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Mutation breeding for in planta modification of amylose starch in cassava (Manihot esculenta, Crantz)
No full textCassava provides more dietary energy per unit area than any staple crop but native cassava starch has limited food and industrial applications. Different transgenic biotechnology approaches and ex situ physical and chemical starch modifications have been used to obtain desirable traits suitable for various food applications. But consumers are skeptical about the safety of the genetically modified foods and chemical residues. To meet the demand, gamma irradiation (this is energetic electromagnetic wave) which does not leave any residue, was used as a tool to induce in planta variation in amylose production. The four highest amylose producing plants N441P54 (32.7%), N223P12 (31.1%), N373P2 (27.2%), N329P11 (26.8%) and four lowest amylose producing plants N96P16 (14.0%), N353P6 (13.9%), N166P2 (13.2%), N476 P22 (11.7%) observed in the M1V2 generation were found to be significantly different from any one of the four controls HO008 (19.7%), HO001 (22.0%), UCC090 (22.6 %) and UCC026 (20.9%). Mutation is uncontrollable and could also lead to unexpected useful mutants. From this study four unexpected putative free-sugar mutants were identified, which could be used for bioethanol and glucose syrups production; two exceptional deep fissured and flaky mutants for the food industry; seven mutants with transition from A- to C-types of X-ray diffraction patterns with very high levels of crystallinity indexes suitable for replacing acid modified starches in pressing tablets in the pharmaceutical industries were discovered. Based on DSC classification, three gelatinization categories were observed. These were plants without gelatinization transition, plants with gelatinization transition and plants with merged gelatinization and melting transitions, occurring within gelatinization zone during calorimetric scanning from 25 – 110°C. The first and third categories included most of the putative mutants described in the research chapters and they were suitable for shortening the starch processing time required in most commercial starch applications in industry
The proteolytic activity in raw milk and the effect of such activity on the stability of milk proteins
No full textEnglish: Milk flocculation/age gelation is regarded as a major problem for the dairy industry since it has a
negative impact on milk quality. Flocculation can be observed as a physical change in fresh milk
when milk is exposed to extreme destabilisation conditions such as low storage temperatures and
heat exposure (milk added to boiling water during coffee preparation). The end result is decreased
fluidity and increased viscosity due to the formation of a three-dimensional protein network and the
formation of visible flakes. This type of milk is totally rejected by the consumers.
Flocculation can occur through chemical or enzymatic action. The chemical mechanism is when the
three-dimensional protein network is formed during the storage of milk by the interaction between β-
LG and К-casein within the casein micelle due to heat treatment which eventually results in the
formation of a gel. During this interaction, a complex is formed between β-LG and К-casein. The
enzymatic mechanism involves proteases which are responsible for the release of this βК-complex
which forms a protein network and eventually results in the formation of a gel. The two main
enzymes that play a role in milk flocculation are native plasmin and proteases from psychrotrophic
bacteria.
Detection methods for milk flocculation are needed in order to establish the cause and possibly
combat this problem. The already established milk flocculation detection techniques are the Alizarol
test and the protease assay. The techniques developed in this study to detect milk flocculation/age
gelation included RP-HPLC (MILQC software) and the milk agar plate technique for protease
detection. All the techniques can effectively detect high risk milk prone to flocculation/gelation and
some of the techniques can even distinguish between the proteolytic action of indigenous plasmin
and microbial proteases.Afrikaans: Melk flokkulasie/ouderdomsgelering is huidiglik 'n groot probleem vir die suiwel industrie aangesien
dit 'n negatiewe impak het op die kwaliteit van melk. Flokkulasie is die fisiese verandering wat
plaasvind in melk as gevolg van blootstelling aan ekstreme destabilisasie toestande soos lae
opbergings temperature en blootstelling aan hitte (melk wat by kookwater gevoeg word tydens
bereiding van koffie). Die eind resultaat is die afname in vloeistof en terselfde tyd „n toename in
viskositeit wat gevolglik lei tot die vorming van 'n drie-dimensionele proteïen netwerk. Dit lei daartoe
dat melk flokkies bevat wat verbruikers onaanvaarbaar vind en verwerp.
Flokkulasie kan deur middel van chemiese- of ensiematiese aksie plaasvind. Die chemiese aksie word
toegeskryf daartoe dat die drie-dimensionele proteïen netwerk gevorm word as gevolg van interaksies
wat plaasvind (tussen β-LG en К-kaseïen) tydens die opberging van melk. Die interaksies vind binne
die kaseïen missel plaas as gevolg van hitte behandelings wat op melk uitgevoer word. Tydens
hierdie interakies word 'n kompleks gevorm tussen β-LG en К-kaseïen. Die ensiematiese aksie behels
die vrystelling van hierdie kompleks wat gevolglik lei tot die vorming van 'n gel. Proteases van
mikrobiese oorsprong is hiervoor verantwoordelik. Daar is hoofsaaklik twee ensieme wat 'n rol speel
by melk flokkulasie, naamlik plasmien en bakterieë van 'n psigotrofiese oorsprong.
Opsporings metodes vir melk flokkulasie is noodsaaklik om ten einde die oorsaak te kan bepaal en
moontlik 'n oplossing te vind vir die probleem. Tegnieke wat reeds ontwikkel is vir die opsporing van
melk flokkulasie is die Alizarol toets en die protease toets. Die tegnieke wat ontwikkel is met die doel
om flokkulasie/gelering te bepaal sluit die RP-HPLC (MILQC sagteware) en die melk agar plaat tegniek
vir protease bepaling in. Al die bogenoemde tegnieke kan hoë risiko melk wat geneig is tot
flokkulasie/gelering effektief aandui en sommige van die tegnieke kan selfs 'n onderskeid tref tussen
plasmien en mikrobiese protease.National Research Foundation (NRF
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The milk and serum NMR-based metabolic profiles of the South African giraffe (Giraffa camelopardalis giraffa) and their relation to other milk nutrients
No full textThere is little information available on the milk nutrients of wild mammals and none on their milk and serum metabolomes. The giraffe is the largest ruminant and this study compares the information obtained from giraffe with the most common domesticated ruminant, the cow. This is because a lot of information on the cow is available in literature. What makes this study interesting is that the pregnancy status of the female giraffes could be investigated as a variable. The giraffe is one of very few species that can fall pregnant while simultaneously caring for a calf. The current study is part of a larger project regarding behaviour, ecology and biology of giraffes in the Rooipoort Nature Reserve near Kimberley in the Northern Cape. Giraffes were sedated to fit radio transmitters in 2017, and again in 2018 for the removal. Simultaneously, biological samples were collected, inter alia blood and milk. Blood and milk was collected from eleven female giraffes and blood from nine male giraffes. Blood and milk was also obtained from two females in the Sandveld Nature Reserve, Hoopstad district, Free State Province. The metabolites in serum and milk were analysed by Nuclear Magnetic Resonance (NMR) spectroscopy and the milk nutrients (proteins, carbohydrates, fats and fatty acids, and minerals) were analysed according to standard procedures. This study presents a baseline metabolome of serum and milk for giraffes. The results showed differences in serum metabolite concentrations between the 2017 and 2018 samples which could be due to a variation in rainfall and the related availability of browse at the time of collection. The 2018 giraffe group milk metabolite concentrations, particularly lactose, suggest that they were on a lower plain of nutrition when compared to the 2017 giraffe group. The results showed a variation in milk nutrient concentrations between giraffes of different locations and this may be due to different browse being available at these locations because the nutrient content of the browse influences the milk nutrient concentrations. Statistical analysis of milk and serum metabolites showed the greatest differences were between the years of sampling rather than pregnancy status. Pregnancy status was not a significant contribution to the differences in milk nutrients and metabolites. A correlation analysis was used to evaluate the relationship between serum and milk metabolites of female giraffes and their milk nutrients. Milk metabolites were more strongly correlated with milk nutrients than serum metabolites. The serum amino acids isoleucine and valine were positively correlated with milk total protein and casein protein. The milk metabolites alanine, isoleucine, leucine, phenylalanine, and valine were positively correlated with milk whey protein. The serum amino acids isoleucine, leucine, phenylalanine, tyrosine, and valine are all negatively correlated with milk lactose. The concentrations of these amino acids are higher for the 2018 group and the milk lactose concentration is lower for the 2018 group. The lower energy intake for the 2018 group is responsible for the lower lactose concentration and this is correlated with the higher concentrations of serum amino acids because serum amino acids, specifically branched chain amino acids increase in concentrations during starvation. Diet is likely responsible for the positive correlations of milk creatine and creatinine with calcium, iron, lactose, butyric acid, caproic acid, and linoleic acid. Diet affects the concentrations of metabolites and nutrients in milk. Milk citric acid cycle metabolites are positively correlated with lactose. A more energy dense diet, as proposed for the 2017 giraffe group, would lead to an increase in glucose production making more glucose available for lactose production as well as more glucose available to enter the citric acid cycle.National Research Foundation (NRF)University of the Free Stat
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Antigenic properties of snake venom cardiotoxins
Get PDFPhD (Biochemistry), North-West University, Potchefstroom CampusIn this dissertation an innitial investigation was
made to lo~ate antigenic determinants of
cardiotoxin vll 1 from N.nivea with a future view
of applying the knowledge obtained in the design
of synthetic vaccines. The conformation and
surface properties of this toxin differs from that
of proteins of which the immunological properties
are known, so that this information cannot be
directly applied.Parallel to the investigation of
the cardiotoxin, a similar study was carried out
on bovine phospholipase A2 , which was used as
control in the experimental work. Peptides derived
from the sequences of N. nivea vII1 and bovine
phospholipase A2 , were synthesized chemically. The
conformation of these peptides in various
solvents, was determined by circular dichroism
spectroscopy, for relating immunological
properties to epitope structure. Antiserum was
raised against the two proteins, and the
reactivity thereof towards the synthetic peptides
determined. ...Doctora
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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