Retinal characterization in the eyes of two bats endemic in the Egyptian fauna, the Egyptian fruit bat (Rousettus aegyptiacus) and insectivorous bat (Pipistrellus kuhlii), using the light microscope and transmission electron microscope

Ultrastructural and SEM-EDX Analysis Characterizations of the Pecten Oculi of the Eurasian Stone-Curlew (Burhinus oedicnemus): New Insights to Its Migratory Adaptations With Northern Egyptian Coast

Our study represents the first attempts to describe the ultrastructure features in addition to SEM-EDX analysis of the pecten oculi of the nocturnal, visually active Eurasian stone-curlew. The present study was carried out on 10 normal pecten oculi from the migrant Eurasian stone-curlew (Burhinus oedicnemus) that was captured from the Northern Egyptian coast, Edku Lake, Edku, Behera, Egypt. The intraocular folded quadrilateral fan black pecten oculi was observed on the posteroinferior wall of the eyeball. The pecten oculi had 18-20 pleats, with narrow spaces in-between. Our SEM findings showed a tortuous, coiled pecteneal surface due to numerous blood capillaries. The apical part was oriented toward the ciliary body, but the basal part was derived from the retina, just behind the optic nerve. The outer pleat surfaces are covered by the vitreopecteneal limiting membrane, which carries numerous hyalocyte cells on the outer pleat surface. The transverse sections revealed numerous blood capillaries surrounded by numerous melanin granules. Each basal part was surrounded by a thin, elevated ridge. Our SEM-EDX analysis revealed that carbon is the highest (half percent), oxygen represents about one-third, and nitrogen is one-fifth percent of all elements. The lowest elements are sulfate at the apical part and phosphorus in the middle and basal parts. In conclusion, our findings reveal that the number of pecteneal pleats is related to the nocturnal active visual pattern and the lifestyle of this migratory bird.

Antagonism of rhizosphere Trichoderma brevicompactum DTN19 against the pathogenic fungi causing corm rot in saffron (Crocus sativus L.) in vitro

Introduction

Corm rot in saffron (Crocus sativus L.) significantly impacts yield and quality. Non-toxic fungi, particularly Trichoderma species, are valuable for biological control due to their production of diverse and biologically active secondary metabolites.

Methods

This study aimed to isolate an effective antagonistic fungus against the pathogenic fungi causing corm rot in saffron. Four pathogenic fungi (Fusarium oxysporum, Fusarium solani, Penicillium citreosulfuratum, and Penicillium citrinum) were isolated from diseased saffron bulbs in Chongming. Initial screening through dual culture with these pathogens re-screening from rhizosphere soil samples of C. sativus based on its inhibitory effects through volatile, nonvolatile, and fermentation broth metabolites. The inhibitory effect of biocontrol fungi on pathogenic fungi in vitro was evaluated by morphological observation and molecular biology methods.

Results

Antagonistic fungi were identified as Trichoderma brevicompactum DTN19. F. oxysporum was identified as the most severe pathogen. SEM (scanning electron microscope) and TEM (transmission electron microscope) observations revealed that T. brevicompactum DTN19 significantly inhibited the growth and development of F. oxysporum mycelium, disrupting its physiological structure and spore formation. Additionally, T. brevicompactum DTN19 demonstrated nitrogen fixation and production of cellulase, IAA (Indole acetic acid), and siderophores. Whole-genome sequencing of strain DTN19 revealed genes encoding protease, cellulase, chitinase, β-glucosidase, siderophore, nitrogen cycle, and sulfate transporter-related proteins.

Discussion

T. brevicompactum DTN19 may inhibit the propagation of pathogenic fungi by destroying their cell walls or producing antibiotics. It can also produce IAA and iron carriers, which have the potential to promote plant growth. Overall, T. brevicompactum DTN19 showed the development prospect of biological agents.

Comparative study of the ciliary body and iris morphology in the anterior eye chamber of five different vertebrate classes

One crucial component of the optical system is the ciliary body (CB). This body secretes the aqueous humour, which is essential to maintain the internal eye pressure as well as the clearness of the lens and cornea. The histological study was designed to provide the morphological differences of CB and iris in the anterior eye chambers of the following vertebrate classes: fish (grass carp), amphibians (Arabian toad), reptiles (semiaquatic turtle, fan-footed gecko, ocellated skink, Egyptian spiny-tailed lizard, Arabian horned viper), birds (common pigeon, common quail, common kestrel), and mammals (BALB/c mouse, rabbit, golden hamster, desert hedgehog, lesser Egyptian jerboa, Egyptian fruit bat). The results showed distinct morphological appearances of the CB and iris in each species, ranging from fish to mammals. The present comparative study concluded that the morphological structure of the CB and iris is the adaptation of species to either their lifestyle or survival in specific habitats.

Pecten oculi of kestrel (Falco tinnunculus rupicolaeformes) and little owl (Athene noctua glaux): Scanning electron microscopy and histology with unique insights into SEM-EDX elemental analysis

There is scanty data about the comparative morphological features between the pecten oculi of two carnivorous birds with different visual active clock hours: the diurnal common kestrel and the nocturnal little owl. This study illustrated the comparative gross, scanning electron microscopy, and histological characteristics between pecten oculi of kestrel and little owl. This study first attempts to describe the scanning electron microscopy-energy dispersive x-ray (SEM-EDX) elemental analysis at the parts (apex, middle, and base) of the pecten oculi of these two birds. The present study results observed the same position, origin, directions, parts, convoluted outer pleat surfaces, and SEM-EDX elemental analysis, but there were some minor variations due to the different visual active clock hours. These minor variations were summarized in the following points: pleat number (21-23 in the kestrel and 10-11 in the owl), shape (fan rhomboid in the kestrel and accordion in the owl), inter-pleat spaces (wider in the kestrel than in the owl), pigmentations (highly black pigmented in the owl than in the kestrel), hyalocyte cell aggregations (highest in the middle and dwindling at the apex and base in the kestrel, while highest in the middle and base and dwindling at the apex in the owl), and SEM-EDX elemental analysis percentage. SEM/EDX elemental analysis confirmed the presence of oxygen (the highest one), carbon, nitrogen (the second one), nitrogen (the third one), and aluminum (the lowest one) in varying percentages within the pecten oculi; these findings contribute to our understanding of its structural, adaptations with different visual active clock hours, and functional characteristics. RESEARCH HIGHLIGHTS: This study compared the pecten oculi of two carnivorous birds with different visual active clock hours: the diurnal common kestrel and the nocturnal little owl. Anatomically, the characteristic features were similar in both the birds, but some minor variations were observed adapted to their visual active clock hours. The pecten oculi of both birds were analyzed using SEM-EDX for elemental analysis, and it revealed that oxygen was the highest elemental concentration, followed by carbon and nitrogen. Aluminum concentrations were small as per SEM-EDX analysis. The study suggested that the pecten oculi of these birds are related to their active visual clocks and adaptive nutritional mechanisms.

Antagonism of Rhizosphere Streptomyces yangpuensis CM253 against the Pathogenic Fungi Causing Corm Rot in Saffron (Crocus sativus L.)

Plant diseases lead to a significant decline in the output and quality of Chinese herbal medicines. Actinomycetes play a vital role in the rhizosphere ecosystem. This is especially true for Streptomyces, which have become a valuable biological control resource because of their advantages in producing various secondary metabolites with novel structures and remarkable biological activities. The purpose of this study was to isolate an effective antagonistic actinomycete against the pathogen of corm rot in saffron. An antagonistic actinomycete, CM253, was screened from the rhizosphere soil samples of Crocus sativus, by plate co-culture with four pathogenic fungi (Fusarium oxysporum, Fusarium solani, Penicillium citreosulfuratum, and Penicillium citrinum). CM253 inhibited the growth and development of F. oxysporum hyphae by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, by analyzing the degrading enzyme, the growth-promoting performance, and the whole genome of strain CM253, it was identified as Streptomyces yangpuensis, which produces NH3, protease, glucanase, cellulase, IAA, and ACC deaminase. In addition, 24 secondary metabolite synthesis gene clusters were predicted in antiSMASH. We identified genes encoding 2,3-butanediol; methionine; isoprene (metH, mmuM, ispEFH, gcpE, idi, and ilvABCDEH); biofilm formation; and colonization (upp, rfbBC, efp, aftA, pssA, pilD, fliA, and dhaM). Above all, S. yangpuensis CM253 showed the potential for future development as a biocontrol agent.

Biological features of the pecten oculi of the European wild quail (Coturnix coturnix): Adaptative habits to Northern Egyptian coast with novel vision to its SEM-EDX analysis

The present investigation was prepared to give a complete ultrastructural characterization of the pecten oculi of the diurnal European wild Quail to describe their adaptation habits to the Northern Egyptian coast. Our work declares the first endeavor is the elemental analysis using scanning electron microscopy-energy dispersive X-ray (SEM-EDX) to show the migration effect on their eye. The intra-ocular quadrilateral trapezoid black pigmented plicated type pecten oculi were observed on the postero-inferior wall of the eyeball with craniocaudal and posterio-anterior directions along the fetal fissure. The pecten oculi consist of three parts: the basal, body, and apical. The basal part originated behind the optic nerve, forming the slightly elevated border, while the apical part was directed toward the ciliary body. There are 10-11 pleats with interpleat space. The coiled surface refers to numerous capillary vessels. The smooth head of each pleat was kidney-like, strongly attached to a bridge. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. There are numerous melanosomes and little hyalocytes on the pecteneal pleat's outer surfaces. The thick basal part of each pleat had numerous thick longitudinal microfolds that refer to the numerous blood capillaries attached to the retina as supporting roots. SEM/EDX elemental analysis revealed that carbon is the highest element (half), while oxygen represents about one-third. In the meantime, the lowest element is the phosphate at the apical part, while the lowest element in the rest is the sulfate. Finally, the pecten oculi are thought to be a reflection of the avian lifestyle and ecological adaptations. HIGHLIGHTS: Our work is the first description of the elemental analysis using SEM-EDX to show the migration effect on their eye. The quadrilateral trapezoid black pigmented plicated type pecten oculi were observed on the postero-inferior wall of the eyeball with cranio-caudal and posterio-anterior directions along the fetal fissure. The basal part of the pecten oculi originated behind the optic nerve, forming the slightly elevated border, while the apical part was directed toward the ciliary body. There are 10-11 pleats with interpleat space. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. There are numerous melanosomes and little hyalocytes on the pecteneal pleat's outer surfaces. SEM/EDX elemental analysis revealed that carbon is the highest element (half percent), while oxygen represents about one-third of the element's percent meanwhile, the lowest element is phosphate at the apical part, while the lowest element in the rest is the sulfate.

Gross, ultrastructural, and histological characterizations of pecten oculi of the glossy ibis (Plegadis falcinellus): New insights into its scanning electron microscope-energy dispersive X-ray analysis

The current study shows the first attempts to clarify the gross, ultrastructure, and histological properties of the pecten oculi of the diurnal, visually active glossy ibis, as well as scanning electron microscope-energy dispersive X-ray (SEM-EDX) image analysis (Plegadis falcinellus). The pecten oculi was found on the eyeball's posteroinferior wall, adjacent to the optic nerve in both the craniocaudal and posterio-anterior directions. The plicated quadrilateral black pigmented pecten oculi consisted of a base, 10-12 pleats, and an apex. The base was joined by an elevated ridge and derived from the non-vascular retina, while the apex was not a fused part and was found neighboring the gelatinous vitreous body. The limited interpleat spaces were somewhat wider at the base of the pecten oculi. The outer surface of each highly vascular pecten pleat revealed a tortious coiled formation due to the existence of a considerable number of capillary vessels. The outer pleat surfaces had a vitreopecteneal limiting membrane that segregated the pecten pleats from the vitreous body. The high SEM magnification revealed that there are considerable plentiful hyalocyte cells on the outer surface of the pleats. The SEM-EDX analysis of the elementary formatting of the pecten oculi (at apex, middle, and base) clarified that the carbon represents the highest and a half percent. Furthermore, oxygen represents one-third of all elemental composition in the three regions, while the lowest percentage is calcium. Finally, the pecten oculi characterizations of this migratory bird on the Northern Egyptian shore were associated with their adaptive dietary strategies.

The Opto-Respiratory Compromise: Balancing Oxygen Supply and Light Transmittance in the Retina

The light-absorbing retina has an exceptionally high oxygen demand, which imposes two conflicting needs: high rates of blood perfusion and an unobstructed light path devoid of blood vessels. This review discusses mechanisms and physiological trade-offs underlying retinal oxygen supply in vertebrates and examines how these physiological systems supported the evolution of vision.

Morphological adaptations on the eye of the golden gray mullet (Chelon aurata): Using light and scanning electron microscopical study

The present investigations were designed to describe the ultrastructural properties of the eye of the golden gray mullet (Chelon aurata). For this purpose, the eyes were examined grossly, and by light and electron microscope. The external layer consists of the cornea and the sclera. Three layers compose the cornea; the anterior stratified cuboidal epithelial; the anterior limiting (Bowman) membrane; and the thick dermal layer of the stroma. The mucoidal layer has small collagen fiber bundles embedded in the CT layer and located between the anterior portion of the scleral cornea and the dermal stroma, (or "substancia propria"). The iridescent layer is thin at the center and thick at the periphery. It contains a pigmented layer with many ossicles. SEM analysis reveals that the cornea consists of undetermined shaped cells joined together by numerous thread-like micro-ridges, with several micro-tubercles on the external surface. The photoreceptor layer had two types of cells: the rod-shaped and the cone-shaped cells. The cone cells differentiate into two types of cells: single and double cells. SEM analysis of the retina showed that rod cells appear as thin long uniform rod-like, while the cone cells appear as rod cells with ovoid bases. SEM analysis demonstrates that the inner side of the retinal epithelium appears to be wrapped around itself. The morphological appearance of the eye adapts to life in superficial aquatic conditions. In conclusion, the current findings provide morphologic evidence to better understand the mechanism of fish vision adaptation to environmental conditions. RESEARCH HIGHLIGHTS: The transparent cornea composed of three layers; anterior stratified cuboidal epithelial, Bowman's membrane, and a thick dermal stromal layer. The mucoidal layer is formed from small collagen fibers bundles embedded in the CT layer and located between the anterior portion of the scleral cornea and the dermal stroma. There are two types of photoreceptor cells: rod and cone cells. Cone cells can be single and double cells.

Snout cutis of the domestic pig (Sus scrofa domesticus, Linnaeus, 1758): Using light and transmission electron microscopy

The current study was designed to give microscopic view on the snout skin of the domestic pig (Sus scrofa domesticus) to clear its adaptations with the function of exploring for the food and pushing the objects. This study carried out on the snout skin of apparently healthy 1 year five pigs (Sus Scrofa) and examined under the light and transmission electron microscopy. Our results clarify that the snout skin cutis composed of the epidermis and the dermis. The epidermis consisted of stratum corneum, stratum granulosum, stratum spinosum, and stratum basale. The stratum corneum and the stratum spinosum appeared thicker than other parts. The dermis consisted of a reticular and a papillary dermis. For tightness junction between the dermis and the epidermis, the hemidesmosomes were observed, while the desmosomes were presented in abundant numbers at the level of stratum basale to ensure the adhesion between the keratinocytes. The merocrine sweat glands were observed in abundant numbers to provide the wetness of the snout to avoid its injury from friction during food exploring or pushing of the objects. We concluded that the adaptation of the snout skin with the environmental condition surrounding the studied domestic pig.