زیست شناسی علوم گیاهی
گروه آموزشی زیست شناسی ( عمومی- جانوری،گیاهی)
Exploring genes and pathways underlying intellectual disability (ID) provides insight into brain development and function, clarifying the complex puzzle of how cognition develops. As part of ongoing systematic studies to identify candidate ID genes, linkage analysis and next-generation sequencing revealed Zinc Finger and BTB Domain Containing 11 (ZBTB11) as a novel candidate ID gene. ZBTB11 encodes a little-studied transcription regulator, and the two identified missense variants in this study are predicted to disrupt canonical Zn2+-binding residues of its C2H2 zinc finger domain, leading to possible altered DNA binding. Using HEK293T cells transfected with wild-type and mutant GFP-ZBTB11 constructs, we found the ZBTB11 mutants being excluded from the nucleolus, where the wild-type recombinant protein is predominantly localized. Pathway analysis applied to ChIP-seq data deposited in the ENCODE database supports the localization of ZBTB11 in nucleoli, highlighting associated pathways such as ribosomal RNA synthesis, ribosomal assembly, RNA modification and stress sensing, and provides a direct link between subcellular ZBTB11 location and its function. Furthermore, given the report of prominent brain and spinal cord degeneration in a zebrafish Zbtb11 mutant, we investigated ZBTB11-ortholog knockdown in Drosophila melanogaster brain by targeting RNAi using the UAS/Gal4 system. The observed approximate reduction to a third of the mushroom body size—possibly through neuronal reduction or degeneration—may affect neuronal circuits in the brain that are required for adaptive behavior, specifying the role of this gene in the nervous system. In conclusion, we report two ID families segregating ZBTB11 biallelic mutations disrupting Zn2+-binding motifs and provide functional evidence linking ZBTB11 dysfunction to this phenotype.
The advent of high-throughput sequencing technologies has led to an exponential increase in the identification of novel disease-causing genes in highly heterogeneous diseases. A novel frameshift mutation in CNKSR1 gene was detected by Next-Generation Sequencing (NGS) in an Iranian family with syndromic autosomal recessive intellectual disability (ARID). CNKSR1 encodes a connector enhancer of kinase suppressor of Ras 1, which acts as a scaffold component for receptor tyrosine kinase in mitogen-activated protein kinase (MAPK) cascades. CNKSR1 interacts with proteins which have already been shown to be associated with intellectual disability (ID) in the MAPK signaling pathway and promotes cell migration through RhoA-mediated c-Jun N-terminal kinase (JNK) activation. Lack of CNKSR1 transcripts and protein was observed in lymphoblastoid cells derived from affected patients using qRT-PCR and western blot analysis, respectively. Furthermore, RNAi-mediated knockdown of cnk, the CNKSR1 orthologue in Drosophila melanogaster brain, led to defects in eye and mushroom body (MB) structures. In conclusion, our findings support the possible role of CNKSR1 in brain development which can lead to cognitive impairment.
درجه ای از دمانس یا فراموشی در بسیاری از موجودات زنده ازجمله انسان همراه با افزایش سن و پیر شدن ایجاد میشود. این گونه اختلالات ممکن است ناشی از عوامل ژنتیکی و بالینی متفاوتی باشد. در این پژوهش تعیین پلی مورفیسم ژن APOE به عنوان مهم ترین فاکتور ژنتیکی شناخته شده برای بیماری آلزایمر، در گروهی از سالمندان مبتلا به فراموشی در منطقه سیستان صورت گرفت و ارتباط آن با وضعیت چربی خون، سطح یون های فلزی خون و برخی ویژگیهای دموگرافیک مرتبط با سبک زندگی بررسی شد. هم چنین در پژوهش حاضر، ارتباط بین عوامل محیطی مربوط به سبک زندگی و فاکتور ژنتیکی APOE مورد بررسی قرار گرفت. با اخذ مجوزهای قانونی و گرفتن رضایت نامه از افراد شرکت کننده در مطالعه، پس از غربال گری افراد جمعیت هدف با استفاده از پرسشنامه استاندارد ) MMSE ) Mini Mental Estate Examination و هم چنین در نظر گرفتن نژاد سیستانی از گروه سالمندان بیمار و سالمندان سالم به عنوان شاهد نمونه خون تام تهیه شد. نمونه ها شامل 55 فرد بیمار و 00 فرد سالم بود. افراد سالم انتخاب شده از نظر سن، جنس و نژاد با گروه بیمار هم خوان بودند. از سرم خون آن ها جهت سنجش میزان چربی و میزان عناصر فلزی مس، آهن و روی استفاده شد. استخراج DNA از گلبول های سفید خون محیطی انجام گرفت و بررسی ژنوتیپ افراد برای ژن APOE با روش ( AS PCR ) allele specific PCR صورت پذیرفت. پارامترهای دموگرافیک شامل سن، جنسیت، سطح سواد، مصرف دخانیات و مواد مخدر، وجود سابقه خانوادگی برای بیماری و سابقه بیماری های قلبی و صدمه سر نیز برای هر یک از افراد بیمار و همین طور گروه شاهد مورد ارزیابی قرار گرفت. نتایج بیانگر وجود فراوانی بیشتر آلل E4 ژن APOE در میان سالمندان بیمار نسبت به سالمندان سالم بود. شایان ذکر است که میزان HDL خون سالمندان بیمار کمتر از افراد سالم بود درحالی که سطح فلز روی در خون گروه شاهد کمتر از گروه بیماران بود. به طورکلی فراوانی زنان مبتلا به فراموشی بیش تر از مردان بود. هم چنین میانگین سطح سواد در بیماران بسیار کمتر از گروه شاهد بود درحالی که مصرف مواد مخدر در بین بیماران شایع تر از سالمندان سالم بود. در دیگر فاکتورهای بررسی شده تفاوت معناداری میان دو گروه مورد مطالعه مشاهده نشد.
The central nervous system (CNS) is the most complex part of the human body, which controls a variety of cellular and molecular activities. Neurobehavioral functions of CNS play a vital role in making appropriate responses to the environmental stimuli. Some kind of such responses can be maintained in neural networks due to neuronal plasticity. When brain ages, or being damaged by means of genetic or environmental factors, memories will disappear gradually. Molecular mechanism of memory formation and disruption are studied during normal and diseased conditions, respectively. However, it is far to understand the complete scenario and we need a model organism to undertake specific studies and unravel the mystery of neuronal function. The fruit fly, Drosophila melanogaster possesses many characteristics, which enable neuroscientists to model wide range of complex behaviors and find their neural circuit. Even though, many human neurodegenerative disorders (NDDs) can be modeled in this insect and provide unique opportunities for effective therapeutic interventions. Here I summarized few points on the contribution of D. melanogaster in the neurobiology of learning and memory as well as human NDDs.
An urgent need for better understanding of memory is increasing as our aged population gets older and older. Extensive research on the biology of learning, memory and neurodegeneration is accelerating to meet this challenge. Drosophila melanogaster is shown to play an essential role in unraveling the genetics of learning and memory. Various behavioral assays on Drosophila model of human neurodegenerative diseases have been employed in a number of studies. Classical olfactory conditioning, courtship conditioning, and newly-introduced method based on predator-mediated fear induction are among the most widely applicable and reproducible ones. In this letter I wish to address some critical aspects of each protocol, though the given points can be considered as a general criticism for such kinds of experiments.
Abstract Introduction: Repeated heat shock (HS) stresses reduce the reproduction rate of Drosophila flies. Heat shock proteins (HSPs) protect cells against irreversible damages inducing heatinduced. Oxidative stress declines protective function of HSPs. Diploschistes ocellatus lichen aqueous extract possesses a strong antioxidant potential in vitro. Antioxidants can preserve HSPs function. Therefore, the present study for the first time investigated the cytoprotective effects of D. ocellatus aqueous extract against HS-mediated deleterious effects on reproductive function in Drosophila melanogaster. Methods: Three different types of culture media including control, 30% lichen extract, and 60% lichen extract were prepared. Adult D. melanogaster flies were placed on Delcour medium and allowed to lay eggs for 2 hours. Then the eggs were equally distributed between the culture media. After flies completed their life cycle, the adult enclosed flies were exposed to HS. To assess reproductive function, the newly emerged adult flies were transferred to the freshly prepared regular culture medium every three days for 3 times and finally adult offspring born to these flies were enumerated. Results: HS negatively affected the reproduction rate in flies in control group. Quantification of adult enclosed flies born to the D. ocellatus extract treated flies showed that lichen extract could negate the deleterious effects of HS on reproduction function of D. melanogaster in a dose-dependent manner. Conclusion: Diploschistes ocellatus aqueous extract attenuated the harmful effects of HS stress on reproductive function of D. melanogaster. The secondary metabolites present in D. ocellatus can be considered as a bona fide candidate in novel drug development to target reproductive diseases in which oxidative stress is involved. Moreover, it can be concluded that D. melanogaster is an ideal model organism to induce cellular stress in vitro and study therapeutic potential of lichen extracts.
Iran, despite its size, geographic location and past cultural influence, has largely been a blind spot for human population genetic studies. With only sparse genetic information on the Iranian population available, we pursued its genome-wide and geographic characterization based on 1021 samples from eleven ethnic groups. We show that Iranians, while close to neighboring populations, present distinct genetic variation consistent with long-standing genetic continuity, harbor high heterogeneity and different levels of consanguinity, fall apart into a cluster of similar groups and several admixed ones and have experienced numerous language adoption events in the past. Our findings render Iran an important source for human genetic variation in Western and Central Asia, will guide adequate study sampling and assist the interpretation of putative disease-implicated genetic variation. Given Iran’s internal genetic heterogeneity, future studies will have to consider ethnic affiliations and possible admixture.
Abstract: Background: Methamphetamine (MA) acts as a powerful oxidant and Rosmarinic acid (RA) is a powerful herbal antioxidant. Oxidative stress mediated by MA results in apoptosis and caspase-3 is one of the key enzymes in the apoptosis process. MA is able to epigenetically alter gene regulation. In this paper, to investigate the effects of RA on MA-mediated oxidative stress, changes in the level of casp3a mRNA has been demonstrated in zebrafish. Purpose: This study aims to investigate MA ability in imposing the brain cell to increase the synthesis of casp3a mRNA in zebrafish brain tissue. We hypothesized that a powerful antioxidant such as RA may be able to counteract MA-mediated oxidative stress and its consequences. For better penetration of RA across the blood brain barriers (BBBs), RA was combined with ZnO/chitosan nanoparticles. To evaluate whether MA with the concentration of 25 mg/l is anxiogenic or anxiolytic and the effects of RA on it, one-sided trapezoidal tank diving tests were applied for 3 groups of MA-treated, MA & RA-treated and saline as the control group. Study design: The animals were grouped in 3 treatment conditions for the behavioral test: control, MA, MA pretreated by RA, and 6 treatment conditions for the molecular test: control, RA, MA, MA cotreated with RA, MA cotreated with RA/ZnO/chitosan nanoparticle, and ZnO/chitosan nanoparticle. Then molecular and behavioral investigations were carried out and critical comparisons were made between the groups. Methods: MA solution was prepared with the concentration of 25 mg/l and RA solution was prepared by DPPH test with the antioxidant power about 97%. Each solution was administered by immersing 20 zebrafish for 20 minutes, once per day for a continuous 7 days. The level of casp3a mRNA was quantified by making use of qRT-PCR. One-sided trapezoidal tank diving test was applied to study behavioral alterations. Results: The qPCR analysis demonstrated the high potential of RA/ZnO/chitosan in counteracting the MA-mediated elevation in casp3a mRNA level. By the diving test of MA-treated fishes, MA found to be anxiolytic compared to the control. While the resulted diving pattern of the MA-treated animals pre-treated by RA was novel and different than both the control and MA-treated groups. Conclusion: The potential of RA combined to a suitable nanoparticle against MA-induced oxidative stress was supported. The high efficiency of ZnO/Chitosan in increasing RA penetration to the brain cells was evident. 25 mg/l of MA for zebrafish is anxiolytic. However, the molecular mechanisms involved in these processes are needed to be studied.
Honeybees have been directly linked to the environment due to the foraging behavior of collecting foods, which is why considered today as an environmental biomarker. According to the direct effect of pesticides and chemical pollutants on honey bees survival, this study was carried out to determine whether compounds toxic such as paraquat (PQ) and manganese (Mn) added to the food could influence the longevity of young honey bees which have no previous experience with chemicals. The study was conducted on one-day-old bees that make it possible to control their age and survive under laboratory conditions. Frames containing Apis mellifera meda pupae were kept in an incubator (33° C, 40% humidity). One-day-old bees were collected from the frames and placed in cages in groups of 100. One-day-old bees were exposed to preliminary concentrations of PQ (100 to 1000 mg L-1) and Mn (323.75 to 5665.59 mg L-1) diluted in the sucrose solution (50%). Concentrations of 55.69 and 106.19 mg L-1 were obtained as LC10 values for PQ and Mn, respectively. In addition, LC25 of PQ and Mn were obtained at 106.87 and 346.41 mg L-1, respectively. To assay the effects of sub-lethal concentrations on longevity and survival, honey bees daily received 20 mL of sucrose solution containing LC10 and LC25 of PQ and Mn. Data were analyzed using SPSS 19.00. Results showed that LC10 and LC25 of PQ induced mortality of honeybees after 5 days of treatment, while in Mn treatment, 10 and 25 percent mortality were observed after 14 days which significantly was longer than PQ treatments (P≥0.05). Result confirmed that the treated bees with LC10 and LC25 of PQ were significantly more sensitivite in shorter time than Mn treatments. Since Mn unlike PQ, is naturally present in vertebrates and invertebrates such as honey bees and plays an important role in their immune system changes and the metabolism of macromolecules, manganese accumulation as a heavy metal in the honey bee’s body requires longer time to demonstrate its negative impact on the physiology of the honey bee. According to the results of this study, which indicate the noxious on the life span and survival of honey bees, paying attention to the proper application of chemical pesticides to reduce their negative effects on the health of living organisms is needed.
Biogenic amines as important behavior modulators show similar physiological properties in vertebrates and invertebrates. The less complex brain in honey bees make suitable them as model organisms for studying the function of biogenic amines. In honeybees, octopamine mediates sucrose reward in learning but little was known about this behavior in honey bee under stress. The proboscis extension response (PER) as a classical learning experiment present when the bee antennae are stimulated with sucrose solution, then she extends her proboscis in food expectation. We studied whether increasing sucrose sensitivity by octopamine can improve learning performance in honey bee under chemical stress. To obtain newly emerged bees, frames of Apis mellifera meda with sealed brood were incubated (33°C, 40% humidity). One-day- bees were brushed off the combs and was individually mounted in plastic holders. Then using an adhesive tape strip, the head and the thorax was fixed while allowing them to move their antennae and mouthparts. To determine individual sensitivity to sucrose (30%), the bee antennae were touched with sucrose solution. The sum of PERs to stimulation constituted the gustatory response score (GRS) of a bee. The bees were treated with LC10 as a sub-lethal concentration of diazinon, imidacloprid, and thymol (0.22, 29.04, and 0.91 mg L-1, respectively), separately and their GRS were recorded prior to octopamine injection. Octopamine (10-3 mol L–1) was injected into the thorax. GRS in the treated bees was tested again 30 min after injection and the difference between initial sensitivity and sensitivity 30 min after injection was calculated. Two weeks later, GRS was recorded in the treated bees that became old foragers. Data were analyzed using SPSS 19.0. Results showed that learning performance of the treated bees with pesticides decreased significantly compared to control. In addition, results demonstrated that octopamine improved learning performance in newly emerged bees (P≤0.05) which were significantly higher than control. In bees with low initial sensitivity for sucrose did octopamine increase sensitivity; while this result was not significantly different between the treated bee with pesticides. Results showed when the newly emerged bees which were previously treated with octopamine became older; imidacloprid treated bees were more sensitivity to sucrose compared to other treatments (P≤0.05). It was assumed that the observed increase in sensitivity was achieved through increased activation of octopamine receptors in the brain of bees which is needed to study in the future.