Histomorphological, Histochemical and Ultrastructural Studies on the Healthy Liver of Yemen Veiled Chameleon (Chamaeleo calyptratus) in Southern Saudi Arabia / Estudios Histomorfológicos, Histoquímicos y Ultraestructurales en el Hígado Sano del Camaleón Velado de Yemen (Chamaeleo calyptratus) en el Sur de Arabia Saudita

SUMMARY: The livers of reptiles are being studied as a model for the link between the environment and hepatic tissue. There have been few investigations on the histology of reptile livers, and very few or no studies have examined the histology of liver of veiled chameleon (Chamaeleo calyptratus). This paper describes the histomorphological, histochemical and ultrastructural characterization of the liver of veiled chameleons in southern Saudi Arabia. Seven Chamaeleo calyptratus were captured in the summer season in Abha City, Aseer region, southern Saudi Arabia. Chamaeleon liver samples were processed for histomorphology, histochemistry and ultrastructure analyses. Morphologically liver of Chamaeleo calyptratus was observed as a large dark brown organ with lighter speckles, which represent melanin deposits. It located at the ventral part of abdominal cavity forward of the stomach. Its dimensions approximately were 3.7 x 2 cm. The liver was a bilobed organ divided into two lobes, right and left lobes. The right one was bigger than the others. The gallbladder was well developed and had an elongated shape, situated between the two lobes and contained the bile for the digestion. Microscopically, the liver was found to be covered by a thick layer of connective tissue, which formed the hepatic capsule. Hepatic parenchyma probably appeared in cross sections as hepatic glandular-like alveoli "acini" or follicular structures with various diameters, each acinus contains approximately four to six hepatocytes, surrounded by sinusoidal capillaries filled with abundant melanomacrophages, which are absent in birds and mammals. Melanomacrophages are common in the hepatic parenchyma's perisinusoidal areas, particularly near portal spaces. Hepatocytes are polyhedral or pyramidal with and mostly contained large, rounded nuclei mostly peripherally located, with prominent dark oval nucleoli. Some of nuclei are eccentric or central position. The cytoplasm appeared spongy or vacuolated and more eosinophilic when stained by hematoxylin-eosin and strongly reactive to PAS staining technique, indicating abundant glycogen content. The reticular fibers that surround hepatocytes, blood arteries, and sinusoids supported the hepatic parenchyma. The blood sinusoids are seen interspersed among hepatocytes of varying sizes. The sinusoidal lumen was bordered by flattened endothelial cells and includes elliptical nucleated erythrocytes and liver macrophages as phagocytes, which are also known as Kupffer cells. Branches of the portal vein, hepatic artery, small bile duct, and lymph vessels were detected in the hepatic portal area "tract" or triad which made up of connective. Hematopoietic tissue was observed in subcapsular region and portal triads. Ultrastructurally, the hepatocyte appeared polyhedric containing a single large rounded basal or eccentric vesicular nucleus with prominent nucleolus. Extensive network of rough endoplasmic reticulum (RER) often arranged in an array parallel to the nuclear membrane with many mitochondria, and Golgi apparatus were described. The cytoplasm contained glycogen granules, vesicles or vacuoles scattered throughout the cytoplasm especially at the apical region were reported. The bile canaliculi and the hepatic "Kupffer" cells were also discussed. This is the first study on the histological characterization of the healthy liver of Yemen veiled chameleon in southern Saudi Arabia. The findings reported here should be used as a reference to compare with the pathological abnormalities of the liver in this animal.

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Biochemical and insecticidal efficacy of clove and basil essential oils and two photosensitizers and their combinations on Aphis gossypii glover (Hemiptera: Aphididae)

The present study investigates the insecticidal and biochemical effects of two essential oils (EOs) and two photosensitizers against cotton aphids in a laboratory setting. The EOs evaluated were clove (Syzygium aromaticum L.) and basil (Ocimum basilicum), while the photosensitizers were rose bengal and rhodamine B. The individual median lethal concentrations (LC50) revealed that clove was ~4.44 times more potent than basil, and rhodamine B was ~1.34 times more potent than rose bengal. The mortality rates increased using higher concentrations of the photosensitizers and prolonging exposure time to sunlight. The most effective combination against adult aphids was found to be a mixture of sub-lethal concentrations of clove and rhodamine B, resulting in a mortality rate of 92.31%. Conversely, the combination of basil and rose bengal exhibited the lowest efficacy with a mortality rate of 33.33%. Biochemical analyses indicate that Rhodamine B, basil, and the basil-rhodamine B mixture (mixture C) significantly reduced trehalase activity. However, the protease activity significantly increased in aphids treated with rose bengal, clove, and the clove-rose bengal mixtures (mixtures A and B). The lipase activity is notably decreased upon treatment with rhodamine B and clove. Glutathione S-transferase (GST) activity decreased in aphids treated with rose bengal and the basil-rhodamine B mixtures (mixtures C and D), suggesting that GST did not play a role in detoxifying these compounds, thereby explaining the susceptibility of A. gossypii. Overall, the combination of essential oils and photosensitizers has demonstrated a synergistic effect in controlling Aphis gossypii, offering great potential as an effective strategy for aphid management.