Morpho-anatomical Changes Research Articles

Morphoanatomical alterations in extrafloral nectaries of Cedrela fissilis Vell. (Meliaceae), a native species of the Atlantic Forest, in response to simulated acid rain

Acid rain is one of the major contributors to the loss of tropical forest. Although the effects of acid rain in leaf anatomy have been widely studied, its impact on specialized secretory structures remains unknown. The aim of this study was to investigate the morphoanatomical changes in the extrafloral nectaries of Cedrela fissilis in response to simulated acid rain. Each seedling was sprayed with 50 ml of an acidic solution daily for 19 consecutive days. Anatomical and micromorphological changes in the nectaries were described. The treated plants exhibited plasmolysis and disruption of epidermal cells, cell collapse, hypertrophy, plasmolysis, phenolic and starch accumulation in the nectar-secreting cells, and the formation of a wound healing tissue. The results indicate that the nectaries of C. fissilis undergo alterations when exposed to acid rain, which may compromise the functioning of the entire structure and potentially impact plant-insect ecological interactions.

A Modeling Approach to Studying the Influence of Grafting on the Anatomical Features and SAUR Gene Expression in Watermelons

Grafting alters the genetic and anatomical features of plants. Although grafting has been widely applied in plant propagation, the underlying processes that govern the effects of the procedure are not fully understood. Samples were collected to study the long-term influence of grafting on the leaf-shoot morphology, leaf-shoot anatomy, and genetic signature of the grafted plants. Citrulus lanatus (Thunb.) Matsum. & Nakai (cv. Lady) was used as the scion, and Lagenaria siceraria (Molina) Standl (cv. Argentario) as a rootstock. In grafted plants, leaf blades and petioles were 20.92% and 12.82% longer, respectively, while the midrib collenchyma was 35.68% thicker, and the diameter of the vessel member was 11.17% larger than in ungrafted plants. In the stem, grafting affected the arrangement and number of vascular bundles (from 1 to 2 rings). The thickness of the epidermis decreased by 69.79%, and the size of the external fascicular phloem decreased by 23.56%. The diameter of the vessel member of the grafted plants increased by 28.94%. Eight out of ten evaluated primers met the requirements (stability in both watermelons and bottle gourd, tissue-specific). In the genetic tests, we examined whether this change in the gene expression pattern is due to the grafting and, if so, to what extent. Seven out of eight tested Small Auxin Up-Regulated RNA (SAUR) genes were expressed in the ungrafted and grafted C. lanatus lines in four cases; the expression increased by more than 10% after grafting. The morpho-anatomical changes and genetic variation reported in this study for grafted lines of C. lanatus contribute to the understanding of the underlying mechanisms of plant growth observations resulting from grafting.

Multicontamination Toxicity Evaluation in the Model Plant Lactuca sativa L.

Many contaminated soils contain several toxic elements (TEs) in elevated contents, and plant-TE interactions can differ from single TE contamination. Therefore, this study investigated the impact of combined contamination (As, Cd, Pb, Zn) on the physiological and metabolic processes of lettuce. After 45 days of exposure, TE excess in soil resulted in the inhibition of root and leaf biomass by 40 and 48%, respectively. Oxidative stress by TE accumulation was indicated by markers-malondialdehyde and 5-methylcytosine-and visible symptoms of toxicity (leaf chlorosis, root browning) and morpho-anatomical changes, which were related to the change in water regime (water potential decrease). An analysis of free amino acids (AAs) indicated that TEs disturbed N and C metabolism, especially in leaves, increasing the total content of free AAs and their families. Stress-induced senescence by TEs suggested changes in gas exchange parameters (increase in transpiration rate, stomatal conductance, and intercellular CO2 concentration), photosynthetic pigments (decrease in chlorophylls and carotenoids), a decrease in water use efficiency, and the maximum quantum yield of photosystem II. These results confirmed that the toxicity of combined contamination significantly affected the processes of lettuce by damaging the antioxidant system and expressing higher leaf sensitivity to TE multicontamination.

3D analysis of condylar and mandibular remodeling one year after intra-oral ramus vertical lengthening osteotomy.

Among the existing techniques for the correction of mandibular posterior vertical insufficiency (PVI), the intra-oral ramus vertical lengthening osteotomy (IORVLO) can be proposed as it allows simultaneous correction of mandibular height and retrusion. This study assessed the 3D morpho-anatomical changes of the ramus-condyle unit and occlusal stability after IORVLO. This retrospective analysis compared immediate and 1-year post-operative 3D CBCT reconstructions. The analysis focused on the condylar height (primary endpoint) and on the changes in condylar (condylar diameter, condylar axis angle) and mandibular (ramus height, Frankfort-mandibular plane angle, gonion position, intergonial distance, angular remodeling) parameters. Additionally, this analysis investigated the maxillary markers and occlusal stability. On the 38 condyles studied in 21 included patients (mean age 23.7 ± 3.9years), a condylar height (CH) loss of 0.66mm (p < 0,03) was observed, with no correlation with the degree of ramus lengthening (mean 13.3 ± 0.76mm). Only one patient presented an occlusal relapse of Class II, but a 3.4mm (28%) condylar diameter loss and a 33% condylar volume reduction with loss of 1mm and 3.4mm in CH and condyle diameter, respectively. A mean 3.56mm (p < 0.001) decrease in ramus height was noted, mainly due to bone resorption in the mandibular angles. This study confirms the overall stability obtained with IORVLO for the correction of PVI. This study aims to precise indication of IORVLO, and to validate the clinical and anatomical stability of results.

Blue light strongly promotes de-etiolation over green, moderate over red, but have limited action over far-red lights in lettuce plants

The role of photoreceptors (phytochromes and cryptochromes) was evaluated in lettuce regarding (de)etiolation processes. The manipulation of light quality and intensity can modulate their activity and response and, consequently, promote morphophysiological changes in plants. To this end, lettuce plants were grown under controlled conditions at two photosynthetically active radiation levels (300 and 600 µmol m−2 s−1) and at different qualities, including white, blue, green, red and far-red light, as well as combinations, totaling 18 treatments. Biomass gain, internode length, light interception, pigment content, morpho-anatomical changes in the leaves and ultrastructural changes in the chloroplast and cell wall were evaluated. It was verified that in green, there was the highest degree of etiolation; however, the supplementation of blue promotes a strong de-etiolation process. In pure red (R), the plants were slightly less etiolated, but with limited action of blue in stimulating de-etiolation, and in R plus far-red (FR) (R:FR ratio was 0.33 in R + FR treatment), there was a strong degree of etiolation and weak action of blue on those set of treatments. In general, the plants submitted to the highest intensities of blue light, alone or in combination, approach the control phenotype (white light at total 300 µmol m−2 s−1; 18 % blue = 54 µmol m−2 s−1). The morpho-anatomical phenotype supports the hypothesis that blue light is capable of inhibiting or reducing etiolation-related responses, but the effects are dependent not only on the quality alone but also on the light intensity. Based on the known light-dependent response of phytochromes and cryptochromes, we suggest a weak interference of PHYB on CRY and a strong negative action of PHYA on CRY proteins.

Craniological features of the American mink in south-eastern Belarus

A series of skulls (n = 27) of the American mink (Neogale vison) from the south-east of Belarus (Gomel region, floodplain of the Sozh River) was studied. The animals were caught by different hunters in 2000–2004. The sex of individuals was not determined. When examining the skull, only the most pronounced morpho-anatomical changes that can be diagnosed confidently as deviations from the norm were taken into account. In all cases, lamellar deposition of calcium salts in the area of tentorium cerebelli osseum inside the cranial vault was detected. The growing plate length reached half of the arch height in some individuals. These traits (considerable area of bone plates; presence of a sharp spine growing in different plains) allow suggesting that the analysed growths are of pathological origin. This pathology can considerably affect the viability and physiological status of individuals as it disrupts the functioning of the central nervous system. It is difficult to identify the cause of intracranial calcifications due to the possible effect of factors of various nature. Some degree of calcification of the opisthion region of foramen magnum was found. The changes occurred in the foramen shape cannot be considered phenetic variability. In most individuals, the thinning of maxillary bone in the teeth roots area is observed. However, we believe that the identified degree of bone tissue thinning is not critical and therefore does not affect the life expectancy of individuals. Two adult individuals have swelling of the maxillary bone. In one case, an extensive bone tissue excavation was identified on the left lower jaw, which led to the loss of the canine tooth. The analysed pathomorphological change is not of traumatic nature because in case of post-traumatic osteomyelitis sequesters (separating fragments) are formed. It is necessary to further analyse the American mink skulls available at scientific collections of Belarus and to identify the degree of calcium salt deposits and their impact on the foramen magnum phenotypes. We consider it necessary to create an annotated catalogue of pathologies and anomalies of the skull of the American mink in the south-east of Belarus and adjacent territories of Ukraine, since the morphological method is essential in the diagnosis of bone tissue diseases.

MICROMORPHOLOGICAL AND ANATOMICAL RESPONSES OF NATIVE DICOTS TO INDUSTRIAL EFFLUENTS RELEASED FROM CONTAMINATED REGION OF THE CHENAB RIVER IN PAKISTAN

Faisalabad industrial units discharge effluents and associated toxic chemicals into the environment, deteriorating ecological conditions and ecosystem health. Morphoanatomical changes in some medicinally important native species (Calotropis procera, Eclipta alba, Phyla nodiflora, and Ranunculus sceleratus) exposed to heavy industrial pollution gained evaluation. These species of choice were due to their widespread distribution in the area. Ten sites selected in the River Chenab, Chiniot, had three near point source pollution of Faisalabad industries within the 500-m radius (polluted) at three drains and two sites inside the river after each drain point source with the control site at 14 km after from the first industrial drain point source. The general response of all plants to effluents was growth retardation. Plant height increased significantly in all species from river sites. An increase in tallness was more prominent in species like C. procera and P. nodiflora. An increase in stem sclerification in C. procera and E. alba from polluted sites occurred, which indicated a better ability to tolerate industrial pollution. Remarkable increases in stem and leaf epidermis, intensive stem sclerenchyma, and closely packed stem vascular bundles in C. procera appeared, which could increase resistance to industrial pollution. Most of the morphoanatomical parameters notably attained a decrease in E. alba, the most vulnerable species. Plant survival depends on particular structural changes in dermal, mechanical, parenchymatous, and vascular tissues. Overall, industrial pollution adversely impacts plant morphological and micromorphological features, although the reaction of specific species to industrial contamination varies. The study determined that stem and leaf anatomical features, such as, epidermis size and storage tissue thickness, are suitable morphoanatomical markers for industrial pollution biomonitoring. Internal modifications of plants vegetating different industrial contaminated sites played a significant role in high tolerance levels.

Evaluation of morpho-anatomical changes in culinary herbs in response to cadmium and lead to explore their role in phytoremediation

Evaluation of morpho-anatomical changes in culinary herbs in response to cadmium and lead to explore their role in phytoremediation

Morphoanatomical Changes in Eucalyptus grandis Leaves Associated with Resistance to Austropuccinia psidii in Plants of Two Ages.

The fungus Austropuccinia psidii infects young tissues of Eucalyptus plants until they are two years old in the nursery and field, causing Myrtaceae rust. The characteristics making older eucalypt leaves resistant to A. psidii and the reason for the low levels of this pathogen in older plants need evaluations. The aim of this study was to evaluate the morphological differences between Eucalyptus grandis leaves of different growth stages and two plant ages to propose a visual phenological scale to classify E. grandis leaves according to their maturation stages and to evaluate the time of leaf maturation for young and adult plants. A scale, based on a morphological differentiation for E. grandis leaves, was made. The color, shape and size distinguished the leaves of the first five leaf pairs. Anatomical analysis showed a higher percentage of reinforced tissue, such as sclerenchyma-like tissue and collenchyma, greater leaf blade thickness, absence of lower palisade parenchyma in the mature leaves and a higher number of cavities with essential oils than in younger ones. Changes in anatomical characteristics that could reduce the susceptibility of older E. grandis leaves to A. psidii coincide with the time of developing leaf resistance. Reduced infection of this pathogen in older plants appears to be associated with a more rapid maturation of their leaf tissues.

Comparative Root Morpho-Anatomical Studies On Meloidogyne Graminicola Resistant And Susceptible Rice Genotypes

The work characterizes root morpho-anatomical changes in rice due to infestation of rice root-knot nematode, Meloidogyne graminicola. The susceptible rice genotype, Satabdi (IET-4786) and resistant rice genotypes Marichsal and Lakshmansal were inoculated with three different geographic isolates of M. graminicola viz., Mg1 (Ashui, West Medinipur), Mg2 (Sumitrapur, West Medinipur) and Mg3 (Gayeshpur, Nadia). The results of demonstrated that, transverse section of morpho-anatomical structure of Mg1 isolate inoculated root at 25 DAI to susceptible and resistant rice genotypes viz., Satabdi and Marichsal showed presence of adult females and egg-mass in the cortex which symbolized a successful host parasitic relationship. Organization of cellular architecture of adventitious root of rice genotypes Satabdi and Marichsal when inoculated with Mg2 isolate then nematode infestation led to drastic changes as evidenced by the disorganization of cortical cells along with dissolution of epidermal, exodermal and sclerenchymatous cells at 10 DAI. The rice genotype, Lakshmansal did not reveal any changes in the root morpho-anatomy when inoculated with Mg2 isolate at 10 DAI. The cross section of the roots of Satabdi and Marichsal revealed complete obliteration of root anatomical structures along with formation of multinucleate giant cells, cavities in the stele owing to nematode injury along with females and egg-masses at 10 and 25 DAI of Mg3 isolate. The rice genotype Lakshmansal, was characterized as resistant against all three isolates of Mg as confirmed by histological study of roots. Cortical thickness of uninfected rice roots was comparatively lesser than infected ones, while maximum stele diameter was recorded with Marichsal when inoculated with Mg1 isolate i.e. 523.01 µm at 25 DAI. Outer portion of the root was also less than infected ones. Giant cell diameter of Satabdi and Marichsal ranged from 43.45-107.46 µm and 30.68-102.67 µm, respectively, indicating successful establishment of host-nematode interaction.

Comparative anatomy and genetic bases of fruit development in selected Rubiaceae (Gentianales).

PremiseThe Rubiaceae are ideal for studying the diversity of fruits that develop from flowers with inferior ovary. We aimed to identify morpho‐anatomical changes during fruit development that distinguish those derived from the carpel versus the extra‐carpellary tissues. In addition, we present the fruit genetic core regulatory network in selected Rubiaceae species and compare it in terms of copy number and expression patterns to model core eudicots in the Brassicaceae and the Solanaceae.MethodsWe used light microscopy to follow morphoanatomical changes in four selected species with different fruit types. We generated reference transcriptomes for seven selected Rubiaceae species and isolated homologs of major transcription factors involved in fruit development histogenesis, assessed their homology, identified conserved and new protein motifs, and evaluated their expression in three species with different fruit types.ResultsOur studies revealed ovary‐derived pericarp tissues versus floral‐cup‐derived epicarp tissues. Gene evolution analyses of FRUITFULL, SHATTERPROOF, ALCATRAZ, INDEHISCENT and REPLUMLESS homologs suggest that the gene complement in Rubiaceae is simpler compared to that in Brassicaceae or Solanaceae. Expression patterns of targeted genes vary in response to the fruit type and the developmental stage evaluated.ConclusionsMorphologically similar fruits can have different anatomies as a result of convergent tissues developed from the epicarps covering the anatomical changes from the pericarps. Expression analyses suggest that the fruit patterning regulatory network established in model core eudicots cannot be extrapolated to asterids with inferior ovaries.

Morpho-anatomical changes and antioxidant enzyme activity during the acclimatization of Genipa americana

Morpho-anatomical changes and antioxidant enzyme activity during the acclimatization of Genipa americana

Relationship between salicylic acid and resistance to mite in strawberry

Abstract The two-spotted spider mite (TSSM) Tetranychus urticae is a polyphagous pest which infests several wild and cultivated species of plants worldwide. To date, this mite is the most deleterious pest attacking the strawberry plant under a protected environment. Exogenously applied salicylic acid (SA) has been found to induce resistance to biotic and abiotic stresses. Morpho-anatomical changes in strawberry leaflets and TSSM preference tests were investigated in response to SA treatment. Plants grown in a greenhouse were foliar sprayed with different concentrations of SA (0 mg · L−1, 25 mg · L−1, 50 mg · L−1, 75 mg · L−1 and 100 mg · L−1). After the third application, certain parameters including the number of glandular and non-glandular trichomes, thickness of leaflet, abaxial cell wall, adaxial cell wall, palisade and lacunous parenchyma and mesophyll were measured using scanning electronic microscopy (SEM). Two-choice and non-choice assays were employed to verify the TSSM preference. Exogenous treatment with SA promoted morpho-anatomical changes in the following parameters, namely: thickness of the leaflets, mesophyll, lacunous and palisade parenchyma, cell wall (abaxial and adaxial) and the number of glandular and non-glandular trichomes in strawberry leaflets. In general, TSSM preferred less leaflets treated with SA compared with the control in a two-choice assay. A lesser number of TSSM eggs and live females were also recorded in leaflets treated with SA compared with the control plants in no-choice assays. The values of the number of eggs and live females correlated negatively with those obtained for the morpho-anatomical traits induced by exogenous SA.

Developmental plasticity in Arabidopsis thaliana under combined cold and water deficit stresses during flowering stage.

Morpho-physiological changes were observed in Arabidopsis plants acclimated to long-term combined cold and water deficit stresses. Limiting growth and differences in bolting, flowering, and silique development were evidenced. In nature, plants are exposed to multiple and simultaneous abiotic stresses that influence their growth, development, and reproduction. In the last years, the study of combined stresses has aroused the interest to know the physiological and molecular responses, because these new stress conditions are probed to be different from the sum of the individual stress. We are interested in the study of the acclimation of plants growing under the combination of cold and water deficit stresses prevalent in cold-arid or semi-arid climates worldwide. We hypothesized that the reproduction of the acclimated plants will be compromised and affected. Arabidopsis plants were submitted to long-term combined stress from the beginning to the reproductive stage, when floral bud was visible, until the silique development. Our results demonstrate severe morpho-anatomical changes after acclimation to combined stress. Inflorescence stem morphology was altered having a delayed bolting and a limited growth. Flowering and silique formation were delayed, and a higher size in the corolla and the petals was observed. Flower and silique number were severely diminished as a result of combined stress, unlike acclimated plants to individual cold stress. These traits were recovered after deacclimation to optimal conditions and plants achieved similar silique production as control plants. The long-term stress results suggest that there is not a single dominant stress, but there is an alternating dominance depending on the structure or the plant stage development evaluated.

Micro-morphological response of some native dicotyledonous species to particulate pollutants emitted from stone crushing activities.

Stone crushing processes release particulates and associated noxious substances in our surroundings that are continuously destructing environmental conditions and ecosystem health. Morpho-anatomical changes in some medicinally important native species (Aerva javanica, Calotropis procera, Digera muricata, Euphorbia prostrata, Euploca strigosa, and Peganum harmala) exposed to heavy dust pollution were evaluated. These species selected on the basis of their ubiquitous distribution in the area. Two sites were selected in the Kirana Hills, Sargodha, one near stone crushers within 500-m radius (polluted) and the other 4km away from the crushers (control) varying significantly in amount of dust particles received. A decrease in plant height of all species from dust-polluted sites was observed. Reduction in height was more prominent in species like C. procera and D. muricata. Stem sclerification increased in C. procera and E. prostrata from the polluted site that is an indication of better tolerance to dust pollution. C. procera showed increased stem and leaf epidermis, stem sclerenchyma, and stem vascular bundles, which can increase resistance to dust pollution. E. strigosa was the most sensitive species in which all morpho-anatomical factors decreased. Survival of plant species depended on specific structural modifications in dermal, mechanical, parenchymatous, and vascular tissue. Overall, dust pollution severely affected plant morphological and micro-morphological traits, but the response of selected species to dust pollution was variable. It is concluded that stem and leaf anatomical traits like size of dermal and storage tissue thickness and stomatal density are good indicators for biomonitoring of dust pollution.

Weathering deterioration in pre-harvest of soybean seeds: physiological, physical, and morpho-anatomical changes

ABSTRACT: Successive cycles of water absorption and loss favor weathering deterioration, one of the main factors that affect the quality of soybean seeds. This study evaluated the physiological, physical, and morpho-anatomical changes in soybean seeds under weathering deterioration at the pre-harvest phase. Six soybean cultivars (BMX Apolo, DM 6563, NS 5959, NA 5909, BMX Potencia, and TMG 1175) were produced in a greenhouse and underwent weathering deterioration through a rainfall simulation system, applying 0, 60, 120, and 180 mm of precipitation at pre-harvest phase. Each rainfall level was divided into two applications at an interval of 72 h: 60 mm (30 + 30), 120 mm (60 + 60), and 180 mm (90 + 90). After harvest, the seeds were evaluated for germination, vigor, physical and morpho-anatomical properties. Weathering deterioration induced by simulated rainfall at the pre-harvest phase contributes to the reduction in soybean seed germination and vigor and is conditioned by the soybean genotype. The increase in intensity of simulated rainfall led to a more significant weathering damage in seeds, as evidenced by the X-ray and tetrazolium test. Cultivars DM 6563 and BMX Potencia were more susceptible, while NA 5909 was less susceptible to weathering deterioration (especially at the highest level; 120 mm and 180 mm). Anatomical changes caused by weathering deterioration lead to cell compaction and rupture, mainly in the cell layers of the hourglass and parenchyma, forming intracellular spaces. The presence of weathering damage caused a reduction in physiological soybean seed quality.

Boron lack affects the anatomy of leaf, stem and root of cherry tomato

Boron is one of the most limiting micronutrients to the good development and production of tomato, and the damage intensity varies with the cultivars, their phenological stages and the environmental conditions. The aim of this work was to evaluate the effects of boron concentrations in nutrient solution on agronomic performance and possible morpho-anatomical changes in leaves, stems, roots and fruit production of the cherry tomato cultivated in a hydroponic system. The experiment consisted of four concentrations of boron (1.0; 10.0; 25.0; and 50.0 μmol L−1) and plants evaluation at different phenological stages: 43, 53, 66 and 84 days after sowing. The concentration of 1 μmol L−1 boron in nutrient solution caused the greatest limitation to the growth and development of the tomato, from the vegetative stage, with aggravation of damage in the subsequent stages. The anatomical alterations in the leaf, stem and root tissues became more conspicuous with the advancement of the phenological stages, preventing fruit production. The estimated dose of 35 μmol L−1 boron results in the best growth and production of the tomato ‘Iracema.’

Visible-light reduced silver nanoparticles’ toxicity in Allium cepa test system

Silver nanoparticles (AgNPs) are widely used in consumer products due to their antibacterial property; however, their potential toxicity and release into the environment raises concern. Based on the limited understanding of AgNPs aggregation behavior, this study aimed to investigate the toxicity of uncoated (uc-AgNP) and coated with polyvinylpyrrolidone (PVP-AgNP), at low concentrations (0.5–100 ng/mL), under dark and visible-light exposure, using a plant test system. We exposed Allium cepa seeds to both types of AgNPs for 4–5 days to evaluate several toxicity endpoints. AgNPs did not cause acute toxicity (i.e., inhibition of seed germination and root development), but caused genotoxicity and biochemical alterations in oxidative stress parameters (lipid peroxidation) and activities of antioxidant enzymes (superoxide dismutase and catalase) in light and dark conditions. However, the light exposure decreased the rate of chromosomal aberration and micronuclei up to 5.60x in uc-AgNP and 2.01x in PVP-AgNP, and 2.69x in uc-AgNP and 3.70x in PVP-AgNP, respectively. Thus, light exposure reduced the overall genotoxicity of these AgNPs. In addition, mitotic index alterations and morphoanatomical changes in meristematic cells were observed only in the dark condition at the highest concentrations, demonstrating that light also reduces AgNPs cytotoxicity. The light-dependent aggregation of AgNPs may have reduced toxicity by reducing the uptake of these NPs by the cells. Our findings demonstrate that AgNPs can be genotoxic, cytotoxic and induce morphoanatomical and biochemical changes in A. cepa roots even at low concentrations, and that visible-light alters their aggregation state, and decreases their toxicity. We suggest that visible light can be an alternative treatment to remediate AgNP residues, minimizing their toxicity and environmental risks.

Thyroid Hormone Signalling: From the Dawn of Life to the Bedside.

Thyroid hormone (TH) signalling is a key modulator of fundamental biological processes that has been evolutionarily conserved in both vertebrate and invertebrate species. TH may have initially emerged as a nutrient signal to convey environmental information to organisms to induce morpho-anatomical changes that could maximise the exploitation of environmental resources, and eventually integrated into the machinery of gene regulation and energy production to become a key regulator of development and metabolism. As such, TH signalling is particularly sensitive to environmental stimuli, and its alterations result in fundamental changes in homeostasis and physiology. Stressful stimuli of various origins lead to changes in the TH-TH receptor (TR) axis in different adult mammalian organs that are associated with phenotypical changes in terminally differentiated cells, the reactivation of foetal development programmes, structural remodelling and pathological growth. Here, we discuss the evolution of TH signalling, review evolutionarily conserved functions of THs in essential biological processes, such as metamorphosis and perinatal development, and analyse the role of TH signalling in the phenotypical and morphological changes that occur after injury, repair and regeneration in adult mammalian organs. Finally, we examine the potential of TH treatment as a therapeutic strategy for improving organ structure and functions following injury.

Pollen development at high temperature and role of carbon and nitrogen metabolites.

Fruit and seed crop production heavily relies on successful stigma pollination, pollen tube growth, and fertilization of female gametes. These processes depend on production of viable pollen grains, a process sensitive to high-temperature stress. Therefore, rising global temperatures threaten worldwide crop production. Close observation of plant development shows that high-temperature stress causes morpho-anatomical changes in male reproductive tissues that contribute to reproductive failure. These changes include early tapetum degradation, anther indehiscence, and deformity of pollen grains, all of which are contributing factors to pollen fertility. At the molecular level, reactive oxygen species (ROS) accumulate when plants are subjected to high temperatures. ROS is a signalling molecule that can be beneficial or detrimental for plant cells depending on its balance with the endogenous cellular antioxidant system. Many metabolites have been linked with ROS over the years acting as direct scavengers or molecular stabilizers that promote antioxidant enzyme activity. This review highlights recent advances in research on anther and pollen development and how these might explain the aberrations seen during high-temperature stress; recent work on the role of nitrogen and carbon metabolites in anther and pollen development is discussed including their potential role at high temperature.