Hungarian researchers reveal new anatomical features of the brain’s reward system

Researchers from the ELKH Institute of Experimental Medicine (IEM) and the ELKH Research Centre for Natural Sciences (TTK), also affiliated with the University of Veterinary Medicine have uncovered new genetic features of the brain’s reward system. The research, carried out by Ferenc Mátyás, head of the Neuronal Networks and Behaviour Research Group, and his PhD student Ákos Babiczky, focused on the anatomical connections between the so-called medial prefrontal cortex (mPFC) and two ancient regions of the central nervous system, the striatum and the tegmentum, in mice. The latter two form the pathway where dopamine the ‘reward molecule’ orchestrates learning and other reward-related processes. A study presenting the results of the research has been published in the prestigious international journal eLife.

Although this system has been intensively investigated in the previous decades, certain molecular features were not completely elucidated. Unfortunately, without a precise anatomical framework, functional investigations cannot be carried out reliably. For example, it was not clear whether a single neuron of the mPFC could simultaneously innervate the striatum and the tegmentum.

Pyramidal cells of the mPFC labelled with a green fluorescent protein are separated from genetically
different populations labelled with red and blue. The method is reliably applicable to differentiate distinct neuron populations.

In order to clarify this, first, the researchers described where striatum- and tegmentum-innervating neurons are localized in the mPFC, using fluorescent microscopy, several genetically modified mouse strains and special viral constructs. The results clearly showed that the two populations occupy different layers and subregions in the mPFC and they also revealed that these neurons have different genetic identities. Next, they directly compared them and found that there is minimal overlap between the two populations indeed. Furthermore, the researchers also demonstrated that these two populations have different connections with other brain regions as well.

Virally labelled mPFC pyramidal neurons. The axons of these cells can be followed
throughout the whole brain.

These new results implicate that the mPFC – widely known as one of the most important higher order regulators of behavior and personality – can modulate the activity of the striatum and the tegmentum independently. This can be directly tested in the future, because the experimental approach described by the authors of this study published in the journal eLife can easily be applied to physiological and behavioral experiments. Untangling these connections at the anatomical and functional level can help us understand the healthy operation of the reward system as well as its malfunctions, like addiction.

Fluorescently labelled axons in the tegmentum (left) and in the striatum (right). The density of these
axons are visibly different in the two regions.

Publication:

Ákos Babiczky, Ferenc Mátyás (2022). Molecular characteristics and laminar distribution of prefrontal neurons projecting to the mesolimbic system. eLife. doi: 10.7554/eLife.78813

Nurturing developing neurons: How microglia, the main immune cells of the brain contribute to brain development by interacting with newborn neurons

The “Lendület” – Momentum Laboratory of Neuroimmunology of the ELKH Institute of Experimental Medicine (IEM) led by Ádám Dénes was the first to describe the presence of a direct link between microglia cells and the cell body of developing neurons. The researchers also revealed the role of these contacts in brain development. The discovery may be of crucial importance for understanding the mechanisms of brain immune processes that often underlie neurodevelopmental disorders and related neuropathologies. The results of the study have been published in the prestigious international journal Cell Reports.

Microglia are recognized by the scientific community as the main immune cells of the central nervous system and the main regulators of inflammatory processes in the brain. The involvement and altered function of microglia have been demonstrated in the pathogenesis of most neurological diseases, such as stroke, Alzheimer’s disease, Parkinson’s disease, epilepsy, dementia and amyotrophic lateral sclerosis (ALS). The role of inflammatory processes and microglia in neurodevelopmental disorders is also increasingly recognized. The research group has accumulated a substantial body of knowledge in the field of microglia-neuron interactions, with several internationally visible publications in recent years. Among others, the group has discovered a novel form of interaction between microglia and the cell body of neurons, named somatic junctions, and revealed their role in microglia-mediated neuroprotection in the adult brain. Although the important role of the microglia in brain development has been pointed out in many previous studies, it was not known, which cell-to-cell communication mechanisms allow microglia to influence neuronal development and the formation of complex neuronal networks.

Microglial processes establish direct contacts on the cell bodies of developing neurons from embryonal day 15 (E15), throughout postnatal development and during postnatal neurogenesis. These contacts possess a specialized structural and molecular composition, as neuronal mitochondria and vesicles are enriched at these sites, with the accumulation of the microglia-specific P2Y12-receptors on contacting microglial processes. Acute inhibition of these receptors leads to inhibition of contact formation, while genetic deletion of P2Y12 receptors results in disturbed cortical cytoarchitecture.

Among the members of Ádám Dénes’ research group, Csaba Cserép and his student Dóra Anett Schwarcz played an outstanding role in the implementation of the research program, with further contribution by the research group of István Katona at IEM. During their investigations, the researchers used both high-resolution molecular anatomy techniques, combined light- and electron microscopy, and ex vivo imaging studies. Using a multifaceted approach, the researchers proved the presence of direct connections between microglia and developing neurons both during embryonic development and after birth. The specific, dynamically changing anatomical connections between microglia and developing, immature neurons resemble in many respects somatic junctions previously discovered by the research group, and their unique structure allows microglia to continuously monitor and effectively influence the development and networking of neurons. The significance of this discovery is illustrated by the fact that blockade of communication through these interactions sites prevents the development of normal cortical structure. Microglia should therefore be regarded as an important regulatory cell type in brain development, and a better understanding of their function may help in the development of therapies for neurodevelopmental disorders and other conditions.

A) Confocal laser scanning microscopic image of embryonal brain shows the distribution of microglia (green) and developing neurons (red). White arrows point to the enrichment of microglia. B) Microglia (green) are enriched in the subgranular zone of the hippocampal dentate gyrus. Developing neurons (red) are contacted by microglial processes, mature granule cells are blue. C-D) High resolution images show some examples of microglia-contacts in embryonal (C) and the adult brain (D), white arrows point to contact sites. Scale bar is 200 µm on A, 100 µm on B, 5 µm on C and 10 µm on D.

This research was supported by the following grants:

ERC-CoG 724994, the Hungarian Academy of Sciences “Lendület” – Momentum Programme LP2016-4/2016 and LP2022-5/2022, the Hungarian-Chinese Applied Research and Development Cooperation Programme 2020-1.2.4-TÉT-IPARI-2021-00005, the Hungarian Academy of Sciences NKFIH. Csaba Cserép (UNKP-20-5) and Balázs Pósfai (UNKP-20-3-II) have also received funding from the National R&D Funding Programme of the Hungarian National Research Council. Anett Scwarcz received a grant from the Richter Gedeon Talentum Foundation. István Katona was supported by the National Brain Research Programme (2017-1.2.1-NKP-2017-00002) and the National Research and Technology Foundation’s Lifeline Programme (129961).

Publication:

Csaba Cserép*, Anett D. Schwarcz, Balázs Pósfai, Zsófia I. László, Anna Kellermayer, Zsuzsanna Környei, Máté Kisfali, Miklós Nyerges, Zsolt Lele, István Katona, Ádám Dénes* (2022). Microglial control of neuronal development via somatic purinergic junctions. Cell Reports. doi: 10.1016/j.celrep.2022.111369

Zsolt Molnár, scientific advisor of the Centre for Ecological Research has been elected a member of the Academia Europaea

The Academia Europaea (European Academy of Sciences) has elected ethnoecologist Zsolt Molnár, a Doctor of the Hungarian Academy of Sciences (MTA), scientific advisor at the Centre for Ecological Research (CER), and head of the Traditional Ecological Knowledge Research Group, one of its members.

A staff member of the CER Institute of Ecology and Botany, Molnár researches the traditional and local ecological knowledge of shepherds and other farmers in Hungary, Transylvania, Serbia, Mongolia and Iran. His research areas include ethnobotany, historical landscape ecology, the mapping of Hungarian vegetation, landscape change, ecosystem services, nature conservation management, biodiversity monitoring and the further development of agricultural regulations.

Founded in 1988, the Academia Europaea has more than 4,500 members, including close to 80 Nobel laureates. The aim of the prestigious pan-European institution includes promoting and disseminating the results of European research, supporting interdisciplinary and international research collaborations, and raising social awareness of the usefulness of such scientific research.

Balázs Surányi, scientific advisor of the Hungarian Research Centre for Linguistics, has been elected a member of Academia Europaea

The Academia Europaea (European Academy of Sciences) has elected Balázs Surányi, PhD in Linguistics, lecturer at the PPKE BTK Institute of English and American Studies and scientific advisor at the ELKH Research Centre for Linguistics (NYTK), as one of its members.

Surányi’s main areas of research within the field of linguistics are Hungarian and English syntax and its interface with information structure, semantics (meaning), intonation (sound pitch), pragmatics (the science of signs and sign systems), information structure and prosody (versification), the interface between pragmatics and prosody, and experimental pragmatics.

Founded in 1988, the Academia Europaea has more than 4,500 members, including close to 80 Nobel laureates. The aim of the prestigious pan-European institution includes promoting and disseminating the results of European research, supporting interdisciplinary and international research collaborations, and raising social awareness of the usefulness of such scientific research.

FI Kövesligethy Radó Seismological Observatory launches new yearbook series entitled Epicentrum

The Kövesligethy Radó Seismological Observatory of the ELKH Research Institute of Earth Physics and Space Science (FI) launched a new yearbook series named Epicentrum in 2022.

The aim of the series is to present the earthquakes that occurred in Hungary and the surrounding countries in a given year with a scientific approach, but in a concise and easy-to-understand way. In the publications FI researchers also provide information on those earthquakes that were felt in Hungary and on large earthquakes that occurred around the world. In addition to up-to-date and interesting facts, the volume also includes phenomena detected by the Hungarian national seismological network managed by FI, as well as the earthquakes occurred in Croatia that could be felt in Hungary. The editors hope the publication will provide readers with a wide range of useful information.

The title of the first volume of the series is Epicentrum 2020 and presents events observed in 2020. The Hungarian language yearbook can be freely downloaded in PDF format from this link.

CER evolutionary biologist summarizes research findings on formation of cells with a nucleus

The journal Nature Ecology and Evolution asked István Zachar, senior fellow of the Institute of Evolution of the ELKH Centre for Ecological Research (CER) to assess a study on the causes of the formation of eukaryotic cells and also to evaluate the discovery in a separate opinion article. Zachar, a Hungarian evolutionary biologist believes the research will help bring us closer to understanding how eukaryotes – multinucleated organisms – formed approximately two billion years ago.

Animals, plants and all higher life forms are made up of eukaryotic cells, which differ from bacteria in many respects. Among other things, they have a nucleus, and the energy production that takes place within them is carried out by tiny cell organelles, known as mitochondria, which billions of years ago were also independent bacteria themselves. But how did eukaryotic cells come into existence? What kind of cells were their antecedents, and what evolutionary transitions led to their association with the antecedent of the mitochondrion? And finally, how did the eukaryotic life that populates the Earth originate? At this point in time, though evolutionary biologists have only been able to speculate on these questions, step by step they are getting closer to the real events.

István Zachar is researching the beginning point of the eukaryotic transition – the step that started the entire process. “The origin of eukaryotes is particularly interesting because it was at this time that two prokaryotic cell lineages finally merged. It seems that this was a unique and unrepeatable event in the history of life on Earth. It cannot be compared with any other major evolutionary transition,” explains Zachar. “Eukaryotic cells appeared roughly two billion years ago. The transitional forms created during the path leading to the formation of eukaryotes have not survived, so we have little information about them. We know that different prokaryotic cells came into close contact with each other and became eukaryotes, but there is no consensus on many fundamental questions, such as whether the mitochondrion was formed first or the nucleus,” the researcher emphasizes.

“We are not aware of any ‘missing links’, i.e. cells in an intermediate state, half prokaryotic, half eukaryotic, but we do know that eukaryotic organisms can achieve a level of complexity that is unimaginable in the case of prokaryotes,” continues Zachar. The transformation into a eukaryote clearly brought notable advantages, but even more exciting is the question of how this change occured.

According to some researchers, the development of eukaryotic cells began when the ancient host cell ingested another bacterium, but did not digest it. Others believe the host was not even a predator, and that the bacterium could have been a parasite infecting the host. Regardless of the explanation, the end result is the same: the host transformed the captured bacteria into its own cell organelle. This is how the mitochondrion was formed that is today responsible for the energy-producing processes of all eukaryotic cells. Endosymbiosis, i.e. an internal cooperation beneficial to both parties, was established between the two cells, in the framework of which the host cell received energy from the mitochondria, and in return the host provided it with food and security. Not only did the formation of mitochondria and eukaryotic cells only take place on a single occasion during the process of evolution, the two processes happened close to each other in time. As a result, evolutionary biologists have theorized that these two phenomena are very closely related.

But what were the specific benefits of taking in mitochondria, according to these theories? Cellular respiration was transferred to mitochondria, allowing eukaryotic cells to grow much larger than their prokaryotic ancestors. In addition, this freed the cell membrane of the host cells and they became suitable for many other tasks. For example, they were able to switch to a predatory lifestyle, which further increased their success rate.

The study evaluated by István Zachar examined whether the hypothesis that the mitochondrion provided an extremely large energetic advantage to early eukaryotes, since energy production took place inside the cells, was correct. It is estimated that this could have resulted in an energy gain of up to 200,000 times. Modern mitochondria certainly do produce energy efficiently. However, the authors of the study published in the journal Nature Ecology and Evolution also examined how much energy gain can be expected if we do not use modern eukaryotic hosts and current mitochondria as a basis, but the functioning of their ancestors who lived two billion years ago and had not yet adapted so perfectly to the division of labor.

The results found that the assumed energy gain virtually disappears. “Based on the new study, the theory based on the energetic advantage of mitochondria, according to which eukaryotic complexity cannot be achieved without mitochondria, is brought into question. Such models have far-reaching implications for the study of the origin of eukaryotes. These new findings reinforce the theory that mitochondria were not essential for the development of eukaryotes, but rather that the evolutionary innovations of nucleated cells came about gradually, ‘by themselves’, without the help of mitochondria, and that the inclusion of mitochondria only happened later,” summarizes Zachar .

There is increasing evidence that prokaryotic cells could also have achieved the greater complexity associated with the eukaryotic state independently. This is made probable by the fact that there are eukaryotic cells that have lost their mitochondria, but are actively moving, and that there are also prokaryotes that are able to engulf others – previously thought to be an ability possessed only by eukaryotes – and can reach significant complexity and size even without mitochondria. While there are still many unanswered questions about the origin of advanced nucleated life on Earth, evolutionary biologists are certainly getting ever closer to solving the biggest mysteries.

 

PIANOFORTE European Radiation Protection Research Partnership Program launched with the cooperation of EK-CER

With the cooperation of ELKH Centre for Energy Research (EK-CER), the European Partnership for Radiation Protection Research will contribute to improving the protection of the public, workers, patients and the environment from environmental, occupational and medical exposure to ionizing radiation. It brings together 58 partners representing 22 European Union countries as well as the United Kingdom and Norway, and is coordinated by the French Institute for Radiation Protection and Nuclear Safety (IRSN). It is co-financed by the European Union’s EURATOM program and the Member States of the participating countries. Through the research activities that will be carried out within its framework, PIANOFORTE will contribute to the implementation of European policies such as the European plan to combat cancer, the green pact for growth, and the implementation of the roadmap for reducing industrial and natural risks.

Launched on June 14, 2022 in Paris, the PIANOFORTE research partnership has the ambition to improve knowledge and promote innovation in the field of radiation protection for the benefit of better protection of the public, patients, workers and the environment in all scenarios of exposure to ionizing radiation.

Through the scientific challenges it will address, this partnership aims to contribute to priority European policies such as the fight against cancer (European Cancer Action Plan), the protection of health from environmental risks (Green Pact for Growth) and finally the improvement of anticipation and resilience in disaster situations (implementation of the Sendai Framework for Disaster Risk Reduction).

Within this partnership, at least three calls for proposals, open to the entire European research community for radiation protection, will be organized between 2023 and 2025. They will focus on the following four themes:

  • improving patient radiation protection in relation to the use of ionizing radiation in the medical field
  • a better comprehension of variability of individual response to exposure to ionizing radiation
  • the study of mechanisms involved in chronic exposure to low doses of ionizing radiation
  • the improvement of anticipation capacities and resilience in nuclear or radiological crisis situations and post-accident management.

Particular attention will be paid to the involvement of all stakeholders (authorities, civil society, radiation protection practitioners, experts, etc.) in the priority setting of the scientific topics that will be the subject of calls for tender and with respect to the question of translating this research into actual impact for strengthened radiation protection. The objective is to meet and integrate the expectations of the wide set of radiation protection stakeholders as best as possible. This partnership also specifically aims to build bridges with research activities carried out at European level in the “non-Euratom” fields, in particular in the health sector.

Beyond these research activities, PIANOFORTE will contribute to maintaining a sustainable capacity of expertise in radiation protection in Europe, which is internationally recognized, in particular by promoting the availability, use and sharing of existing state-of-the-art research infrastructures at the European level as well as by implementing education and training activities.

The partnership will build on previous work, and in particular on the results of the European joint program CONCERT conducted under the H2020 framework program which ended in 2020. It will also benefit from the achievements of other European projects just completed or in progress such as MEDIRAD, HARMONIC, RadoNorm or SINFONIA.

To date, PIANOFORTE involves 58 partners from 22 EU countries as well as the UK and Norway. It mobilizes public partners (public research organizations, authorities in the field of radiation protection, universities) but also the six European research platforms in radiation protection (MELODI, EURADOS, EURAMED, NERIS, ALLIANCE and SHARE). This initial consortium is expected to expand with the entities that will be selected in the framework of the open calls for tenders organized during the partnership.

The partnership will last 5 years and is expected to end in 2027. The estimated budget for PIANOFORTE is 46 million euros, 65% of which will be financed by the European Union and the rest by the partner countries. IRSN is the coordinator of the partnership.

ELKH researchers demonstrate continuous decline of human imagination with age

Under the leadership of Dr Ilona Kovács, director of the ELKH-ELTE-PPKE Adolescent Development Research Group and a university lecturer at the Eötvös Loránd University Faculty of Education and Psychology (ELTE-PPKE ), in an online questionnaire-based study, researches have studied age-related changes in the functioning of the human imagination. They found that from age 12 to 60, the vividness of imagination declines consistently as people get older. The findings indicate that, in addition to the developmental aphantasia – a lack of imagination – that occurs in adulthood, there may also be a genetically based form of aphantasia that can also be observed in childhood. A study presenting the research has been published in the prestigious international journal Cortex.

 Human imagination is perhaps the most subjective mental function, which is why it is difficult to compare the imagination of individuals. The vividness of imagination ranges from aphantasia, i.e. the complete absence of imagination, to hyperphantasia, i.e. a very vivid imagination.

Until now, investigations into the functioning of the imagination have primarily focused on capturing and measuring this subjective phenomenon in some way. Previous research using questionnaires, experiments and brain imaging methods have predominantly studied imagination activity in adults, which meant they did not reveal whether the vividness of imagination characteristic of an individual changes with advancing age, or what transformation imagination goes through during growth.

With the current study, the researchers were curious about the proportion of people living with aphantasia. In an online survey people of different ages were asked to fill out a simple questionnaire (Vividness of Visual Imagery Questionnaire, VVIQ). More than 2,000 respondents between the ages of 12 and 60 completed the questionnaire, which was compiled by the study’s primary author, Erzsébet Gulyás. When filling in the questionnaire the participants had to imagine some simple scenes before evaluating how vividly they were able to recall some details.

Since the sample was not representative it would be difficult to accurately determine the incidence rate of aphantasia based on the present study. However, the researchers observed a surprising and previously unknown negative trend in relation to aging. The study indicates that not only the number of people who have aphantasia, but also the number of people with hyperphantasia varies across different age groups. Based on the negative age trend shown in Figure 1. A), the older someone is, the lower their score is likely to be on the VVIQ questionnaire. Figure B) also shows what percentage of the entire age group people belong to different VVIQ score ranges. It is striking that while 80 percent of adolescents have very vivid imaginations, reporting an imagination of over 60 points on a 100-point scale, and none of them have a level of aphantasia below 20 points, while more than 20 percent of the oldest already belong to the aphantasia group, and just over 20 percent have hyperphantasia.

Figure 1

Based on the results, the researchers depicted the hypothetical development of the human imagination (Figure 2). While most children may fall within the hyperfantasy range, adults have lower imaginative vividness, and more and more people ‘slip’ into the aphantasia range as they age. In addition to developmental aphantasia occurring in adulthood, there may also be a genetically based form of aphantasia that can be observed even in childhood. The new findings have also been noted by the representatives of the world network of people living with aphantasia, and on September 30, 2022, a live online presentation and discussion will take place with the participation of people from all over the world who live with aphantasia.

Figure 2

The survey is still available, you can fill in the VVIQ questionnaire here, and find more information about the research here.

SZTAKI developing artificial intelligence for defense purposes

The ELKH Institute for Computer Science & Control (SZTAKI) is participating in an international project to research self-learning artificial intelligence for defense purposes. The FARADAI project will be implemented over the course of three and a half years with the support of nearly EUR 18.5 million from the European Defense Fund, which aims to increase European defense capabilities in cooperation with 35 organizations from 13 countries. The coordinator of the consortium is the Greek research institute CERTH (The Center for Research & Technology, Hellas). Also participating in the project are the research network Fraunhofer and some member companies of the arms manufacturer Rheinmetall from Germany, along with some member companies of France’s Naval Group and Thales Group.

In the defense industry, there is a growing demand for artificial intelligence (AI) systems that are able to adapt and learn from their environment in a cost-effective, autonomous manner, without supervision or intervention. In the FARADAI project, researchers are further developing existing technologies in the field of artificial intelligence while simultaneously also proposing new, innovative AI solutions in the area of autonomous defense systems.

SZTAKI’s task is to develop both algorithms that continuously learn from a small amount of data along with developing self-explanatory solutions based on self-learning in simulation environments. On the Hungarian side, the project is being managed by András Benczúr, scientific director of the Artificial Intelligence National Laboratory and head of SZTAKI’s Informatics Laboratory, and Roland Tóth, researcher of the National Laboratory for Autonomous Systems and senior scientific associate with SZTAKI’s Systems and Control Lab.

For more information, see the SZTAKI website.

ATK MGI researchers have achieved a significant result in investigating the responses of barley to fungal infection

Led by Klára Mészáros, researchers from the ELKH Centre for Agricultural Research’s Agricultural Institute (ATK MGI) and Plant Protection Institute (ATK NÖVI) have examined the role of antioxidant enzymes, including superoxide dismutase, in response to Pyrenophora infections. Through experiments on barley varieties, ATK researchers became the first to establish that the enzyme activity induced in the early stages of infection shows a tendency to increase as the disease progresses. The results could contribute to a deeper understanding of the physiological processes taking place in plants under biotic stress. The findings from the research were published in the scientific journal Sustainability.

Pyrenophora teres f. teres (PTT) is one of the fungi that infect barley and causes significant damage to these crops both in Hungary and worldwide. The presence of the pathogen causes characteristic longitudinal and transverse necrotic lesions and dead leaf surfaces – known as net blotch – to appear on barley leaves. Due to the reduction of the assimilation surface, this leads to a significant loss in yield. A wide range of resistances to net blotch can be observed among barley varieties, which vary with different isolates of the pathogen.

As a result of the stress caused by the infection, reactive oxygen forms appear in the plant’s cells, which play an important role in the regulation of signaling pathways, various metabolic and developmental processes, but which can also cause oxidative stress in higher concentrations. The balance between the generation of reactive oxygen forms and their removal plays a key role in defending against pathogens. Superoxide dismutase (SOD) is one of the most important antioxidant enzymes involved in the fine-tuning of this process.

The young ATK MGI researcher Viola Kunos and her colleagues conducted greenhouse experiments on five varieties of barley with different resistances, during which the plants were infected with three different PTT isolates. The researchers measured SOD enzyme activity during the early phase of infection (0–3 days) and evaluated leaf symptoms caused by the fungus.

An increase in SOD activity was observed as a result of the fungal infection, the extent of which significantly depended on both the variety of barley and the isolate used to infect it. The increase in SOD activity proves the presence of reactive oxygen species formed in the early stages of infection. Increased SOD activity due to infection promotes the formation of hydrogen peroxide (H2O2), thereby protecting the plant cell from the accumulation of reactive oxygen forms. The researchers found that SOD enzyme activity increased to a greater extent in cultivars susceptible to PTT infection than they did in resistant genotypes.

The results confirm that the sensitivity of barley varieties to different isolates of the fungus varies, which was also reflected in the change in SOD activity. In several cases, a significant correlation was found between the resistance of different youthful barley genotypes and the change in SOD enzyme activity. Based on the results, the measurement of SOD activity can open new perspectives on the detection of early stress reactions induced by PTT. However, the resistance of the different varieties cannot be estimated solely on the basis of SOD enzyme activity.

In order to clarify the role of antioxidant enzymes in plants under biotic stress studying other parts of the antioxidant enzyme system is also necessary, therefore the researchers plan to expand their experiments into this direction.