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Viviparity is an advanced reproducing process observed in certain bony fishes. Fish oocyte is protected by different coverings, the immediate one over oolemma being a non-cellular membrane known as Zona Radiata (ZR). ZR has shown variations in thickness, configuration and probably function at different fish oocyte and oocyte growth stages. In the present research work the ultrastructure of zona radiata around oocytes of guppy (Poecilia reticulata) has been studied by light and scanning electron microscopy methods concerning different oocyte growth stages. ZR was not observed at stages I and II. At stage III ZR was observed as a thin layer around the oocyte. It increased in thickness and complexity at stage IV (vitellogenesis) but showed different appearance and declined in thickness during the following stage. External surface characteristics, features of pore canals and probable function of ZR during oocyte development were also investigated.

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Impaired motor functions were reported in cholestatic animals. This disorder in the function and death of motor neurons is highly dependent on changes in the environment around astrocytes and the blood-brain barrier, which is moderated by the aquaporin 4 protein. For this reason, the effects of cholestasis on motor cortex histology and morphology and aquaporin 4 protein levels were investigated in this study. Samples were stained by hematoxylin-eosin method. Histological changes in cortical brain were investigated. The amount of AQP4 protein in control, sham, and experimental groups were tested by immunohistochemistry. The thickness of motor cortex in cholestatic samples increased in comparison with the control and sham groups. Also, cholestasis caused wrinkle chromatic nuclei. On the other hand, tissue necrosis was detected in cholestatic group compared with sham and control groups. Reduction of cells densities in some cortical layers has been observed, which is probably indicative of cholestasis-induced cell death. AQP4 expression significantly decreased in BDL (p <0.05), but not in other groups (P<0.05). In this study, the pathology of motor cortex, which has also been associated with the decrease of neurons, could be considered the cause of motion abnormalities and AQP4 level reduction in cholestatic rats.
 

 

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Atta Mouludi-Saleh¹, Soheil Eagderi¹, Keyvan Abbasi² & Manoochehr Nasri^3
1Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran; ²Inland Waters Aquaculture Research Center, Iranian Fisheries Sciences Research Institute, Agricultural Research, Education and Extension Organization, Bandar Anzali, Iran; ³Department of Fisheries Science and Engineering, Faculty of Agriculture and Natural Resources, Lorestan University, Khorramabad, Iran
Correspondent author: Soheil Eagderi, soheil.eagderi@ut.ac.ir
 
Abstract: Due to the presence of taxonomic ambiguity regarding Petroleuciscus ulanus and Alburnus atropatenae and the tendency to treat them as synonyms of each other, this study was conducted to validate these two species by comparing their morphometric and meristic characters in the Mahabad-Chai River, Urmia Lake basin. A total of 64 specimens of P. ulanus and 68 specimens of A. atropatenae were sampled and were then investigated for 17 morphometric and 7 meristic characters. Measurements were standardized to eliminate the effects of size due to allometric growth pattern, then their normality and abnormality were examined. Standardized data were analyzed using t-test, Mann-Whitney, principal component analysis (PCA) and discriminative function analysis based on P-value of Hotelling's t-test (DFA/Hotelling's T-test) methods. The results showed that the two species were significantly different in 11 morphometric and 2 meristic traits (P<0.05). DFA analysis also showed significance differences between the two studied species. Our results refute the synonymy hypothesis of Petroleuciscus ulanus and Alburnus atropatenae on the basis of morphometric and meristic traits. Therefore, based on the results of this study, the taxonomic identities of these two species are valid.
 

 

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Gambusia holbrooki Girard, 1859 is considered as one of the non-native and invasive species in the inland waters of Iran. This species occurs in most inland basins and aquatic bodies of Iran and has even been found in brackish waters. Extensive adaptations of this species to its different habitats caused numerous changes in its biological characteristics and morphological traits. The present study was performed to investigate the sexual dimorphism of G. holbrooki in the Gamasiab River, Kermanshah Province, Iran. 59 fish specimens were collected from the river in September 2017. After taxonomic confirmation and sex determination, 29 morphological traits were measured in fish samples using a caliper and their meristic traits were recorded. In total, 37 characters (including 8 meristic traits and 29 morphometric traits) were examined. After obtaining morphological data, Principal Component Analysis (PCA) and Discriminant Function Analysis (DFA) were utilized to compare morphological traits between male and female individuals. The results showed that the 59 specimens were comprised of 30 malea and 29 femalea. On the basis of the results, all morphological traits, except the caudal peduncle length, dorsal fin base length and a post-anal length, showed significant sexual dimorphism (p <0.05). The results of DFA and PCA analysis showed that males and females were completely different from each other in terms of morphometric traits. These findings indicate that there is a sexual dimorphism in G. holbrooki of the Gamasiab River. The sexual dimorphism observed in this fish species is due to the sexual selection and increase of reproductive success.