Joel Ochieng

Dr. Joel Ochieng

orcid

Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
26 October 2013 in BMC Complementary and Alternative Medicine
Verified
Journal Article
Open access
PDF file
TMTrizah K Milugo
Trizah K Milugo
LKLeonidah Kerubo
Leonidah Kerubo
JOJames O Ochanda
James O Ochanda
BOBethwell O Owuor
Bethwell O Owuor
FWFred A Wamunyokoli
Fred A Wamunyokoli
JOJoel Ochieng
Joel Ochieng
Background: The Quinine tree (Rauvolfia caffra) is used as a medicinal plant among traditional communities in many countries to manage tumors and other diseases associated with oxidative stress. To validate indigenous knowledge and possibly position this herb for technology uptake and utilization, we established the level of antioxidant activity in R. caffra, and probed for the presence of associated phytochemicals. Methods: Antioxidant activity was determined on 1,1-diphenyl-2-picrylhydrazyl (DPPH) while major phytochemicals were identified by multiple tests on methanol fractions. Results: R. caffra showed promise as a cure, with antioxidant activity comparable to the commercially used drug quercetin (R. caffra = 79.7% ±1.9; quercetin = 82.6% ± 2.0). However, we found two phytochemicals with possible antagonistic effect: co-occurrence of alkaloids and saponins significantly reduced antioxidant activity (alkaloids only = 63%; alkaloids plus saponins = 15%; steroids, terpenoids and cardiac glycosides = 82%), thus alkaloids and saponins should be exclusive to each other in drug formulations. Conclusions: Antagonistic relationship among phytochemicals would affect the efficacy of crude extracts as used in traditional medicine. Unlike in herbal medicine, use of modern biotechnology in extraction, purification and design of optimal combinations will ensure efficient drug formulations with optimum bioactivity and minimum toxicity. Metabolic pathway engineering under a controlled environment may optimize availability of desired compounds.

1 August 2007 in Molecular Phylogenetics and Evolution
Verified
Journal Article
Closed access
JOJoel Ochieng
Joel Ochieng
Robert HenryRobert Henry
Robert Henry
PBPeter R. Baverstock
Peter R. Baverstock
DSDorothy A. Steane
Dorothy A. Steane
MSMervyn Shepherd
Mervyn Shepherd

25 December 2023 in Conservation Science and Practice
Verified
Journal Article
Open access
LBLaura Bertola
Laura Bertola
ABAnna Brüniche‐Olsen
Anna Brüniche‐Olsen
FKFrancine Kershaw
Francine Kershaw
IRIsa-Rita Russo
Isa-Rita Russo
Anna MacDonaldAnna MacDonald
Anna MacDonald
GSGernot Segelbacher
Gernot Segelbacher
Molecular tools are increasingly applied for assessing and monitoring biodiversity and informing conservation action. While recent developments in genetic and genomic methods provide greater sensitivity in analysis and the capacity to address new questions, they are not equally available to all practitioners: There is considerable bias across institutions and countries in access to technologies, funding, and training. Consequently, in many cases, more accessible traditional genetic data (e.g., microsatellites) are still utilized for making conservation decisions. Conservation approaches need to be pragmatic by tackling clearly defined management questions and using the most appropriate methods available, while maximizing the use of limited resources. Here we present some key questions to consider when applying the molecular toolbox for accessible and actionable conservation management. Finally, we highlight a number of important steps to be addressed in a collaborative way, which can facilitate the broad integration of molecular data into conservation.

1 January 2007 in Genetics and Molecular Biology
Verified
Journal Article
Open access
PDF file
JOJoel Ochieng
Joel Ochieng
DSDorothy A. Steane
Dorothy A. Steane
PLPauline Y. Ladiges
Pauline Y. Ladiges
PBPeter R. Baverstock
Peter R. Baverstock
Robert HenryRobert Henry
Robert Henry
MSMervyn Shepherd
Mervyn Shepherd
The utility of microsatellites (SSRs) in reconstructing phylogenies is largely confined to studies below the genus level, due to the potential of homoplasy resulting from allele size range constraints and poor SSR transferability among divergent taxa. The eucalypt genus Corymbia has been shown to be monophyletic using morphological characters, however, analyses of intergenic spacer sequences have resulted in contradictory hypotheses- showing the genus as either equivocal or paraphyletic. To assess SSR utility in higher order phylogeny in the family Myrtaceae, phylogenetic relationships of the bloodwood eucalypts Corymbia and related genera were investigated using eight polymorphic SSRs. Repeat size variation using the average square and Nei's distance were congruent and showed Corymbia to be a monophyletic group, supporting morphological characters and a recent combination of the internal and external transcribed spacers dataset. SSRs are selectively neutral and provide data at multiple genomic regions, thus may explain why SSRs retained informative phylogenetic signals despite deep divergences. We show that where the problems of size-range constraints, high mutation rates and size homoplasy are addressed, SSRs might resolve problematic phylogenies of taxa that have diverged for as long as three million generations or 30 million years

12 October 2016 in Antioxidants
Verified
Journal Article
Open access
PDF file
LOLillian Oglesby
Lillian Oglesby
AAAnthony Ananga
Anthony Ananga
JOJames Obuya
James Obuya
JOJoel Ochieng
Joel Ochieng
ECErnst Cebert
Ernst Cebert
VTVioleta Tsolova
Violeta Tsolova
The skin color of grape berry is very important in the wine industry. The red color results from the synthesis and accumulation of anthocyanins, which is regulated by transcription factors belonging to the MYB family. The transcription factors that activate the anthocyanin biosynthetic genes have been isolated in model plants. However, the genetic basis of color variation is species-specific and its understanding is relevant in many crop species. This study reports the isolation of MybA1, and MYBCS-1 genes from muscadine grapes for the first time. They are designated as VrMybA1 (GenBank Accession No. KJ513437), and VrMYBCS1 (VrMYB5a) (GenBank Accession No. KJ513438). The findings in this study indicate that, the deduced VrMybA1 and VrMYBCS1 protein structures share extensive sequence similarity with previously characterized plant MYBs, while phylogenetic analysis confirms that they are members of the plant MYB super-family. The expressions of MybA1, and MYBCS1 (VrMYB5a) gene sequences were investigated by quantitative real-time PCR using in vitro cell cultures, and berry skin samples at different developmental stages. Results showed that MybA1, and MYBCS1 genes were up-regulated in the veràison and physiologically mature red berry skins during fruit development, as well as in in vitro red cell cultures. This study also found that in ripening berries, the transcription of VrMybA1, and VrMYBCS1 in the berry skin was positively correlated with anthocyanin accumulation. Therefore, the upregulation of VrMybA1, and VrMYBCS1 results in the accumulation and regulation of anthocyanin biosynthesis in berry development of muscadine grapes. This work greatly enhances the understanding of anthocyanin biosynthesis in muscadine grapes and will facilitate future genetic modification of the antioxidants in V. rotundifolia.

17 October 2009 in Conservation Genetics
Verified
Journal Article
Closed access
PDF file
JOJoel Ochieng
Joel Ochieng
MSMervyn Shepherd
Mervyn Shepherd
PBPeter R. Baverstock
Peter R. Baverstock
GNGarth Nikles
Garth Nikles
DLDavid Lee
David Lee
Robert HenryRobert Henry
Robert Henry