Reviewing Interspecies Interactions as a Driving Force Affecting the Community Structure in Lakes via Cyanotoxins

The escalating occurrence of toxic cyanobacterial blooms worldwide is a matter of concern. Global warming and eutrophication play a major role in the regularity of cyanobacterial blooms, which has noticeably shifted towards the predomination of toxic populations. Therefore, understanding the effects of cyanobacterial toxins in aquatic ecosystems and their advantages to the producers are of growing interest. In this paper, the current literature is critically reviewed to provide further insights into the ecological contribution of cyanotoxins in the variation of the lake community diversity and structure through interspecies interplay. The most commonly detected and studied cyanobacterial toxins, namely the microcystins, anatoxins, saxitoxins, cylindrospermopsins and β-N-methylamino-L-alanine, and their ecotoxicity on various trophic levels are discussed. This work addresses the environmental characterization of pure toxins, toxin-containing crude extracts and filtrates of single and mixed cultures in interspecies interactions by inducing different physiological and metabolic responses. More data on these interactions under natural conditions and laboratory-based studies using direct co-cultivation approaches will provide more substantial information on the consequences of cyanotoxins in the natural ecosystem. This review is beneficial for understanding cyanotoxin-mediated interspecies interactions, developing bloom mitigation technologies and robustly assessing the hazards posed by toxin-producing cyanobacteria to humans and other organisms.Peer reviewe

Interspecies interactions between Microcystis aeruginosa PCC 7806 and Desmodesmus subspicatus SAG 86.81 in a co-cultivation system at various growth phases

In lakes, cyanobacterial blooms are frequently associated with green algae and dominate the phytoplankton community in successive waves. In the present study, the interactions between Microcystis aeruginosa PCC 7806 and Desmodesmus subspicatus were studied to clarify the probable ecological significance of algal secondary metabolites; focusing on the role of cyanotoxin ‘microcystin-LR’(MC-LR). A dialysis co-cultivation technique was applied where M. aeruginosa was grown inside and D. subspicatus was cultured outside of the dialysis tubing. The concentration of the intra- and extracellular MC-LR and the growth of two species were measured at different time points over a period of one month. Additionally, the growth of the two species in the culture filtrate of one another and the effect of the purified MC-LR on the growth of the green alga were studied. The results indicated that the co-existing species could affect each other depending on the growth phases. Despite the early dominance of D. subspicatus during the logarithmic phase,M. aeruginosa suppressed the growth of the green alga at the stationary phase, which coincided with increased MC production and release. However, the inhibitory effects of Microcystis might be related to its other extracellular metabolites rather than, or possibly in addition to, MCPeer reviewe

Desmodesmus subspicatus co-cultured with microcystin producing (PCC 7806) and the non-producing (PCC 7005) strains of Microcystis aeruginosa.

Although microcystins (MCs) are the most commonly studied cyanotoxins, their significance to the producing organisms remains unclear. MCs are known as endotoxins, but they can be found in the surrounding environment due to cell lysis, designated as extracellular MCs. In the present study, the interactions between MC producing and the non-producing strains of Microcystis aeruginosa, PCC 7806 and PCC 7005, respectively, and a green alga, Desmodesmus subspicatus, were studied to better understand the probable ecological importance of MCs at the collapse phase of cyanobacterial blooms. We applied a dialysis co-cultivation system where M. aeruginosa was grown inside dialysis tubing for one month. Then, D. subspicatus was added to the culture system on the outside of the membrane. Consequently, the growth of D. subspicatus and MC contents were measured over a 14-day co-exposure period. The results showed that Microcystis negatively affected the green alga as the growth of D. subspicatus was significantly inhibited in co-cultivation with both the MC-producing and -deficient strains. However, the inhibitory effect of the MC-producing strain was greater and observed earlier compared to the MC-deficient strain. Thus, MCs might be considered as an assistant factor that, in combination with other secondary metabolites of Microcystis, reinforce the ability to outcompete co-existing species.Peer reviewe

Still challenging : the ecological function of the cyanobacterial toxin microcystin – What we know so far

Microcystins (MCs) are the most commonly studied cyanotoxins. While these past studies have mainly focused on the toxicity of MCs, the evolutionary history of life has shown that toxicity can be considered as an assigned role to MCs. Nowadays, there is a growing interest in understanding the importance of cyanotoxins in any of the physiological processes or beyond at the ecological level. This review evaluates variously proposed intracellular and extracellular functions of MCs and how they benefit the producing cyanobacterium. However, the strain-specific and divergent laboratory and field results obtained to date have made it difficult to generalize.Peer reviewe

The exact synchronization timing between the cleavage embryo stage and duration of progesterone therapy-improved pregnancy rates in frozen embryo transfer cycles: A cross-sectional study

Background: Synchronization between the embryonic stage and the uterine endometrial lining is important in the outcomes of the vitrified-warmed embryo transfer (ET) cycles. Objective: The aim was to investigate the effect of the exact synchronization between the cleavage stage of embryos and the duration of progesterone administration on the improvement of clinical outcomes in frozen embryo transfer (FET) cycles. Materials and Methods: 312 FET cycles were categorized into two groups: (A) day- 3 ET after three days of progesterone administration (n = 177) and (B) day-2 or -4 ET after three days of progesterone administration (n = 135). Group B was further divided into two subgroups: B1: day-2 ET cycles, that the stage of embryos were less than the administrated progesterone and B2: day-4 ET cycles, that the stage of embryos were more than the administrated progesterone. The clinical outcome measures were compared between the groups. Results: The pregnancy outcomes between groups A and B showed a significant differences in the chemical (40.1% vs 27.4%; p = 0.010) and clinical pregnancies (32.8% vs 22.2%; p = 0.040), respectively. The rate of miscarriage tended to be higher and live birth rate tended to be lower in group B than in group A. Also, significantly higher rates were noted in chemical pregnancy, clinical pregnancy, and live birth in group A when compared with subgroup B2. Conclusion: Higher rates of pregnancy and live birth were achieved in day-3 ET after three days of progesterone administration in FET cycles. Key words: Endometrium, Embryo transfer, Pregnancy, Live birth, Progesterone

The CRISPR growth spurt: from bench to clinic on versatile small RNAs

Clustered Regulatory Interspaced Short Palindromic Repeats (CRISPR) in association with CRISPR associated protein (Cas) is an adaptive immune system, playing a pivotal role in the defense of bacteria and archaea. Ease of handling and cost effectiveness make CRISPR-Cas system an ideal programmable nuclease tool. Recent advances in understanding the CRISPR-Cas system have tremendously improved its efficiency. For instance, it is possible to recapitulate the chronicle CRISPR-Cas from its infancy and inaugurate a developed version by generating novel variants of Cas proteins, subduing off-target effects and optimization of innovative strategies. In summary, CRISPR-Cas system could be employed in a number of applications including providing model systems, rectification of detrimental mutations, and antiviral therapies

Die interspezifischen Wechselwirkungen zwischen Cyanobakterien und der Grünalge – die Funktion von Cyanotoxinen im Ökosystem

Over the past decades, cyanobacteria have attracted the researcher’s attention due to their ability to produce cyanotoxins. Among cyanotoxins, microcystins (MCs) are the most commonly studied. However, their significance for the producing species beyond their toxicity is still mysterious (was reviewed in Paper I). In the present study, the interactions between a common bloom-forming cyanobacterium “Microcystis aeruginosa” and a green alga “Desmodesmus subspicatus” were studied to provide more insights into the ecological importance of the algal secondary metabolites concerning MCs. To achieve this, a dialysis co-cultivation system was established. First, M. aeruginosa PCC 7806 and D. subspicatus were co-cultured (1:1) at different phases of growth (Paper II). Second, D. subspicatus was co-cultured with M. aeruginosa PCC 7806 and PCC 7005 (toxic and non-toxic strains, respectively) that were grown to the stationary phase of growth (Paper III). As a result, the concentration of intracellular and extracellular (inner and outer membrane) MC-LR was quantified using liquid chromatography-tandem mass spectrometry and the cell density was monitored using a haemocytometer under the light microscopy. The growth of M. aeruginosa PCC 7806 and D. subspicatus in the culture filtrates of each other and the effects of toxic M. aeruginosa crude extracts on the growth of D. subspicatus were studied as well (Paper II). The results provided clues to the involvement of the algal secondary metabolites in the interspecies interplay. The growth of the two species was inhibited in the culture filtrates of one another (˃ 25% exudates). The MC-containing crude extracts (˃ 140 µg/L) inhibited the growth of green alga. Moreover, the co-cultured species influenced the growth of each other negatively depending on the stages of the growth. During the exponential phase of growth, the green alga inhibited the growth and MC production but has not influenced the MC release. While, at the stationary phase of growth, MC production and release were enhanced, coinciding with the inhibition of the growth of green alga (Paper II). Moreover, MC-producing strain excluded the green alga greater and earlier compared to non-toxic strain. The MC-producing M. aeruginosa benefited from MC, in addition to or rather than the other secondary metabolites, to improve its fitness and the greater exclude of the green alga. However, inhibition of the growth of green alga at the concentrations of MC-LR above the environmental levels may explain the frequent co-existence of the green algae with cyanobacterial blooms. Moreover, the results indicated that the diffusion rate of extracellular MC-LR across the dialysis membrane was positively related to the time and negatively to the concentration of extracellular MC-LR.In den letzten Jahrzehnten haben Cyanobakterien viel Aufmerksamkeit auf sich gezogen, weil sie Cyanotoxine produzieren können. Die am häufigsten untersuchten Cyanotoxine sind die Microcystine (MCs). Neuere Studien haben die Rolle der MCs in den ökologischen und physiologischen Prozessen herausgestellt (Publikation I). In der vorliegenden Studie wurden die Wechselbeziehungen zwischen dem Cyanobakterium Microcystis aeruginosa und der Grünalge Desmodesmus subspicatus untersucht, um die ökologische Rolle der Algen-Sekundärmetaboliten, insbesondere der MCs, zu klären. Daher wurde ein Dialyse-Co-Kultursystem entworfen. Zuerst wurden die MC-produzierende M. aeruginosa PCC 7806 und D. subspicatus in verschiedenen Wachstumsstadien co-kultiviert (Publikation II). Zusätzlich wurde D. subspicatus mit den toxischen und nichttoxischen Stämmen von M. aeruginosa (PCC 7806 und PCC 7005), die bis zur stationären Wachstumsphase gezüchtet wurden, co-kultiviert (Publikation III). Die Konzentration des intrazellulären und extrazellulären (innere und äußere Membranen) MC-LR wurde mit der LC-MS/MS quantifiziert. Die Zelldichte der Arten wurde mit der Zählkammer und der Lichtmikroskopie gezählt. Anschließend wurde das Algenwachstum in den Kulturfiltraten gemessen und die Auswirkungen des Rohextrakts von toxischem M. aeruginosa auf das Wachstum der Grünalge bestimmt. Die Ergebnisse liefern Hinweise auf die Beteiligung der Algen-Sekundärmetaboliten an den interspezifischen Wechselwirkungen. Das Algenwachstum wurde in den Kulturfiltraten bei erhöhtem Anteil der Filtrate gehemmt. Das MC-haltige Rohextrakt von M. aeruginosa hemmte auch das Wachstum der Grünalge. Die co-kultivierten Arten wurden in Abhängigkeit von den Wachstumsphasen negativ beeinflusst. Während der exponentiellen Wachstumsphase inhibierte die Grünalge das Wachstum und die MC-Produktion von M. aeruginosa. In der stationären Wachstumsphase wurde die MC-Produktion und die Freisetzung von Microcystis gesteigert und das Wachstum der Grünalgen gehemmt. Die MC-produzierende Stamm von M. aeruginosa hemmte das Wachstum der Grünalge früher und in höherem Umfang als der MC-defiziente Stamm. Die MC-produzierende Microcystis profitierte vom MC in der Kombination mit oder anstelle der anderen Sekundärmetaboliten, mit dem Effekt, ihre Fitness zu verbessern und die Grünalge auszukonkurrieren. Die Hemmung des Grünalgenwachstum bei Konzentrationen über dem Umweltniveau der MCs kann jedoch die Koexistenz der Grünalgen und der Cyanobakterien erklären. Andererseits zeigten die Ergebnisse, dass die Diffusionsrate des MC-LR positiv abhängig von der Zeit und negativ von der Konzentration des extrazellulären MC-LR war

Preparation and evaluation of antibactrial effect of polysaccharide nanocomposite contains curcumin for prevention of dental bacterial biofilm formation

Introdution: One of the main reasons of dental caries is the increase in microbial activity in the oral cavity. Streptococcus mutans (S. mutans) is the main etiological agent in dental caries. The aim of this study was preparation and evaluation bio-nanocomposite Chitosan CS-St-MMT encapsulated with Curcumin fabricated by precipitation and ionic gelation method and antimicrobial effect was investigated. Methods: The present study was an experimental one. Physiochemical characteristics and structural characterization of nanocomposite were evaluated by the from the perspective of in vitro efficiency, drug release profile, nanocomposite size, zeta potential, surface morphology and FTIR spectra. Results: The optimal formulation nanocomposites had the average particles size of 35.9 nm and zeta potential 37.2 mV and Curcumin entrapment efficiency of 91%. The maximum release of the drug for this Nanosystem was about 80%, indicated the control of release in the presence of montmorillonite compared with the absence of montmorillonite nanocomposite. In FTIR studies, absorption peak was observed for curcumin, starch, chitosan and montmorillonite in nanocomposites, which indicated the mixing of montmorillonite and curcumin in nanocomposites. Finally, the antibacterial activity of bio nanocomposite against Streptococcus mutans was assessed. Conclusion: Curcumin-loaded bio nanocomposite hindered the formation of biofilm on dental models very effectively, because of the improvement in the encapsulated curcumin stability and increased water solubility

Missed estradiol determination resulting in oocyte retrieval and embryo development following controlled ovarian hyperstimulation at early pregnancy: Case report

This paper is a case report on the success of oocyte retrieval and good quality embryo development following controlled ovarian hyperstimulation at early pregnancy. A 30-year-old patient underwent controlled ovarian hyperstimulation by gonadotropin-releasing hormone agonist long protocol. On the day of oocyte collection, a 5-week gestational sac was observed by exact sonography monitoring. However, via ultrasound guided follicle puncture, 7 oocytes were collected. After intarcytoplasmic sperm injection, 3 developed good quality embryos were cryopreserved. Moreover, the natural pregnancy was continued and finally a healthy live birth was achieved. Despite physiological hormonal changes during pregnancy, the follicular growth occurred and followed by oocyte retrieval and embryo development, subsequently

Evaluating Poly-Aromatic Hydrocarbons in respiratory zone of the asphalt workers in Tehran city

Introduction: PAHs are organic compounds with benzenic rings that releas from hot asphalt as incomplete combusting. These compounds are one of the major concern in scientific societies, workplace and environment due to their stability, bioaccumulation, carcinogenic and mutagenic effects. Since asphalt workers are exposed to PAHs frequently in their job, in this study it was attempted to evaluate respiratory exposure of asphalt workers to PAHs in their breathing zone. .Material and Method: In this study air samples of the asphalt workers were collected in accordance with the NIOSH 5506 method using PTFE filter and XAD-2 adsorbent. The ultrasonic bath and acetonithrile are used in order to extract the analytes from the filter and adsorbent. Also, the samples were analyzed by HPLC-UV. .Result: In all samples, Finisher assistance and oilman with 1754.48 ng/m3 , 24.65 ng/m3 had maximum and minimum exposed to ∑PAH, respectively. Among the PAHs compounds, which asphalt workers exposed to, Naphtalene had the highest concentration. Among different asphalt workers tasks, screedman expoused to PAHs, had a significant difference. . Conclusion: Evaluation of Polycyclic aromatic hydrocarbons concentrations in the breathing zone of asphalt workers indicated that exposure to these compounds were below the occupational exposure limits recommended by NIOSH, OSAH, ACGIH and Iranian OEL. Due to the highly carcinogenic potential of some of these compounds and absence of occupational exposure limits for these compounds, likes Chrysene and Benzo (a) Anthracene, it is strictly recommended to employ engineering controls and using suitable PPEs. This study also indicated that the exposure to PAHs in the most asphalt workers tasks had significant differences, and it can be due to proximity of the workers to the source of hot asphalt and also exposure to the exhaust gases that releasesd from the construction machinery