As the world’s second saltiest lake, Urmia Lake is the main source of halotolerant unicellular microalga, Dunaliella, in Iran. Recently, this lake and, consequently, its biodiversity are being threatened environmentally. Hence collecting, preserving, and identification of indigenous microorganisms of the lake are of great importance. The objective of the present study was the molecular screening of Dunaliella isolates in Urmia Lake. For this purpose, 32 samples were taken from different geographical regions of the lake. Then, their molecular pattern was examined based on 18S rDNA gene and intron-sizing method. Results based on conserved and species-specific primers of 18S rDNA illustrated that, depending on the various parts of the lake, the genetic variation of Dunaliella population differs. The amplified pattern for individual isolates was similar to that previously described for D. tertiolecta, D. bardawil and Dunaliella sp. ARIINW-M1/2. Also,18S rDNA sequencing and phylogenetic analysis of five index isolates showed that the isolates Dunaliella sp. ABRIINW-Ch5, -Sh6.3 and -U1/1 were grouped with different intron lacking species of Dunaliella, ABRIINW-Ch3.1 was clustered with Dunaliella sp. ABRIINW-M1/2, while the isolate Dunaliella sp. ABRIINW-S1.5 was clustered with intron-harboring species of D. bardawil, D. parva, and D. viridis. The results indicated that Urmia Lake is composed of isolates with different 18S rDNA profiles with various intron arrangement.

Strongyloides stercoralis is a prevalent parasite in some rural areas in the north of Iran. We decided to investigate whether the 18S ribosomal DNA sequence of the parasite in Iran is similar to the findings of the other re­searchers. We collected 3514 stool samples from Gilan and Mazandaran, northern Iran, during the year 2005-2006, from which 96 were found infected with S. stercoralis. Using Bearman method filariform larvae were isolated. The lar­val DNA was extracted and subjected for PCR amplification and sequencing. We found 2.73% S. stercoralis infection in stool examination. The partially sequence of Iranian S. stercoralis 18S rDNA gene was deposited to GenBank at accession number of EF062571. The 18S rDNA sequence of S. stercoralis in Iran is very similar to the related sequences deposited in GenBank (94-93% identification).

The genus Sarcocystis consists of intracellular coccidian protozoan parasites with the ability to invade muscle tissue and mature into sarcocysts, causing the zoonotic disease sarcocystosis. These parasites have an obligatory two-host life cycle, which correlates with prey-predator relationship. The distribution and prevalence of Sarcocystis in reptiles remains unclear, despite several previous reports. In this study, 54 faecal samples of various snake species and four faecal samples of several lizard species in Malaysia were examined for Sarcocystis through PCR amplification of the 18S rDNA sequence. Fourteen snake faecal samples were positive via PCR; however, only eight samples (14%) were found positive for Sarcocystis species, whereas four were positive for other genera and the identity of another three samples were unable to be determined. Further phylogenetic analysis of the 18S rDNA sequences revealed that the snakes were infected with either S. singaporensis, S. lacertae, or undefined Sarcocystis species which are closely related to either S. singaporensis or S. zuoi. Sarcocystis nesbitti infection was not identified in any of the infected snakes. This is the first report of identification of S. lacertae in the black-headed cat snake.

In this study, Dunaliella has been isolated in Jun. 2014 from Hoz-e Soltan and Aran-va Bidgol salt Lakes (Iran). The isolates have been identified morphologically with the aid of simple light and invert microscope after isolation and purification on their specific medium (Moh202). By using molecular techniques such as polymerase chain reaction (PCR) and amplification of 18S rDNA gene primers, further identification was done and morphological identification were confirmed. The isolation and molecular identification of the Dunaliella species from above-mentioned lakes revealed that, at least two species of Dunaliella, namely, D. parva and D. viridis exist in the studied area.

Dunaliella is a green halotolerant microalga, which has several industrial applications e.g. β-carotene production. Identification of different Dunaliella species has been carried out by morpho-physiological and recently molecular studies. To achieve an improved understanding of taxonomy, these studies are required to be in linkage. The present study describes molecular and specific morpho-physiological properties of a Dunaliella isolate obtained from Gavkhooni salt marsh in Iran. Phylogenetic analysis of Internal Transcribed Spacer region demonstrated that the isolate was associated with different species except D. salina (CCAP 19/18 and 19/30) and D.viridis. 18S rDNA size of the isolate was identical to that of D. tertiolecta and intron-lacking strains of D. salina. 18S rDNA fingerprint profile and phylogenetic analysis revealed D. tertiolecta as the closest taxon to the isolate. Features of optimum growth salinity (1.5-3% w/v) and maximum carotenoid per cell (0.7 pg cell-1) were comparable with reported data for D. terrtiolecta. Morphological characteristics including the size and color of the cells, presence and location of stigma and refractile granules were similar to those of D. tertiolecta. Totally, considering molecular and morpho-physiological properties, the isolate was attributed to the species D. tertiolecta and was named as Dunaliella tertiolecta ABRIINW-G3.

Phytoplanktons are organisms with a very high diversities and global distribution in different habitats. The high distribution of phytoplankton is due to ecological flexibility and their ability to tolerate different climatic conditions and environmental stress.Phytoplankton is the most sensitive biological indicators of water resources. The purpose of this study was to identify the phytoplankton species with emphasis on DNA bar-coding method. The study of phytoplankton variation and the identification of their species composition can provide useful information about the water quality. In this research project, a clone library of the ribosomal small subunit RNA gene (18S rDNA) in the nuclear genome was constructed by PCR using A and SSU-inR1 primers, and then, after examining the clones, selected clones were sequenced. Eleven analyzed sequences were identified correctly and characterized by a similarity search of the GenBank database using BLAST (NCBI). In this study, we revealed a wide range of taxonomic groups in the Alveolata (Ciliphora and Dinophyceae), Stramenopiles (Bacillariophyta and Bicosoecida), Rhodophyta and Haptophyceae. Moreover, we found species of fungi and Metazoa (Arthropoda). Most of the sequences were previously unknown but could still be assigned to important marine phyla. Clone library of 18S rDNA is an accurate method to identify marine specimens and it is recommended as an efficient method for phylogenic studies in marine environments. There seems to be a high diversity and abundance of small eukaryotes in the marine regions of Persian Gulf.

Proteases are the most important industrial enzymes. These enzymes have gained much attention due to their industrial applications in eliminating the environmental pollutions and improving the industrial processes. The aims of this research were the isolation and identification of native yeasts that were able to produce the alkaline protease. Several samples of soil, water and wastewater were collected from various places. The culture media used for screening of yeast spp. with potential of alkaline protease production were alkaline peptone agar and alkaline milk agar. The alkaline protease activity in potential spp. was measured using Lowry method. The effects of different culture media on the production of alkaline protease by selected yeast isolates were determined. For molecular identification of the best isolate, the DNA extraction was performed and the PCR followed using universal 18s rDNA primers. Among 27 isolates with the capability of alkaline protease production, one isolate with the most enzyme activity, 525 u/ ml, was selected for further processing. The best culture medium for alkaline protease production was YPG broth. The comparison of 18s rDNA sequence from isolated yeast with the highest enzyme activity, with the genomic database available in Gen Bank, using BLAST software showed that our yeast isolate had the highest similarity with Yarrowia lipolytica.Discussion and According to numerous applications of alkaline proteases industrially and the lack of their production in our country, the native strains could be beneficial for their production. Regarding to non-pathogenicity and high productivity of alkaline protease by our isolated yeast, Yarrowia lipolytica, this isolate could be introduced as an amenable strain for industrial production of alkaline protease.

Mollusca are one of the most diverse animal phyla whose phylogeny is considered as a controversial subject. Although some groups were traditionally classified as mollusca, they need to be identified again. High diversity of mollusca has created considerable taxonomic problems and despite their importance in marine biota, deep phylogenetic relationships of mollusca have scarcely been investigated. The aim of this study was to determine genetic diversity and differences between mollusca species in waters of Bandar Lengeh (Persian Gulf) of Iran. A clone library of the ribosomal small subunit RNA gene (18S rDNA) in the nuclear genome was constructed by PCR, and then, after examining the clones, selected clones were sequenced. The determined clone sequences were analyzed by a similarity search of the NCBI GenBank database using BLAST. Also, the fixation index (FST) factor was used in order to measure and understand the genetic differences between studied populations. In this study, seventeen sequences were identified belonging to two classes of Bivalvia and Gastropoda and they were used for phylogenetic analysis. According to the allele frequencies at each locus, FST value was significant in samples of Bandar Lengeh meaning that migration is in the lowest rate in the studied region. The present research project exhibited that clone library of 18S rDNA might be accounted as a beneficial tool to identify marine specimens and estimate the actual species diversity in marine environments. Moreover, these findings confirmed the effective role of molecular studies for the identification and taxonomy of speciesfrom the natural resources to obtain reliable data.

Myxosporeans are best known for the diseases they cause in commercially important fish species. Identification of myxosporeans at the species-level is mainly based on conventional methods. The 18S rRNA gene sequence of morphologically identified Myxobolus orissae infecting the gill lamellae of mrigal carp Cirrhinus mrigala was characterized in the present study. The plasmodia of M. orissae were small, elongated and white to pale in colour. Phylogenetically, the 18S rDNA nucleotide sequence of M. orissae was clustered with other gill-infecting Myxobolus spp. of cyprinids. The species closely related to M. orissae was M. koi (FJ841887) infecting the gill lamellae of Cyprinus carpio with 96% similarity. The carp fin-infecting Thelohanellus caudatus (KC865607) from India exhibited only 78% DNA sequence similarity with M. orissae. Low level of M. orissae infection on gill caused thickening of epithelial cells surrounding the plasmodium. Under stressful conditions, it is likely that such infection can easily spread in confined fish and may cause serious disease outbreaks and economical losses.

A myxozoan parasite belonging to the genus Thelohanellus Kudo, 1933 (Cnidaria, Myxosporea, Bivalvulida) was isolated from the fins of Labeo dero inhabiting Ranjit Sagar Wetland, Punjab, India. The plasmodium was 0.5-0.7 mm in diameter each containing 80- 100 number of myxospores. Myxospores were egg shaped to ovoidal in valvular view having bluntly pointed anterior and broad rounded posterior end measuring 8.36x 4.77 µm. Polar capsule was single, broadly pyriform in shape, measuring 4.77x3.98 µm in size containing a polar filament coiled perpendicular to the longitudinal axis of myxospore body making 7-9 turns. Blast analysis of 18S rDNA sequence of the isolate demonstrated 98% homogeneity with Thelohanellus sp.(KU155561, Unpublished), followed by91% with T. caudatus (KM252684) and Thelohanellus sp. FCO (KR819273). The intensity of infection was recorded to be light as indicated by fin plasmodial index (FPI = 1). In the present study, T. boggoti has been described using 18S rRNA gene and phylogenetic analysis using MEGA.6.