Rwanda Journal

A literature review of mammalian research respective to the Akagera ecosystem in Rwanda

2018-04-09T16:51:45+00:00

The Akagera NP (and the Mutara GR) in north-eastern Rwanda are considered part of the most complex and biodiversity rich savannah ecosystem in eastern Africa. Following the violent past of Rwanda, the park has recovered from civil war, poaching and overgrazing, counting today more than 12,000 large mammals. Since proclamation in 1934, a wealth of ecological research was carried in these protected areas. This literature review summarizes the available literature and puts it into a historical context, compiling more than 90 books, book chapters, and journal articles but also unpublished theses and reports respective to the ecology and conservation of mammals.

Keywords: literature review, Akagera ecosystem, conservation history, mammals

Riboflavin induced tolerance against the root-knot nematode Melopidogyne graminicola in rice

2018-04-09T16:51:45+00:00

The role of plant hormones such as Salicylic acid, Jasmonic acid and Ethylene in plant defense has been largely investigated particularly in dicotyledonous plants. Riboflavin has also shown effects on plant physiology but its role in plant defense/tolerance is yet to be elucidated.

Rice plantlets were randomly grown in laboratory, sprayed with hormones and riboflavin 24 hours before their infection by the nematodes meloidogyne gramicola juvenile 2. Two types of infection experiments were done. The normal rice nipponbare susceptible to M. gramincola infection was used in the first while in the second series experiments four transgenics/mutants were used. The shoots length, roots length and the roots weight were measured. The numbers of galls per plant were counted under a stereomicroscope. The relative expression of the genes Osein2b, Oswrky 45, OsJAmyb and OsNPR1 was evaluated using the qRT-PCR method.

It was noticed that the plantlets treated with BTH significantly developed less galls compared to control (P = 0.000<0.05). This was also observed with ETHEPHON and MeJA spray (P =0.001 and P = 0.000 <0.005 respectively). The treatment with riboflavin didn’t show a significant effect (P = 0.61>0.05) in comparison with the control. However these plants grew taller enough with a strong roots system except for OsNPR1antisense line which developed more galls than others tested plants.

The foliar supply of riboflavin on rice significantly upregulated OsNPR1 in leaves and roots of rice plantlets. OsWRKY45 was also upregulated in both leaves and root samples.

Keywords: Riboflavin, systemic tolerance, transgenics/mutants, gene expression

Volatile aroma compounds and sensory characteristics of traditional banana wine “Urwagwa” of Rwanda

2018-04-09T16:51:45+00:00

Urwagwa, produced mainly from the fermentation of banana juice, is the oldest and popular Rwandan traditional alcoholic beverage. In the present paper, the aroma profiles of Urwagwa wine samples collected from the districts of Rulindo and Ngoma were investigated. Headspace/ Solid-Phase Micro Extraction (HS- SPME) and gas chromatography - mass spectrometry (GC/MS) were applied for the analysis of volatile aroma compounds. Odour Active Values (OAVs) and sensory analysis were also performed to define the aromatic profile of Urwagwa wine. The findings showed that the aroma profiles of two types of Urwagwa wines analyzed were not significantly different. Forty eight volatile aroma compounds, including esters, higher alcohols, acids, terpenes, furan and phenol were identified and quantified in Urwagwa wines. Among them, ethyl caprylate, ethyl caproate, ethyl caprate, ethyl acetate, isoamyl acetate, ethyl acetate, ethyl butyrate, phenethyl acetate, phenethy alcohol, caprylic acid, 1-octanol and isovaleric acid exhibited OAVs ˃ 1, and are considered as the major contributors of aromatic character of Urwagwa wine; described as fruity, floral, banana, sweet and fatty notes. However, the overall aroma profiles of the investigated Urwagwa wines were dominated by the fruity note due to the high amount of ethyl caprylate, ethyl caprate and ethyl caproate in this Rwandan traditional banana wine.

Keywords: Aroma compounds; Sensory analysis; Banana wine, Urwagwa