Wong

Keyword(s):

Opioid Receptor ◽

Receptor Agonist ◽

Ventricular Myocytes ◽

High Concentration ◽

Receptor Stimulation ◽

Antagonistic Action ◽

Extracellular Acidosis ◽

Opioid Receptor Agonist ◽

Intracellular Ca ◽

First Time

To study the effects of κ-opioid receptor stimulation on intracellular Ca2+ concentration ([Ca2+]i) homeostasis during extracellular acidosis, we determined the effects of κ-opioid receptor stimulation on [Ca2+]iresponses during extracellular acidosis in isolated single rat ventricular myocytes, by a spectrofluorometric method. U-50488H (10–30 μM), a selective κ-opioid receptor agonist, dose dependently decreased the electrically induced [Ca2+]itransient, which results from the influx of Ca2+ and the subsequent mobilization of Ca2+ from the sarcoplasmic reticulum (SR). U-50488H (30 μM) also increased the resting [Ca2+]iand inhibited the [Ca2+]itransient induced by caffeine, which mobilizes Ca2+ from the SR, indicating that the effects of the κ-opioid receptor agonist involved mobilization of Ca2+ from its intracellular pool into the cytoplasm. The Ca2+responses to 30 μM U-50488H were abolished by 5 μM nor-binaltorphimine, a selective κ-opioid receptor antagonist, indicating that the event was mediated by the κ-opioid receptor. The effects of the agonist on [Ca2+]iand the electrically induced [Ca2+]itransient were significantly attenuated when the extracellular pH (pHe) was lowered to 6.8, which itself reduced intracellular pH (pHi) and increased [Ca2+]i. The inhibitory effects of U-50488H were restored during extracellular acidosis in the presence of 10 μM ethylisopropyl amiloride, a potent Na+/H+exchange blocker, or 0.2 mM Ni2+, a putative Na+/Ca2+exchange blocker. The observations indicate that acidosis may antagonize the effects of κ-opioid receptor stimulation via Na+/H+and Na+/Ca2+exchanges. When glucose at 50 mM, known to activate the Na+/H+exchange, was added, both the resting [Ca2+]iand pHi increased. Interestingly, the effects of U-50488H on [Ca2+]iand the electrically induced [Ca2+]itransient during superfusion with glucose were significantly attenuated; this mimicked the responses during extracellular acidosis. When a high-Ca2+ (3 mM) solution was superfused, the resting [Ca2+]iincreased; the increase was abolished by 0.2 mM Ni2+, but the pHi remained unchanged. Like the responses to superfusion with high-concentration glucose and extracellular acidosis, the responses of the [Ca2+]iand electrically induced [Ca2+]itransients to 30 μM U-50488H were also significantly attenuated. Results from the present study demonstrated for the first time that extracellular acidosis antagonizes the effects of κ-opioid receptor stimulation on the mobilization of Ca2+ from SR. Activation of both Na+/H+and Na+/Ca2+exchanges, leading to an elevation of [Ca2+]i, may be responsible for the antagonistic action of extracellular acidosis against κ-opioid receptor stimulation.

Multipartner Symbiosis across Biological Domains: Looking at the Eukaryotic Associations from a Microbial Perspective

mSystems ◽

10.1128/msystems.00148-19 ◽

2019 ◽

Vol 4 (4) ◽

Cited By ~ 2

Author(s):

Marta Turon ◽

Maria J. Uriz ◽

Daniel Martin

Keyword(s):

Bacterial Communities ◽

High Throughput Sequencing ◽

Marine Invertebrates ◽

Single Species ◽

Rrna Gene ◽

Polychaete Species ◽

Content Type ◽

Symbiotic Relationships ◽

Host Sponge ◽

Species Specific

ABSTRACTSponges establish tight associations with both micro- and macroorganisms. However, while studies on sponge microbiomes are numerous, nothing is currently known about the microbiomes of sponge-associated polychaetes and their relationships with those of their host sponges. We analyzed the bacterial communities of symbiotic polychaetes (Haplosyllisspp.) and their host sponges (Clathria reinwardti,Amphimedon paraviridis,Neofibularia hartmani, andAaptos suberitoides) to assess the influence of the sponges on the polychaete microbiomes. We identified both eukaryote partners by molecular (16S and COI genes) and morphological features, and we identified their microbial communities by high-throughput sequencing of the 16S rRNA gene (V4 region). We unravel the existence of sixHaplosyllisspecies (five likely undescribed) associated at very high densities with the study sponge species in Nha Trang Bay (central Vietnam). A single polychaete species inhabitedA. paraviridisand was different from the single species that inhabitedA. suberitoides. Conversely, two different polychaete species were found inC. reinwardtiandN. hartmani, depending on the two host locations. Regardless of the host sponge, polychaete microbiomes were species specific, which is a widespread feature in marine invertebrates. More than half of the polychaete bacteria were also found in the host sponge microbiome but at contrasting abundances. Thus, the associated polychaetes seemed to be able to select, incorporate, and enrich part of the sponge microbiome, a selection that appears to be polychaete species specific. Moreover, the bacterial diversity is similar in both eukaryotic partners, which additionally confirms the influence of food (host sponge) on the structure of the polychaete microbiome.IMPORTANCEThe symbiotic lifestyle represents a fundamental cryptic contribution to the diversity of marine ecosystems. Sponges are ideal targets to improve understanding the symbiotic relationships from evolutionary and ecological points of view, because they are the most ancient metazoans on earth, are ubiquitous in the marine benthos, and establish complex symbiosis with both prokaryotes and animals, which in turn also harbor their own bacterial communities. Here, we study the microbiomes of sponge-polychaete associations and confirm that polychaetes feed on their host sponges. The study worms select and enrich part of the sponge microbiome to shape their own species-specific bacterial communities. Moreover, worm microbiome diversity runs parallel to that of its food host sponge. Considering our results on symbiotic polychaetes and previous studies on fishes and mammals, diet appears to be an important source of bacteria for animals to shape their species-specific microbiomes.