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Natural Sciences

Mak Scientists Unveil New Method of Measuring Stress Levels in Plants



Just like animals and human beings, plants too can be stressed. Whereas one may easily detect stress in animals and humans basing on their behavior, plant “behavior” is not easy to interpret.  

Why should we be concerned about stress in plants?

Plants under stress cannot reproduce or grow well because they have to divert much of their physiological energy to fighting stress. If the plants are critical food crops, this will lead to perpetual food shortages because their energy resources are spent fighting stress.

New study on measuring stress in plants

A new study titled “Sandwich Enzyme-Linked Immunosorbent Assay for Quantification of Callose” and led by a team of scientists at the Department of Plant Sciences, Microbiology and Biotechnology at Makerere University in collaboration with the University of California, Davis, USA, shows how stress in plants can be measured. According to Prof. Arthur Tugume, the lead scientist of this study and expert in plant diseases, when plants are stressed, they produce numerous molecules within their cells mostly as means of adapting to stress or avoiding the impact of stress. “For example, plants produce reactive oxygen species like hydrogen peroxide, superoxide ions, and hydroxyl ions. These reactive oxygen species are produced rapidly and act as rapid messengers in the plant tissues to activate additional responses spreading over the entire plant body. This helps the plant to withstand or avoid the impact of stress”.

Some of the plants used in the study to design a new method of measuring stress as induced by the bacterium Xanthomonas campestris pv. Musacearum The plants in plate (A) are before infecting them with the bacterium, while in plant (B) are the same plants 14 days after infecting them with the bacterium. Photos by Mr. Abubakar S. Mustafa.
Some of the plants used in the study to design a new method of measuring stress as induced by the bacterium Xanthomonas campestris pv. Musacearum The plants in plate (A) are before infecting them with the bacterium, while in plant (B) are the same plants 14 days after infecting them with the bacterium. Photos by Mr. Abubakar S. Mustafa.

Dr. Ssenku E. Jamilu, a plant physiology expert on the team explains that in plants, stress can be induced by many factors such as pollution in the soil and atmosphere, high soil salinity (salt stress), excessive lack of water (drought), extreme temperatures, lack of oxygen (anoxia), excess radiation, mechanical injury by wounding or by pests that feed on the plants, and infestation by disease-causing microorganisms (pathogens). “Such factors are worsened by climate change, implying the importance of measuring their impact on individual plants to guide plant breeding programmes to ensure sustainable food production in the face of climate change”.

The research indicates that reactive oxygen species set in motion additional processes to ensure limited impact of stress on the plant. For example, a unique carbohydrate, named “callose” starts to accumulate in large quantities within plant cells as a means of fortifying plant cells. Callose differs from the other usual plant carbohydrates such as starch or cellulose because of the way its structures are formed. Also, the production of callose gets increased during stress. Callose acts as a road-block to any pathogen such as bacteria by limiting bacterial movement that would otherwise ease attack on other tissues or cells.

 “If we can artificially induce the stress on the plant, and then measure the amount of reactive oxygen species or callose or any other responses in the plant, we should be able to directly and quantitatively measure the stress,” Prof. Tugume explains.

He however notes that callose participates in many other normal developmental processes of plants and for that reason, there is always some “housekeeping” callose in the plant tissues even without stress. “This means that one must be able to accurately and quantitatively distinguish between ‘stress-induced’ and normal ‘housekeeping’ callose”.

In this study, the researchers used young (2.5-months old) banana plantlets that had been generated from tissue culture at Kawanda Agricultural Research Institute. They then infected the plantlets with a bacterium called Xanthomonas campestris pv. musacearum. This bacterium induces so much stress on the banana plants resulting into a destructive disease known as banana xanthomonas wilt (BXW), the most destructive disease of bananas in East and Central Africa.

The banana leaves, pseudostems and corms were analyzed for callose and compared with the control plants that had been inoculated with water instead of bacteria. The analysis was done using a method called S-ELISA (Sandwich Enzyme-linked immunosorbent Assay), that was designed by scientists in this study. This method is specific to callose.

Callose-specific primary antibodies were used to coat the wells of 96-well microplates followed by incubation with callose extracts from tissues of stressed plants. Additional incubation with same primary callose-specific antibodies was done, and finally, incubation with a secondary antibody that is conjugated to an enzyme. When a substrate is supplied to the enzyme, colour changes were monitored. The presence of callose (and thus stress on the plants) was assessed quantitatively by measuring the intensity of color change resulting from enzymatic action on the substrate. This method proved effective in comparison to the gold standard method of detecting and quantifying aniline blue stained callose using fluorescence microscopy.

This research was part of the PhD studies for Mr. Abubakar S. Mustafa at Makerere University and University of California, Davis. According to Mr. Mustafa, his method is new and can be applied to any plant that is subjected to any stress because generally, plants produce callose in response to stress.” Mr. Mustafa further states that the method is convenient because, if necessary, samples can be processed between a few hours to one year (or even longer), which allows exchange of materials between laboratories and countries when needed, something that was not possible before. The S-ELISA method used 96-well plates which allows high throughout studies, hence, hundreds of samples can be analyzed simultaneously within a few days.

This study has been published as a Protocol by Multidisciplinary Publishing Institute (MDPI) in an open access journal, “Methods and Protocols”, in the section: Biochemical and Chemical Analysis & Synthesis and is freely accessible on

The research was funded by the Bill and Melinda Gates Foundation through the National Agricultural Research Organization (NARO), Uganda. The project had partners including the International Institute of Tropical Agriculture, the Alliance for Bioversity International and International Centre for Tropical Agriculture (CIAT) and CABI.

For more details, contact;

  1. Prof. Arthur Tugume, Lead Scientist of the study, College of Natural Sciences, Makerere University, Email:, Tel: +256772514841
  2. Mr. Abubakar S. Mustafa, Co-Author and PhD student on the study, Email:, Tel: +256702813233
  3. Hasifa Kabejja, Principal Communication Officer, College of Natural Sciences, Makerere University, Email:, Tel: +256774904211

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Natural Sciences

Two Nutrifish-sponsored PhD students win awards of best oral presentations at ICAFA



NutriFish team at the ICAFA conference held from 1st to 3rd September, 2022 in Jinja, Uganda. L-R: Dr. Winnie Nkalubo, PhD Students Julliet Nafula Ogubi and Herbert Nakiyende, Dr. Margaret Masette and Dr. Jackson Efitre (NutriFish PI).

Two of the NutriFish-sponsored PhD students, Nakiyende Herbert and Julliet Nafula Ogubi won the awards for the best and second-best oral presentations in the young scientists’ category at the International Conference on Artisanal Fisheries and Aquaculture (ICAFA) held in Jinja, Uganda from 1st-3rd September 2022.  The conference was organized under the theme “Breaking new grounds to recognize and celebrate the contribution of small-scale fisheries towards food security and nutrition”.   

Julliet Nafula Ogubi (L) and Herbert Nakiyende (R) with their awards at the conference.
Julliet Nafula Ogubi (L) and Herbert Nakiyende (R) with their awards at the conference.

Supported by the International Research Development Centre (IDRC) and the Australian Centre for International Agricultural Research (ACIAR) through their joint programme, Cultivate Africa’s Future Fund (CultiAF), NutriFish aims to address the nutritional needs of vulnerable groups that cannot afford expensive commercial fish but are in critical need of high quality nutritious diets. The Project is coordinated by Dr. Jackson Efitre, Senior Lecturer in the Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences (CoNAS), Makerere University.

Dr. Jackson Efitre (NuriFish PI) with Herbert Nakiyende.
Dr. Jackson Efitre (NuriFish PI) with Herbert Nakiyende.

The title for Nakiyende Herbert’s presentation was: “Are small pelagic fisheries a blessing or curse? Understanding fisher community perceptions towards light fishing on Lake Albert, Uganda”.

Light fishing, the technique of catching fish by light attraction was introduced to Lake Albert, Uganda around early 2000s, to target two small pelagic species (SPS), Engraulicypris bredoi (muziri) and Brycinus nurse (ragoogi). The introduction of light fishing coincided with a period when stocks of large-bodied fishes, such as Tilapia spp, Lates niloticus, Bagras bajad, Alestes baremose, and Hydrocynus forskahlii in the Ugandan waters of Lake Albert had started to decline. Although Lake Albert is shared by Uganda and the Democratic Republic of Congo (DRC), light fishing is prohibited in DRC waters. This study evaluated socio-ecological consequences of light fishing on the fisheries and lakeside communities of Lake Albert in Uganda, to inform sustainable management. Data was collected in April 2021 from three landing sites (Ntoroko, Kaiso, and Dei), through semi-structured interviews and focus group discussions. Light fishing has transformed the lake’s annual fish catch from < 60,000 tonnes (t) in early 2000s, mainly of large species to about 330,000 t, dominated by SPS (60 – 80%) by 2021. The SPS light fishery currently engages over 30% of total fishing boats and 60% of fishers in the Ugandan waters of the lake. The technique has also led to conflicts with fishers targeting the large-bodied species, the main concerns being: i) excessive light fishing effort; ii) competition for fishing grounds; iii) high by-catch (~10%) dominated by juveniles of the large species; and iv) destruction of passive fishing gears used in the large-bodied species fisheries. To ensure co-existence in the multi-species fishery and continued livelihood benefits (employment, income, and food) of the SPS light fishery, resting and closed periods and light-fishery effort control were proposed by 95.4% of respondents. Detailed scientific investigation of the light fishing methods is recommended, to guide on the proposed closed season and fishing effort controls.

Julliet Nafula Ogubi with her award at ICAFA.
Julliet Nafula Ogubi with her award at ICAFA.

Julliet Nafula Ogubi’s presentation was on: “Spoilage mechanisms and associated drivers in post-harvest loss management in freshwater small pelagic fishes in Africa”.

Small pelagic fishes (SPFs) are steadily being recognized for their contribution to livelihoods, food and nutritional security especially in developing countries. The SPFs are schooling fishes with a total length of 20 cm, preserved mainly by open sun-drying.  Despite the bulk harvests, post-harvest losses associated with spoilage continue to hamper their availability, accessibility and consumption. A review of available literature on similar marine species revealed that spoilage commences immediately after harvest and progresses through three cascading but overlapping processes: autolytic (enzymatic), microbial and chemical reactions causing physical, quality, nutritional and economic losses. Spoilage in SPF is accelerated by i) their large surface to volume ratio; ii) the reliance on fluctuating sun radiation for drying which depends on prevailing weather condition; c) limited drying spaces for large quantities landed.  With regard to magnitude of losses, spoilage-related quality deterioration and nutritional changes in fish are rarely evaluated, hence associated economic value is lacking. The magnitude of losses attributed directly to the spoilage mechanisms have not been determined in freshwater SPFs, yet cost-effective interventions target significant processes. Handling practices, especially stacking and mixing of different fish hauls as drivers of spoilage mechanisms have not also been evaluated.  In addition, the effect of prolonged trips and lack of controlled temperature on-board, are less understood. Therefore, an urgent in-depth assessment of quality and nutritional losses and the associated economic value; the contribution of each spoilage mechanism to the magnitude of losses and the effect of handling practices on the rate of spoilage among freshwater SPFs is needed.


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Natural Sciences

Dr. Perpetra Akite wins British Ecological Society Marsh Award for Ecologists in Africa



Dr. Perpetra Akite, College of Natural Sciences (CoNAS), Makerere University.

Dr. Perpetra Akite has been awarded the Marsh Award for Ecologists in Africa.  This prize aims to celebrate the significant scientific achievements of African ecologists and raise their profile in the UK. It is provided by the Marsh Charitable Trust and administered by the British Ecological Society.

Dr. Akite is one of Uganda’s leading entomologists and experts in butterflies. She has made important advances in improving knowledge around insects in Uganda, contributing to assessing and mapping key ecologically sensitive species in the country. She has even had a moth named after her.  

Dr. Akite is also passionate about passing on her knowledge to younger generations and takes part in a great deal of outreach activities at both school and university level. Her goal is to encourage more young people – especially African girls – to begin a career in science.

The winners will be presented with their prizes during a ceremony held at the BES Annual Meeting which runs from 18th – 21st December in Edinburgh. The meeting will bring together over 1000 ecologists (in person and online) to discuss the latest advances in ecological research across the whole discipline.

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Natural Sciences

PESCA Call For Applications: Short Courses Training in Aquaculture



Stakeholders follow proceedings during the Makerere and PESCA-NARO/ARDC Kajjansi workshop held from 19th to 22nd July 2022 at MUZARDI. Researchers met to review and harmonize aquaculture training modules of the EU-supported project.




The Department of Zoology, Entomology, and Fisheries Sciences, College of Natural Sciences, Makerere University was awarded a contract under the European Union-funded PESCA project implemented by Ministry of Agriculture, Animal Industry and Fisheries (MAAIF) for the provision of training services. The overall objective of the assignment is to support training that will improve knowledge, skills, and practices that enhance aquaculture production and productivity in Uganda. This will be achieved through the following specific objectives:

  1. Support the placement of undergraduate students to work (internships) with fish farmers or other suitable aquaculture value chain (AVC) actors;
  2. Conduct inclusive customized short-term training with gender considerations (women, men, youth, people with disabilities) including farmers, Producer Organizations (POs), feed & seed producers, service providers, and other aquaculture stakeholders; and
  3. Support MSc. research and training.

The expected outputs from the short-course trainings are:

  1. Trainees (farmers, Producer Organizations, feed & seed producers, service providers etc.) with job-demanded competency skills & knowledge;
  2. Increased engagement of AVC actors in the training of students & review of university curricula;
  3. Orientation of tertiary Fisheries and aquaculture training institutions’ curricula to practical thematic areas; and
  4. Compendium of different modules compiled and shared with partners.

A certificate of attendance will be issued to trainees who successfully complete the training.


Applications are invited for 180 fully funded bursaries for six (6) trainings covering relevant modules specified in (C) below. Each course is expected to be conducted within seven (7) days jointly with the Aquaculture Research and Development Center (ARDC), Kajjansi, National Fisheries Resources Research Institute (NAFIRRI).


1.Hatchery operators and managersIntroduction to commercial aquaculture; Fish seed production and hatchery management (including fingerling transportation; early stock management in grow-out pond); Fish diseases and health management; Aquaculture business planning and organisation.9th-14th October 2022
2.Fish farmers and farm managersIntroduction to commercial aquaculture; Establishing a commercially viable aquaculture enterprise; Aquaculture business planning and organisation; Aquaculture production systems.23rd-28th October 2022
3. Producer groupsIntroduction to commercial aquaculture; Aquaculture production systems; Fish diseases and health management; Aquaculture business planning and organisation (including group dynamics, resource mobilisation for group self-sustenance; fish marketing skills).6th-11th November 2022
4. Feed producersIntroduction to commercial aquaculture; Fish feeds production; Fish feeding and feed management; Aquaculture business planning and organisation13th-18th November 2022
5. Aquaculture Extension workersIntroduction to commercial aquaculture; Aquaculture production systems, Fish diseases and health management; Aquaculture business planning and organization; Aquaculture Extension workers (including service delivery; aquaculture extension methods and tools).7th November – 2nd December 2022
6. Food and Fish ProcessorsIntroduction to commercial aquaculture; Value addition for farmed fish; Aquaculture business planning and organisation.11th-16th December 2022


Target groupsSelection requirements for admission
Hatchery operators and managersAbility to read and write
Fish farmers and farm managersAbility to read and write
Producer groupsAbility to read, write and presentation of a registration certificate as a CBO or cooperative society
Feed producersAbility to read and write
Aquaculture Extension workersMinimum is a certificate in Fisheries and aquaculture
Food and Fish ProcessorsAbility to read and write


Application form should be electronically filled and submitted here: In addition, a signed recommendation from your District Fisheries Officer or Leader of Producer Organisation should also be sent to the Head of Department (, with a copy to the Team Leader, Dr. Jackson Efitre (, and the short courses Coordinators, Juliet Nattabi Kattabi ( and Rosemary Nalwanga ( by the deadline of 30th September, 2022 at 5:00PM.

The advert is linked below.

Mak_PESCA Short Courses_ZEFs_CoNAS Advert.pdf

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