Light Regimes Research Articles

Basal Primatomorpha colonized Ellesmere Island (Arctic Canada) during the hyperthermal conditions of the early Eocene climatic optimum.

Anthropogenically induced warming is transforming Arctic ecosystems across a geologically short timescale, but earlier episodes of Earth history provide insights on the nature and limitations of biotic change in a rapidly warming Arctic. Late early Eocene strata (~52 Ma) of the Margaret Formation on Ellesmere Island, Nunavut, Canada sample a warm temperate ecosystem with a polar light regime situated at ~77°N paleolatitude. This extinct boreal ecosystem hosted a diversity of early Cenozoic vertebrates, including thermophilic taxa such as crocodilians and tapiroid perissodactyls. Here we describe two new species of the early primatomorphan Ignacius from Ellesmere, which are by far the northernmost known records for Paleogene Primatomorpha. Ellesmere species of Ignacius are sister taxa, indicating a single colonization of Ellesmere from farther south in North America coincident with the onset of the hyperthermal Early Eocene Climatic Optimum (EECO). The Ellesmere Ignacius clade differs from closely related taxa inhabiting mid-latitudes in being larger (thereby conforming to Bergmann's rule) and having modified dentition and muscles of mastication for a dietary regime emphasizing hard objects, possibly reflecting an increased reliance on fallback foods during long polar winters. The late early Eocene mammalian fauna of Ellesmere indicates that its unique paleoenvironment rendered it uninhabitable to some clades, including euprimates, while selected taxa were able to adapt to its challenging conditions and diversify.

Limited water stress modulates expression of circadian clock genes in Brachypodium distachyon roots

Organisms have evolved a circadian clock for the precise timing of their biological processes. Studies primarily on model dicots have shown the complexity of the inner timekeeper responsible for maintaining circadian oscillation in plants and have highlighted that circadian regulation is more than relevant to a wide range of biological processes, especially organ development and timing of flowering. Contribution of the circadian clock to overall plant fitness and yield has also long been known. Nevertheless, the organ- and species-specific functions of the circadian clock and its relation to stress adaptation have only recently been identified. Here we report transcriptional changes of core clock genes of the model monocot Brachypodium distachyon under three different light regimes (18:6 light:dark, 24:0 light and 0:24 dark) in response to mild drought stress in roots and green plant parts. Comparative monitoring of core clock gene expression in roots and green plant parts has shown that both phase and amplitude of expression in the roots of Brachypodium plants differ markedly from those in the green plant parts, even under well-watered conditions. Moreover, circadian clock genes responded to water depletion differently in root and shoot. These results suggest an organ-specific form and functions of the circadian clock in Brachypodium roots.

Effects of arborescent octocoral assemblages on the understory benthic communities of shallow Caribbean reefs

Since about 2000, octocorals on the shallow reefs of St. John, US Virgin Islands, have increased in abundance to form dense stands analogous to terrestrial forests. In this study, the ecology of octocoral forests was explored by testing for an effect of their canopies on the light regime and benthic invertebrate community in the understory habitat. Octocoral forests at five sites (7–13 m depth) were quantified on a spatial scale of meters by the height and density of octocoral colonies. Their effects on the understory habitat were evaluated through measurements of downwelling light, benthic invertebrate community structure, and the photophysiology (i.e., induction time) of the common coral, Porites astreoides (Lamarck, 1816). Octocoral forests composed of dense (> 5 octocorals m−2) and tall (mean height of 42 cm) octocoral colonies created an understory habitat characterized by flashes of bright light (i.e., sunflecking). Within the understory habitat at two of three study sites, the community structure of benthic invertebrates was modified by the octocoral canopy, but it remained unaffected at a third site. A test for the effects of sunflecking on the induction time of P. astreoides found no difference between colonies in the understory versus the open reef habitat. These results do not support the notion that the physiological phenotype of autotrophs in the understory habitat is modified to exploit sunflecking. The analysis of the benthic invertebrates in the understory habitat suggests that octocoral forests can change the community structure of this group of organisms, relative to the open reef. The causes of this change are unclear, but its absence at the most sheltered study site suggests that water motion may be a contributing factor. The strong likelihood that octocoral forests mediate ecologically significant changes in the community structure of invertebrates within their understory habitat warrants further investigation.

Advances in Photodynamic Therapy for the Treatment of Actinic Keratosis and Nonmelanoma Skin Cancer: A Narrative Review.

Photodynamic therapy (PDT) with photosensitization using 5-aminolevulinic acid (ALA) [including a nanoemulsion (BF-200 ALA)] is approved in the USA for the treatment of actinic keratoses (AKs); another derivative, methyl aminolevulinate, is not approved in the USA but is used in Europe. For AK treatment, the photosensitizer may be applied to individual AK lesions or, depending on treatment regimen, to broader areas of sun-damaged skin to manage field cancerization, although not all products are approved for field treatment. ALA-PDT and photosensitizers have also been used off-label for the treatment of nonmelanoma skin cancers, primarily basal cell carcinomas (BCCs) and cutaneous squamous cell carcinomas (cSCC). Advantages of PDT include potentially improved cosmesis and patient satisfaction; disadvantages include pain and duration of treatment. Alternative illumination approaches, including intense pulsed light as well as pulsed-dye lasers, have also been used successfully. Pretreating the affected tissue or warming during incubation can help to increase photosensitizer absorption and improve therapeutic efficacy. Combinations of multiple treatments are also under exploration. Reducing incubation time between photosensitizer application and illumination may significantly reduce pain scores without affecting treatment efficacy. Substituting daylight PDT for a conventional illumination source can also reduce pain without compromising efficacy. The objective of this narrative review is to describe current and ongoing research in the use of topical photosensitizers and modified light delivery regimens to achieve improved therapeutic outcomes with less toxicity in patients with AK, cSCC, BCC, and field cancerization.

Effect of Duration of LED Lighting on Growth, Photosynthesis and Respiration in Lettuce.

Parameters of illumination including the spectra, intensity, and photoperiod play an important role in the cultivation of plants under greenhouse conditions, especially for vegetables such as lettuce. We previously showed that illumination by a combination of red, blue, and white LEDs with a high red light intensity, was optimal for lettuce cultivation; however, the effect of the photoperiod on lettuce cultivation was not investigated. In the current work, we investigated the influence of photoperiod on production (total biomass and dry weight) and parameters of photosynthesis, respiration rate, and relative chlorophyll content in lettuce plants. A 16 h (light):8 h (dark) illumination regime was used as the control. In this work, we investigated the effect of photoperiod on total biomass and dry weight production in lettuce plants as well as on photosynthesis, respiration rate and chlorophyll content. A lighting regime 16:8 h (light:dark) was used as control. A shorter photoperiod (8 h) decreased total biomass and dry weight in lettuce, and this effect was related to the suppression of the linear electron flow caused by the decreasing content of chlorophylls and, therefore, light absorption. A longer photoperiod (24 h) increased the total biomass and dry weight, nevertheless an increase in photosynthetic processes, light absorption by leaves and chlorophyll content was not recorded, nor were differences in respiration rate, thus indicating that changes in photosynthesis and respiration are not necessary conditions for stimulating plant production. A simple model to predict plant production was also developed to address the question of whether increasing the duration of illumination stimulates plant production without inducing changes in photosynthesis and respiration. Our results indicate that increasing the duration of illumination can stimulate dry weight accumulation and that this effect can also be induced using the equal total light integrals for day (i.e., this stimulation can be also caused by increasing the light period while decreasing light intensity). Increasing the duration of illumination is therefore an effective approach to stimulating lettuce production under artificial lighting.

Experimental investigation of dynamic stall flow control using a microsecond-pulsed plasma actuator

To alleviate the performance deterioration caused by dynamic stall of a wind turbine airfoil, the flow control by a microsecond-pulsed dielectric barrier discharge (MP-DBD) actuator on the dynamic stall of a periodically pitching NACA0012 airfoil was investigated experimentally. Unsteady pressure measurements with high temporal accuracy were employed in this study, and the unsteady characteristics of the boundary layer were investigated by wavelet packet analysis and the moving root mean square method based on the acquired pressure. The experimental Mach number was 0.2, and the chord-based Reynolds number was 870 000. The dimensionless actuation frequencies F + were chosen to be 0.5, 1, 2, and 3, respectively. For the light dynamic regime, the MP-DBD plasma actuator plays the role of suppressing flow separation from the trial edge and accelerating the flow reattachment due to the high-momentum freestream flow being entrained into the boundary layer. Meanwhile, actuation effects were promoted with the increasing dimensionless actuation frequency F +. The control effects of the deep dynamic stall were to delay the onset and reduce the strength of the dynamic stall vortex due to the accumulating vorticity near the leading edge being removed by the induced coherent vortex structures. The laminar fluctuation and Kelvin–Helmholtz (K–H) instabilities of transition and relaminarization were also mitigated by the MP-DBD actuation, and the alleviated K-H rolls led to the delay of the transition onset and earlier laminar reattachment, which improved the hysteresis effect of the dynamic stall. For the controlled cases of F + = 2, and F + = 3, the laminar fluctuation was replaced by relatively low frequency band disturbances corresponding to the harmonic responses of the MP-DBD actuation frequency.

Bounds on boosted dark matter from direct detection: The role of energy-dependent cross sections

The recoil threshold of Direct Detection experiments limits the mass range of Dark Matter (DM) particles that can be detected, with most DD experiments being blind to sub-MeV DM particles. However, these light DM particles can be boosted to very high energies via collisions with energetic Cosmic Ray electrons. This allows Dark Matter particles to induce detectable recoil in the target of Direct Detection experiments. We derive constraints on scattering cross section of DM and electron, using XENONnT and Super-Kamiokande data. Vector and scalar mediators are considered, in the heavy and light regimes. We discuss the importance of including energy dependent cross sections (due to specific Lorentz structure of the vertex) in our analysis, and show that the bounds can be significantly different than the results obtained assuming constant energy-independent cross-section, often assumed in the literature for simplicity. Our bounds are also compared with other astrophysical and cosmological constraints.

Responses of photosystem to long-term light stress in a typically shade-tolerant species Panax notoginseng.

Photosynthetic adaptive strategies vary with the growth irradiance. The potential photosynthetic adaptive strategies of shade-tolerant species Panax notoginseng (Burkill) F. H. Chen to long-term high light and low light remains unclear. Photosynthetic performance, photosynthesis-related pigments, leaves anatomical characteristics and antioxidant enzyme activities were comparatively determined in P. notoginseng grown under different light regimes. The thickness of the upper epidermis, palisade tissue, and lower epidermis were declined with increasing growth irradiance. Low-light-grown leaves were declined in transpiration rate (Tr) and stomatal conductance (Cond), but intercellular CO2 concentration (C i) and net photosynthesis rate (P n) had opposite trends. The maximum photo-oxidation (P m) was greatly reduced in 29.8% full sunlight (FL) plants; The maximum quantum yield of photosystem II (F v/F m) in 0.2% FL plants was significantly lowest. Electron transport, thermal dissipation, and the effective quantum yield of PSI [Y(I)] and PSII [Y(II)] were declined in low-light-grown plants compared with high-light-grown P. notoginseng. The minimum value of non-regulated energy dissipation of PSII [Y(NO)] was recorded in 0.2% FL P. notoginseng. OJIP kinetic curve showed that relative variable fluorescence at J-phase (V J) and the ratio of variable fluorescent F K occupying the F J-F O amplitude (W k) were significantly increased in 0.2% FL plants. However, the increase in W k was lower than the increase in V J. In conclusion, PSI photoinhibition is the underlying sensitivity of the typically shade-tolerant species P. notoginseng to high light, and the photodamage to PSII acceptor side might cause the typically shade-tolerant plants to be unsuitable for long-term low light stress.

The nocturnal life of the great scallops (Pecten maximus, L.): First description of their natural daily valve opening cycle.

Valvometry techniques used to monitor bivalve gaping activity have elucidated numerous relationships with environmental fluctuations, along with biological rhythms ranging from sub-daily to seasonal. Thus, a precise understanding of the natural activity of bivalves (i.e., not exposed to stressful environmental variations) is necessary as a baseline for detecting abnormal behaviors (deviations). This knowledge is also needed to reliably interpret observations of bivalve gaping behavior and associated biological processes (e.g., respiration, nutrition) acquired over time-limited periods. With this in mind, we investigated the natural daily gaping activity of the great scallop (Pecten maximus) by continuously monitoring 35 individuals in several individual tanks and in situ (Bay of Saint-Brieuc, Brittany, France) using fully autonomous Hall effect sensors. Our results revealed a circadian cycle (τ = 24.0h) in scallop gaping activity. Despite significant inter-individual variability in mean opening and cycle amplitude, almost all individuals (87.5%) exhibited nocturnal activity, with valves more open at night than during the day. A shift in light regime in the tanks triggered an instantaneous change in opening pattern, indicating that light levels strongly determine scallop activity. Based on the opening status of scallops, we also identified several gaping behaviors deviating from the regular daily pattern (lack of rhythmicity, high daytime opening), potentially reflecting physiological weakness. While further long-term studies are required to fully understand the natural activity of scallops, these findings pave the way for studies focused on the scallop response to external factors and introduce further research into the detection of abnormal behaviors. Coupling observations of diel valve gaping cycles with other daily variations in organismal and environmental parameters could help explain mechanisms driving the growth patterns of scallops observed in their shell striations. From a technical perspective, our field-based monitoring demonstrates the suitability of autonomous valvometry sensors for studying mobile subtidal bivalve activity in remote offshore environments.

First Report of Strawberry Leaf Blight Caused by Fusarium Fujikuroi Species Complex in Bangladesh

Strawberry leaf blight is one of the devastating fungal diseases, responsible for reducing the quality of strawberry production worldwide. The present experiment was conducted to determine the pathogenic fungal association with strawberry leaves obtained from the experimental site of Botanical Garden, Jahangirnagar University, Bangladesh. A fungal pathogen causing leaf blight disease of the strawberry plant was detected as Fusarium fujikuroi species complex through classical and molecular approaches. Molecular characterization showed that nucleotide sequences of the internal transcribed region of the studied fungus (MH368119.1) were genetically identical with Fusarium fujikuroi species complex. Different culture media, pH, light regimes, temperatures were assayed to know the growth pattern of the identified pathogenic fungus. The optimum vegetative growth of Fusarium fujikuroi species complex was recorded on Potato Dextrose Agar, Potato Sucrose Agar, and Honey Peptone Agar media, at 25°C temperature, pH seven and under complete dark conditions. Among the three antagonistic fungi for the assessment as a biocontrol agent, Trichoderma asperellum was comparative effective against Fusarium fujikuroi species complex under in vitro conditions. Among systemic chemical fungicides, the highest mycelial inhibition (89.42%) of the isolated fungus was found by Tilt 250 EC (500 ppm). The leaf blight of strawberry caused by Fusarium fujikuroi species complex is the new record in Bangladesh. J Bio-Sci. 30(1): 11-20, 2022 (June)

Remote referencing strategy for high-resolution coded ptychographic imaging.

The applications of conventional ptychography are limited by its relatively low resolution and throughput in the visible light regime. The new development of coded ptychography (CP) has addressed these issues and achieved the highest numerical aperture for large-area optical imaging in a lensless configuration. A high-quality reconstruction of CP relies on precise tracking of the coded sensor's positional shifts. The coded layer on the sensor, however, prevents the use of cross correlation analysis for motion tracking. Here we derive and analyze the motion tracking model of CP. A novel, to the best of our knowledge, remote referencing scheme and its subsequent refinement pipeline are developed for blind image acquisition. By using this approach, we can suppress the correlation peak caused by the coded surface and recover the positional shifts with deep sub-pixel accuracy. In contrast with common positional refinement methods, the reported approach can be disentangled from the iterative phase retrieval process and is computationally efficient. It allows blind image acquisition without motion feedback from the scanning process. It also provides a robust and reliable solution for implementing ptychography with high imaging throughput. We validate this approach by performing high-resolution whole slide imaging of bio-specimens.

Phototherapy as a Treatment for Dermatological Diseases, Cancer, Aesthetic Dermatologic Conditions and Allergenic Rhinitis in Adult and Paediatric Medicine.

The development of light-emitting diodes (LEDs) has led to an increase in the use of lighting regimes within medicine particularly as a treatment for dermatological conditions. New devices have demonstrated significant results for the treatment of medical conditions, including mild-to-moderate acne vulgaris, wound healing, psoriasis, squamous cell carcinoma in situ (Bowen's disease), basal cell carcinoma, actinic keratosis, and cosmetic applications. The three wavelengths of light that have demonstrated several therapeutic applications are blue (415 nm), red (633 nm), and near-infrared (830 nm). This review shows their potential for treating dermatological conditions. Phototherapy has also been shown to be an effective treatment for allergenic rhinitis in children and adults. In a double-anonymized randomized study it was found that there was 70% improvement of clinical symptoms of allergic rhinitis after intranasal illumination by low-energy narrow-band phototherapy at a wavelength of 660 nm three times a day for 14 consecutive days. Improvement of oedema in many patients with an age range of 7-17 were also observed. These light treatments can now be self-administered by sufferers using devices such as the Allergy Reliever phototherapy device. The device emits visible light (mUV/VIS) and infra-red light (660 nm and 940 nm) wavelengths directly on to the skin in the nasal cavity for a 3 min period. Several phototherapy devices emitting a range of wavelengths have recently become available for use and which give good outcomes for some dermatological conditions.

Optical ptychography for biomedical imaging: recent progress and future directions [Invited

Ptychography is an enabling microscopy technique for both fundamental and applied sciences. In the past decade, it has become an indispensable imaging tool in most X-ray synchrotrons and national laboratories worldwide. However, ptychography's limited resolution and throughput in the visible light regime have prevented its wide adoption in biomedical research. Recent developments in this technique have resolved these issues and offer turnkey solutions for high-throughput optical imaging with minimum hardware modifications. The demonstrated imaging throughput is now greater than that of a high-end whole slide scanner. In this review, we discuss the basic principle of ptychography and summarize the main milestones of its development. Different ptychographic implementations are categorized into four groups based on their lensless/lens-based configurations and coded-illumination/coded-detection operations. We also highlight the related biomedical applications, including digital pathology, drug screening, urinalysis, blood analysis, cytometric analysis, rare cell screening, cell culture monitoring, cell and tissue imaging in 2D and 3D, polarimetric analysis, among others. Ptychography for high-throughput optical imaging, currently in its early stages, will continue to improve in performance and expand in its applications. We conclude this review article by pointing out several directions for its future development.

About thinning in the Arkhangelsk region

An analysis was made of the growth of birch-spruce plantations, passed through three stages of thinning (in 1966, 1974 and 1984) in the Northern district forestry (in the Obozersky forestry) in the Arkhangelsk region. The duration of observations is 54 years at the time of the last count in 2020. The results of past studies by employees of the FBU “SevNIILKh” were taken into account. During the period under review, the forest stand in the control section (without thinning) developed quite dynamically. The birch element of the forest prevailed at all stages of growth and was characterized by the highest productivity (I-II quality class) at the age of 40-50 years. At present, the period of active growth has already passed, the stands are approaching the age of natural ripeness, as evidenced by the decrease in the quality class to IV, the decrease in the average height, and the decrease in stock. Spruce in the second tier and in a depressed state. With the continuation of the decay of the birch element and with an increase in the light regime, the spruce will actively grow. The research data show that in stands that have been thinned, the trees become larger, the yield of large-sized marketable wood is greater than in nonsparse ones. Since the main place in the cost of timber belongs to quality indicators, the economic efficiency of plantations with thinning is obvious. Through thinning, it seems possible to form plantings of optimal composition and density, better growth rates and at the stage of main felling, providing a greater economic effect compared to control

Floristički diverzitet veštački podignutih sastojina različitih vrsta četinara na području Kosmaja (Srbija)

One of the causes of decrease of species diversity of forest ecosystems could be inadequate selection of tree species for afforestation and ameliorations. It is known that by establishing new forest ecosystem habitat conditions change, and thus, edaphic and hydrological conditions and light regime also change, which directly or indirectly reflects on plant species. The research included four artificially established stands (pure or mixed) in the area of Kosmaj, where various coniferous species were introduced in the process of substitution of autochthonous forests of Hungarian oak and Turkey oak. The largest total number of plant species was recorded in artificially established stand of common spruce, Atlas cedar, and Douglas-fir (41). The highest Shannon-Wiener diversity index was recorded in stand of Douglas-fir (3.22), and the lowest in pine stands (2.95-2.97). It was determined by cluster analysis that stand of Austrian pine and stand of Austrian pine and Scots pine have the largest degree of mutual floristic similarity.

ОСОБЕННОСТИ ЭКОЛОГИЧЕСКИХ ТРЕБОВАНИЙ ХЛОПЧАТНИКА К УСЛОВИЯМ ПРОИЗРАСТАНИЯ

Purpose: to determine the features of the ecological requirements of cotton to growth conditions. Discussion. To expand the area of cotton growing in Russia, it is necessary to solve the problems of acclimatization and zoning of cotton, since this crop has its own specific agro-requirements for growth conditions. The main factors influencing the development and productivity of a crop are temperature, moisture, light, soil, nutrient regime, and terrain. It has been determined that the minimum soil temperature at which cotton seeds germinate is 10–12 °C, the optimum air temperature for plant development is approximately 25–30 °C, but not higher than 36 °C, since cotton is depressed. It is drought tolerant but requires irrigation to increase yield. Cotton needs evenly diffused sunlight. The light regime is regulated by the seeding rate, the seeding method and the direction of rows. The best soils are loamy; heavy clay soils are suitable, but costly to improve water-physical properties; soils with a close occurrence of groundwater are of little use. Saline soils are suitable for chloride-sulfate salinization with a salt content of no more than 0.4 %, and for sodium sulfate – no more than 0.8 %. The content of exchangeable sodium in soil should not exceed 5 % of the total soil absorption complex. To form 1 ton of raw cotton, 50–60 kg of nitrogen, 10–15 kg of phosphorus, 50–60 kg of potassium and 50 kg of calcium are required. The flat surface is the most favorable for cotton cultivation. Conclusions. Knowledge of the ecological requirements for cotton will make it possible to assess the feasibility of cultivating this crop in a particular area.

Reef recovery and resilience: interpreting abiotic effects on critical early life stages of large brown algae

Rocky reefs throughout the temperate zone are dominated by large brown algae, which are major foundation species and ecosystem engineers. There is usually an ecological bottleneck at the early life stage of such algae when they are vulnerable to a wide range of stressors. A large earthquake that affected the coastline of southern New Zealand highlighted the combined effects of sudden changes to multiple stressors on large algal assemblages. In particular, the regime of temperature, sediment and light suddenly changed as the coastal platform was lifted, and sediments from the catchment occluded the light environment of nearshore waters. Here we tested the effects of these stressors on early survival and growth of 3 formerly dominant species—the fucoids Landsburgia quercifolia and Durvillaea antarctica and the laminarian Lessonia variegata—over 100 d using a culture laboratory. After 42 d, interactive effects were found for growth of all species. Decreasing light and increasing temperature had the greatest negative effect on L. variegata and D. antarctica growth. Growth was minimal at the lowest light treatment (PAR: 16 µmol m-2 s-1) for all species, but often least growth was found at the highest sediment treatment (PAR: 32 µmol m-2 s-1). L. quercifolia was resilient to increasing temperature, whereas survival and growth decreased with increasing temperature for D. antarctica and L. variegata. These results are highly suggestive of the coincident influences of major stressors on the post-earthquake marine ecosystem. These results also highlight that recovery of large brown algae following disturbance events is likely to be slow due to an increase in coastal sedimentation and extreme water temperature.

Microalgal biofilm behavior under light/dark cycles

Biofilm-based systems have attracted more attention recently as an alternative to the standard suspended-cells process for microalgae cultivation. It has also been shown that cells can be protected from photoinhibition under intense sunlight when submitted to alternately light and dark cycles. However, the biological response to light variation is not well understood. Therefore, in this work, a mechanistic model is developed based on Han's model to describe photosynthesis and respiration dynamics that cover different cycle times and a wide range of light fractions (Light/Dark fractions). Keeping the same average light intensity, increasing the light frequency enhances growth thanks to reduced photoinhibition. Increasing light fraction improves the growth rate as both the peak light intensity and the dark period decrease. Respiration variation in intermittent light regimes is for the first time considered in this model, giving a better explanation of biofilm growth experimental data. Understanding the model response will guide strategies for growth enhancement, and further optimize biofilm reactor design and operation and eventually benefit biomass productivity.

Different light programs affect the titer of vaccination of Newcastle in broiler chicken

Light is an important factor in the functioning of the body of birds, especially the immune system. Management of the lighting program in closed systems of poultry production, mainly by affecting the concentration of melatonin, can be operational on the effectiveness of vaccination. Newcastle disease can cause extensive damage to the poultry industry. Therefore, its timely diagnosis and assessment of the success of vaccination with methods such as the hemagglutination inhibition test are of particular importance. This study investigated the effect of two photoperiods on antibody titer against Newcastle virus following vaccination. Four groups of Ross broilers were examined for six weeks. Groups A and B received the live Newcastle vaccine twice, and groups C and D were not vaccinated against Newcastle. Groups A and C received a lighting program from the management handbook of Ross Broiler, and groups B and D received the continuous lighting program (23L:1D). During the breeding period, blood samples were taken six times from each group, and the HI test measured the antibody titer. The results showed that despite the higher antibody titer in group B compared to group A, this difference was not statistically significant (P>0.05). The feed conversion rate was higher in the groups that received the continuous photoperiod, and their mortality rate was lower than that of the other two groups. Comparing the results of the present study with those of various studies and articles shows the importance of the lighting regime in the success of vaccination.

Plasticity of Arabidopsis rosette transcriptomes and photosynthetic responses in dynamic light conditions.

With the high variability of natural growth environments, plants exhibit flexibility and resilience in regard to the strategies they employ to maintain overall fitness, including maximizing light use for photosynthesis, while simultaneously limiting light-associated damage. We measured distinct parameters of photosynthetic performance of Arabidopsis thaliana plants under dynamic light regimes. Plants were grown to maturity then subjected to the following 5-day (16 h light, 8h dark) regime: Day 1 at constant light (CL) intensity during light period, representative of a common lab growth condition; Day 2 under sinusoidal variation in light intensity (SL) during the light period that is representative of changes occurring during a clear sunny day; Day 3 under fluctuating light (FL) intensity during the light period that simulates sudden changes that might occur with the movements of clouds in and out of the view of the sun; Day 4, repeat of CL; and Day 5, repeat of FL. We also examined the global transcriptome profile in these growth conditions based on obtaining RNA-sequencing (RNA-seq) data for whole plant rosettes. Our transcriptomic analyses indicated downregulation of photosystem I (PSI) and II (PSII) associated genes, which were correlated with elevated levels of photoinhibition as indicated by measurements of nonphotochemical quenching (NPQ), energy-dependent quenching (qE), and inhibitory quenching (qI) under both SL and FL conditions. Furthermore, our transcriptomic results indicated downregulation of tetrapyrrole biosynthesis associated genes, coupled with reduced levels of chlorophyll under both SL and FL compared with CL, as well as downregulation of photorespiration-associated genes under SL. We also noticed an enrichment of the stress response gene ontology (GO) terms for genes differentially regulated under FL when compared with SL. Collectively, our phenotypic and transcriptome analyses serve as useful resources for probing the underlying molecular mechanisms associated with plant acclimation to rapid light intensity changes in the natural environment.