Physiological Constraints Research Articles

Increased Suitability of Poleward Climate for a Tropical Butterfly (Euripus nyctelius) (Lepidoptera: Nymphalidae) Accompanies its Successful Range Expansion.

Distribution shifts are a common response in butterflies to a warming climate. Hong Kong has documented records of several new butterfly species in recent decades, comprising a high proportion of tropical species, some of which have successfully established. In this study, we examined possible drivers for the establishment of Euripus nyctelius Doubleday (Lepidoptera: Nymphalidae) by studying its thermal physiology and modeling current climate and future distributions projected by species distribution modeling (SDM). We found that E. nyctelius adults have a significantly higher critical thermal minimum than its local temperate relative, Hestina assimilis Linnaeus (Lepidoptera: Nymphalidae), suggesting a possible physiological constraint that may have been lifted with recent warming. SDMs provide further evidence that a shifting climate envelope may have improved the climate suitability for E. nyctelius in Hong Kong and South China—however, we cannot rule out the role of other drivers potentially influencing or driving range expansion, habitat change in particular. Conclusive attribution of warming-driven impacts for most tropical species is difficult or not possible due to a lack of historical or long-term data. Tropical insects will require a significant advancement in efforts to monitor species and populations across countries if we are to conclusively document climate-driven shifts in species distributions and manage the consequences of such species redistribution. Nevertheless, the warming climate and subsequent increased climatic suitability for tropical species in poleward areas, as shown here, is likely to result in future species redistribution events in subtropical and temperate ecosystems.

A biologging perspective to the drivers that shape gregariousness in dusky dolphins

Knowledge of proximate (causation and development) and ultimate (evolution and survival function) causes of gregariousness is necessary to advance our knowledge of animal societies. Delphinids are among the most social taxa; however, fine-scale understanding of their intra-specific relationships is hindered by the need for underwater observations on individuals. We developed a non-invasive animal-borne camera system with the goal of examining influences on gregariousness in dusky dolphins (Lagenorhynchus obscurus). We analyzed video and diving records from 11 individual dusky dolphins off Kaikoura, New Zealand. We examined the influence of biologger attachment on dolphin behavior and tested hypotheses regarding the effects of physiology, predation, and inter-individual variation on conspecific interactions. Dolphins did not exhibit increased rates of descent or ascent in the minutes immediately following biologger attachment, indicating a lack of behavioral response. Respiration rate was positively related to dive depth and duration, suggesting that diving is energetically expensive for this species. Gregariousness was negatively related to dive depth providing evidence that the physiological constraints of diving are likely to limit social behavior. Calves were not observed more frequently in infant (vs. echelon) position with increasing depth, highlighting the likelihood of other anti-predation strategies (e.g., dilution effect) in mother-calf pairs. We found that gregariousness differed between individuals within similar social groups, suggesting the importance of collecting data at the individual level. The evidence presented herein suggests that the further development of animal-borne camera systems will yield further insight into the mechanisms underlying delphinid social behavior. Dolphins are highly social and thus excellent model species for examining the cause and function of gregariousness. However, their cryptic nature poses a challenge to collecting the fine-scale data at the individual level required to conduct rigorous hypothesis tests. We overcame this obstacle by deploying a non-invasive cutting-edge biologger on free-ranging dusky dolphins to collect information on diving behavior, physiology, gregariousness, and mother-calf strategies. Results indicate that diving is energetically expensive, even to relatively shallow depths, and these costs likely hinder gregariousness at depth. Individual differences in gregariousness were apparent and as expected in this fission-fusion society. Unexpectedly, mother-calf pairs appeared to utilize strategies other than spatial positioning to minimize predation risk. This study advanced knowledge of dolphin social life and helps to improve the degree of data resolution in cetaceans to a level on par with terrestrial studies.

FORMULATION AND EVALUATION OF NIFEDIPINE SUSTAINED RELEASE TABLETS BY USING DIFFERENT POLYMERS

Oral drug delivery has been known for many years because the most generally utilized route of administration among all the routes that are explored for the general delivery of medication via various pharmaceutical products of different dosage forms. The reason that the oral route achieved such quality could also be partly attributed to its simple administration moreover because the ancient belief that by oral administration the drug is well absorbed because the food stuffs that area unit eaten daily. In fact the event of a pharmaceutical product for oral delivery, no matter its physical kind involves variable extents of optimization of dose kind characteristics at intervals the inherent constraints of GI physiology. The rationale for development of a extended release formulation of a drug is to enhance its therapeutic benefits, minimizing its side effects while improving the management of the diseased condition. The aim of the present investigation is to formulate and evaluate matrix tablets of Nifedipine using a mixture of polymers in view to sustain the drug release, reduce frequency of administration and improved patient compliance. In this research paper all evaluation parameter and stability studies also well discussed in well manner.
 Keyword: Matrix Tablets, Coating, Novel Drug Delivery System, Sustained Release Tablets

Effects of temperature and meal size on the postprandial metabolic response of Leptodactylus latrans (Anura, Leptodactylidae).

The postprandial increment of metabolism, often referred to as specific dynamic action (SDA), encompasses the summed costs of meal ingestion, digestion, absorption, and assimilation. Different SDA parameters, such as its magnitude, duration, and relative cost, are affected by a diverse set of environmental and physiological determinants, including meal size and body temperature. While the influence of these variables has been thoroughly examined in most ectothermic vertebrate groups, few studies have focused on the determinants and consequences of the SDA response in anuran amphibians. Thus, we examined the effects of meal size and body temperature on the SDA response of a Neotropical frog, Leptodactylus latrans, by measuring the rates of oxygen consumption of frogs while fasting and after being fed meals of different sizes at different temperatures. SDA lasted from 3 to 5 days and increased with meal size for frogs fed meals equivalent to 5-15% of their body mass. SDA cost was not affected by meal size and averaged 14.6% of the caloric content of the meal. Temperature increment was accompanied by proportional increases in metabolic rate and shorter SDA duration. The relative SDA cost averaged 14.8% of the meal caloric content at 20°C and 25°C, but increased to 23.5% at 30°C. Our results indicate that meal size imposes no physiological or energetic constraint to L. latrans feeding. Digestion at temperatures near the thermal preference of the species seems to optimize energetic return, whereas the shortening of SDA duration at higher temperatures may provide significant ecological advantages.

The dive performance of immature king penguins following their annual molt suggests physiological constraints.

Like all birds, penguins undergo periodic molt, during which they replace old feathers. However, unlike other birds, penguins replace their entire plumage within a short period while fasting ashore. During molt, king penguins (Aptenodytes patagonicus) lose half of their initial body mass, most importantly their insulating subcutaneous fat and half of their pectoral muscle mass. The latter might challenge their capacity to generate and sustain a sufficient mechanical power output to swim to distant food sources and propel themselves to great depth for successful prey capture. To investigate the effects of the annual molt fast on their dive/foraging performance, we studied various dive/foraging parameters and peripheral temperature patterns in immature king penguins across two molt cycles, after birds had spent their first and second year at sea, using implanted data-loggers. We found that the dive/foraging performance of immature king penguins was significantly reduced during post-molt foraging trips. Dive and bottom duration for a given depth were shorter during post-molt and post-dive surface interval duration was longer, reducing overall dive efficiency and underwater foraging time. We attribute this decline to the severe physiological changes that birds undergo during their annual molt. Peripheral temperature patterns differed greatly between pre- and post-molt trips, indicating the loss of the insulating subcutaneous fat layer during molt. Peripheral perfusion, as inferred from peripheral temperature, was restricted to short periods at night during pre-molt but occurred throughout extended periods during post-molt, reflecting the need to rapidly deposit an insulating fat layer during the latter period.

Seasonal changes in basking shark vertical space use in the north-east Atlantic

Mobile marine species can exhibit vast movements both horizontally and vertically. Spatial analysis of vertical movements may help improve an understanding of the processes that influence space use. Previously, vertical space use of basking sharks (Cetorhinus maximus) in the north-east Atlantic described movements largely within waters of the continental shelf during summer and autumn months, with few records of detailed vertical behaviour during winter. We use archival satellite telemetry data from 32 basking sharks (12 females, 6 males, and 14 of unknown sex measuring 4–5 m (n = 6), 5–6 m (n = 10), 6–7 m (n = 7), 7–8 m (n = 8), and 8–9 m (n = 1) estimated total length) tracked over 4 years (2012–2015). The satellite tags provided depth and temperature data for a cumulative 4489 days (mean 140 ± 97 days per shark, range 10–292 days) to describe vertical space use and thermal range of basking sharks in the north-east Atlantic. Basking sharks exhibit seasonality in vertical space use, revealing repeated ‘yo-yo’ movement behaviour with periods of occupancy at depths greater than 1000 m in late winter/early spring. Describing seasonal vertical space use in marine megavertebrates can increase knowledge of movements throughout their environment including physiological and morphological constraints to movement, nutrient transfer, and overlap with anthropogenic threats to inform future conservation strategies.

Towards a moss sclerophylly continuum: Evolutionary history, water chemistry and climate control traits of hygrophytic mosses

Abstract Mosses are amongst the oldest and simplest plants, they can be found almost everywhere in the world, and they condition the structure and function of many ecosystems. Their sensitivity to environmental changes makes them very interesting subjects of study in ecology, and understanding them can provide insights into the evolutionary history of plants. However, the study of moss traits and their relationship with their environment is far behind that of vascular plants. We sampled 303 assemblages of aquatic and semi‐aquatic (hygrophytic) mosses growing in semi‐natural springs distributed around the northeast of the Iberian Peninsula to study how moss traits vary depending on their evolutionary history, climate and water chemistry. To do so, we analysed 30 moss species and 17 traits using phylogenetic comparative methods and an extended RLQ analysis, accounting for spatial and phylogenetic information. We hypothesized that there is a sclerophylly continuum in mosses living across a gradient of high and low water conductivity springs that may mimic sclerophylly in vascular plants that live in stressful environments. Results indicated that life‐forms and, especially, morphological traits were well preserved phylogenetically and responsive to water chemistry and climate. That combined with spatial autocorrelation in environmental variables resulted in a clustered distribution of phylogenetically closely related mosses in space. Mosses living in springs with a warm and dry climate that discharge hard water mainly presented species with needle‐like leaves, were denser, and had lower water absorption capacity. The opposite was found in cold, humid and soft water springs. Synthesis. Our results suggest that climate and water chemistry are main determinants of traits of hygrophytic mosses and of species distributions. We found evidence of a potential sclerophylly continuum in moss traits, which we hypothesize may be mainly related to physical and physiological constraints produced by water chemistry. Our findings describe moss sclerophylly in a gradient of water conductivity similar to that found in vascular plants with water availability and temperature. Further experimental studies will be required to confirm the observations found in this study. A free Plain Language Summary can be found within the Supporting Information of this article.

Adult achondroplasia patient with extensive long segment severe C1 to C6 segment spinal canal stenosis: Unique presentation

Achondroplasia represents the common variety of skeletal dysplasia causing short-limb dwarfism. It may be associated with congenial craniovertebral junction anomaly, including atlantoaxial dislocation, Os odointoideum or basilar invagination or acquired as a result of the previous foramen magnum region surgery. However, long segment cervical compression from the first cervical vertebra region to sixth cervical region, such extensive compression producing myelopathy is not reported, and current case represents first case in the western literature. He was managed surgically with a good outcome. Perioperative management along with brief review of pertinent literature along with the management of such case is discussed in brief. Anesthetic management of such patient with coexisting extensive cervical compression presents unique challenges in view of the multisystem involvement along with preexisting anatomical and physiological constraints.

Gestural Properties of the Non-Target Velar Stop /k/ and Its Variance with Respect to Supralaryngeal Constrictions in C2

In this study, we examine overlap-induced gestural properties in C1. Specifically, we examine the spatio-temporal properties of the non-target velar stop /k/ in Korean, as a function of three segmental contexts in C2 (pre-/h/, pre-/p/, and pre-/t/), two-boundary conditions, and two speech-rate conditions. The results show that gestural overlap with different supralaryngeal constrictions in C2 is positively correlated with the constriction duration of /k/, and is negatively correlated with the constriction maxima. Different constrictions in C2 distinctly affect the spatio-temporal properties of C1. The pre-/t/ context leads to distinct patterns in the C1 velar stop, compared to the pre-/h/ and pre-/p/ contexts. The pre-/t/ velar stops observed in most combinatoric phonological contexts have shorter constriction durations, and have greater constriction maxima for /k(#)t/. Greater constriction maxima is also observed for the within-word condition as well as for fast speech rate. The contradictory spatio-temporal properties of /k/ seem to be determined by physiological constraints on a consecutive lingual-lingual sequence, and by a higher jaw position facilitated by a coronal.

They are young, and they are many: dating freshwater lineages in unicellular dinophytes.

Dinophytes are one of few protist groups that have an extensive fossil record and are therefore appropriate for time estimations. However, insufficient sequence data and strong rate heterogeneity have been hindering to put dinophyte evolution into a time frame until now. Marine-to-freshwater transitions within this group are considered geologically old and evolutionarily exceptional due to strong physiological constraints that prevent such processes. Phylogenies based on concatenated rRNA sequences (including 19 new GenBank entries) of two major dinophyte lineages, Gymnodiniaceae and Peridiniales, were carried out using an uncorrelated molecular clock and five calibration points based on fossils. Contrarily to previous assumptions, marine-to-freshwater transitions are more frequent in dinophytes (i.e. five marine-freshwater transitions in Gymnodiniaceae, up to ten but seven strongly supported transitions in Peridiniales), and none of them occurred as early as 140 MYA. Furthermore, most marine-to-freshwater transitions, and the followed diversification, took place after the Cretaceous-Paleogene boundary. Not older than 40 MYA, the youngest transitions within Gymnodiniaceae and Peridiniales occurred under the influence of the Eocene climate shift. Our evolutionary scenario indicates a gradual diversification of dinophytes without noticeable impact of catastrophic events, and their freshwater lineages have originated several times independently at different points in time.

Developmental effects of heatwave conditions on the early life stages of a coral reef fish.

Marine heatwaves, which are increasing in frequency, duration and intensity owing to climate change, are an imminent threat to marine ecosystems. On coral reefs, heatwave conditions often coincide with periods of peak recruitment of juvenile fishes and exposure to elevated temperature may affect their development. However, whether differences in the duration of high temperature exposure have effects on individual performance is unknown. We exposed juvenile spiny damselfish, Acanthochromis polyacanthus, to increasing lengths of time (3, 7, 30 and 108 days post-hatching) of elevated temperature (+2°C). After 108 days, we measured escape performance at present-day control and elevated temperatures, standard length, mass and critical thermal maximum. Using a Bayesian approach, we show that 30 days or more exposure to +2°C leads to improved escape performance, irrespective of performance temperature, possibly owing to developmental effects of high temperature on muscle development and/or anaerobic metabolism. Continued exposure to elevated temperature for 108 days caused a reduction in body size compared with the control, but not in fish exposed to high temperature for 30 days or less. By contrast, exposure to elevated temperatures for any length of time had no effect on critical thermal maximum, which, combined with previous work, suggests a short-term physiological constraint of ∼37°C in this species. Our study shows that extended exposure to increased temperature can affect the development of juvenile fishes, with potential immediate and future consequences for individual performance.

Intraspecific Energetic Trade-Offs and Costs of Encephalization Vary from Interspecific Relationships in Three Species of Mormyrid Electric Fishes

The evolution of increased encephalization comes with an energetic cost. Across species, this cost may be paid for by an increase in metabolic rate or by energetic trade-offs between the brain and other energy-expensive tissues. However, it remains unclear whether these solutions to deal with the energetic requirements of an enlarged brain are related to direct physiological constraints or other evolved co-adaptations. We studied the highly encephalized mormyrid fishes, which have extensive species diversity in relative brain size. We previously found a correlation between resting metabolic rate and relative brain size across species; however, it is unknown how this interspecific relationship evolved. To address this issue, we measured intraspecific variation in relative brain size, the sizes of other organs, metabolic rate, and hypoxia tolerance to determine if intraspecific relationships between brain size and organismal energetics are similar to interspecific relationships. We found that 3 species of mormyrids with varying degrees of encephalization had no intraspecific relationships between relative brain size and relative metabolic rate or relative sizes of other organs, and only 1 species had a relationship between relative brain size and hypoxia tolerance. These species-specific differences suggest that the interspecific relationship between metabolic rate and relative brain size is not the result of direct physiological constraints or strong stabilizing selection, but is instead due to other species level co-adaptations. We conclude that variation within species must be considered when determining the energetic costs and trade-offs underlying the evolution of extreme encephalization.

Selection of Cyanobacterial (Synechococcus sp. Strain PCC 6301) RubisCO Variants with Improved Functional Properties That Confer Enhanced CO2-Dependent Growth of Rhodobacter capsulatus, a Photosynthetic Bacterium.

Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a ubiquitous enzyme that catalyzes the conversion of atmospheric CO2 into organic carbon in primary producers. All naturally occurring RubisCOs have low catalytic turnover rates and are inhibited by oxygen. Evolutionary adaptations of the enzyme and its host organisms to changing atmospheric oxygen concentrations provide an impetus to artificially evolve RubisCO variants under unnatural selective conditions. A RubisCO deletion strain of the nonsulfur purple photosynthetic bacterium Rhodobacter capsulatus was previously used as a heterologous host for directed evolution and suppressor selection studies that led to the identification of a conserved hydrophobic region near the active site where amino acid substitutions selectively impacted the enzyme's sensitivity to O2 In this study, structural alignments, mutagenesis, suppressor selection, and growth complementation with R. capsulatus under anoxic or oxygenic conditions were used to analyze the importance of semiconserved residues in this region of Synechococcus RubisCO. RubisCO mutant substitutions were identified that provided superior CO2-dependent growth capabilities relative to the wild-type enzyme. Kinetic analyses of the mutant enzymes indicated that enhanced growth performance was traceable to differential interactions of the enzymes with CO2 and O2 Effective residue substitutions also appeared to be localized to two other conserved hydrophobic regions of the holoenzyme. Structural comparisons and similarities indicated that regions identified in this study may be targeted for improvement in RubisCOs from other sources, including crop plants.IMPORTANCE RubisCO catalysis has a significant impact on mitigating greenhouse gas accumulation and CO2 conversion to food, fuel, and other organic compounds required to sustain life. Because RubisCO-dependent CO2 fixation is severely compromised by oxygen inhibition and other physiological constraints, improving RubisCO's kinetic properties to enhance growth in the presence of atmospheric O2 levels has been a longstanding goal. In this study, RubisCO variants with superior structure-functional properties were selected which resulted in enhanced growth of an autotrophic host organism (R. capsulatus), indicating that RubisCO function was indeed growth limiting. It is evident from these results that genetically engineered RubisCO with kinetically enhanced properties can positively impact growth rates in primary producers.

The Vocalist in the Crib: the Flexibility of Respiratory Behaviour During Crying in Healthy Neonates

To evaluate the flexibility of respiratory behavior during spontaneous crying using an objective analysis of temporal measures in healthy neonates. A total of 1,375 time intervals, comprising breath cycles related to the spontaneous crying of 72 healthy, full-term neonates (35 females) aged between two and four days, were analyzed quantitatively. Digital recordings (44 kHz, 16 bit) of cries emitted in a spontaneous, pain-free context were obtained at the University Children's Hospital Wurzburg. The amplitude-by-time representation of PRAAT: doing phonetics by computer (38) was used for the manual segmentation of single breath-cycles involving phonation. Cursors were set in these time intervals to mark the duration of inspiratory (IPh) and expiratory phases (EPh), and double-checks were carried out using auditory analyses. A PRAAT script was used to extract temporal features automatically. The only intervals analyzed were those that contained an expiratory cry utterance embedded within preceding and subsequent inspiratory phonation (IP). Beyond the reliable identification of IPh and EPh, this approach also guaranteed inter-individual and inter-utterance homogenization with respect to inspiratory strength and an unconstructed vocal tract. Despite the physiological constraints of the neonatal respiratory system, a high degree of flexibility in the ratio of IPh/EPh was observed. This ratio changed hyperbolically (r = 0.71) with breath-cycle duration. Descriptive statistics for all the temporal measures are reported as reference values for future studies. The existence of respiratory exploration during the spontaneous crying of healthy neonates is supported by quantitative data. From a clinical perspective, the data demonstrate the presence of a high degree of flexibility in the respiratory behavior, particularly neonates' control capability with respect to variable cry durations. These data are discussed in relation to future clinical applications.

Global patterns of body size evolution are driven by precipitation in legless amphibians

Body size shapes ecological interactions across and within species, ultimately influencing the evolution of large‐scale biodiversity patterns. Therefore, macroecological studies of body size provide a link between spatial variation in selection regimes and the evolution of animal assemblages through space. Multiple hypotheses have been formulated to explain the evolution of spatial gradients of animal body size, predominantly driven by thermal (Bergmann's rule), humidity (‘water conservation hypothesis’) and resource constraints (‘resource rule’, ‘seasonality rule’) on physiological homeostasis. However, while integrative tests of all four hypotheses combined are needed, the focus of such empirical efforts needs to move beyond the traditional endotherm–ectotherm dichotomy, to instead interrogate the role that variation in lifestyles within major lineages (e.g. classes) play in creating neglected scenarios of selection via analyses of largely overlooked environment–body size interactions. Here, we test all four rules above using a global database spanning 99% of modern species of an entire Order of legless, predominantly underground‐dwelling amphibians (Gymnophiona, or caecilians). We found a consistent effect of increasing precipitation (and resource abundance) on body size reductions (supporting the water conservation hypothesis), while Bergmann's, the seasonality and resource rules are rejected. We argue that subterranean lifestyles minimize the effects of aboveground selection agents, making humidity a dominant selection pressure – aridity promotes larger body sizes that reduce risk of evaporative dehydration, while smaller sizes occur in wetter environments where dehydration constraints are relaxed. We discuss the links between these principles with the physiological constraints that may have influenced the tropically‐restricted global radiation of caecilians.

Immunolocalization of β-(1–4)-D-galactan, xyloglucans and xylans in the reaction xylem fibres of Leucaena leucocephala (Lam.) de Wit

Cell wall architecture of tension wood fibres represents a suitable biological system to study the mechanism of growth and maintenance of posture of trees growing under various physical and physiological growth constraints. In the present study, we investigated the spatial distributions of β-(1–4)-D-galactan, xyloglucan and xylans (both less and highly substituted) in the opposite and tension wood fibres of bent Leucaena leucocephala by immunolabelling with monoclonal antibodies LM5, CCRCM1, LM10 and LM11 specific to these carbohydrate epitopes. The presence of non-lignified, tertiary wall layer is the typical tension wood characteristic associated with the reaction xylem fibres in Leucaena. LM5 labelling of opposite fibres showed weak labelling in the cell walls indicating less concentration of β-(1–4)-D-galactans while tension wood showed strong labelling in the tertiary wall layer suggesting the gelatinous layer (G-layer) has a strong cross linking with β-(1–4)-D-galactans. Xyloglucan distribution was more in the compound middle lamellae and the primary wall-S1 layer boundary of tension wood fibres as compared to that of opposite wood. A weak labelling was also evident near the boundary between the G-layer and the secondary wall of tension wood fibres. The secondary wall of opposite and tension wood fibres showed a strong distribution of both ls ACG Xs (LM10) and hs ACG Xs (LM11) while a weak labelling was noticed in the compound middle lamella. Tension wood fibres also showed strong xylan labelling mainly confined to the lignified secondary walls while the G-layer showed weak xylan labelling. In conclusion, our results suggest that β-(1–4)-D-galactans and xyloglucans could be implicated in the tensile stress generation within the G-layer of tension wood fibres of Leucaena leucocephala.

Similarities and differences in constraints and constraint negotiation among Japanese sport tourists: a case of masters games participants

ABSTRACTThe purposes of this study were to examine (a) similarities and differences in constraints to and constraint negotiation for masters games (MG) participation, and (b) the relationships among constraints, constraint negotiation, and intention to participate in the World Masters Games 2021 Kansai, across international sport tourists, domestic sport tourists, and sport excursionists. An online survey was conducted with 449 Japanese people who participated in MGs within the last three years. Our results indicated that international sport tourists experienced higher levels of psychological, physiological, interpersonal, financial, tourism, commitment, MG-specific constraints than domestic sport tourists and sport excursionists, although physiological constraints did not differ between international and domestic sport tourists. Conversely, international and domestic sport tourists utilized tourism and MG-self-adaptation negotiation strategies more than sport excursionists. Lastly, constraints to and constraint negotiation for the past MG were not related to the intention of participation in the World Masters Games 2021 Kansai across the three groups. These results suggest that this typology of sport tourists – international, domestic, and excursionist – is an effective framework to understand constraints and negotiation as well as other behaviors and experiences of Japanese sport tourists.

EFFECTS OF SEASONAL AIR TEMPERATURES AND LIGHT ON LEAF TRAITS AT ATLANTIC MONTANE FOREST, BRAZILIAN SOUTHEAST

Seasonal variation of temperature could place physiological constraints on the distribution and performance of tropical forest plants, associated with light and water availability. A simple way to assess the relationship between temperature and plant physiology is through the characterization of leaf traits. The main aim of this study was to evaluate, through foliar parameters, the responses of plants to inherent seasonality. A 0.09 ha plot was installed near the flux tower and albedo sensors at Montane Ombrophilous Dense Forest (MODF) - Santa Virgínia Nucleus. At the peak of the dry and wet seasons, the electron transport rate (ETR) and photosynthetic pigments were measured. The results indicated that in MODF, cold and light availability are the main factors that could be influencing the physiology of species, demonstrated by high ETR in the wet season (197.4 µmol e-m-2s-1) compared to the dry season (87.4 µmol e-m-2s-1). Photosynthetic pigments varied between seasons, we observed higher chlorophyll b content (p<0.05), and lower content of carotenoids and xanthophylls (p<0.01) and Chl a/b (p<0.01) in the dry season. The low temperatures and irradiance influenced metabolic activity.

Influence of performance running footwear on muscle soreness and damage

The Nike Zoom Vaporfly 4% shoe has been suggested to significantly improve running economy and thus greatly attenuate the metabolic perturbation and physiological constraint associated with maratho...

Loss of the HIF pathway in a widely distributed intertidal crustacean, the copepod Tigriopus californicus.

Hypoxia is a major physiological constraint for which multicellular eukaryotes have evolved robust cellular mechanisms capable of addressing dynamic changes in O2 availability. In animals, oxygen sensing and regulation is primarily performed by the hypoxia-inducible factor (HIF) pathway, and the key components of this pathway are thought to be highly conserved across metazoans. Marine intertidal habitats are dynamic environments, and their inhabitants are known to tolerate wide fluctuations in salinity, temperature, pH, and oxygen. In this study, we show that an abundant intertidal crustacean, the copepod Tigriopus californicus, has lost major genetic components of the HIF pathway, but still shows robust survivorship and transcriptional response to hypoxia. Mining of protein domains across the genome, followed by phylogenetic analyses of gene families, did not identify two key regulatory elements of the metazoan hypoxia response, namely the transcription factor HIF-α and its oxygen-sensing prolyl hydroxylase repressor, EGLN Despite this loss, phenotypic assays revealed that this species is tolerant to extremely low levels of available O2 for at least 24 h at both larval and adult stages. RNA-sequencing (seq) of copepods exposed to nearly anoxic conditions showed differential expression of over 400 genes, with evidence for induction of glycolytic metabolism without a depression of oxidative phosphorylation. Moreover, genes involved in chitin metabolism and cuticle reorganization show categorically a consistent pattern of change during anoxia, highlighting this pathway as a potential solution to low oxygen availability in this small animal with no respiratory structures or pigment.