LOS HECHOS DE VIOLENCIA SEXUAL CONTRA LAS MUJERES ATRIBUIDOS

IV . l ) E f fects on Gra in

Wa rdla w ( 1 9 7 0 ) reported a reduct i on in t h e i ndivi du a l gra in weight of wheat cul t ivar Gabo when it received low temperature

( 1 5°C/ 1 0°C ) t re atment during 1 5 - 2 5 days f rom anthe s is c ompa red with

2 1°C / l 6°C and 2 7°C/ 2 2°C t reatment . There wa s interact ion between l ight

intens ity and t empe rature in such a way that the reduct ion in gra in

weight due t o l ow l i ght , wa s greatest at high t emperature . S o f ield et

a l . ( 1 9 7 7 ) and Spiert z ( 1 9 7 7 ) repo rted that the durat ion of grain

g rowth dec re a sed as temperature rose . Also they repo rted that an

inc rease i n t empe rature inc rea sed t he rate of growth per grain . This

was supported by Donovan et al . _{( 1 9 8 3 ) . Wa r rington et a l . ( 1 9 7 7 )}

f ound that wheat plants grown at l o w temperature during e a r

deve l opment h a d more potent i a l l y fert i l e f l o rets i n each spikelet and t hat low t empe rature du ring gra in f i l l ing period ( 2 0°C and l 5°C )

resulted i n heavier individual grains c ompa red t o high temperature ( 2 5°C ) .

Campbe l l a nd Davidson ( 1 97 9 ) f ound that seed set o f p r ima ry and seconda ry f lo rets and seed weight of Manitou wheat were inversely r e lated t o t emperatu re .

IV . 2 ) E f fects on Grain and P reha rvest

Be lde r o k ( 1 9 6 1 ) reported that h igh tempe rature during t he

t ransit ion f rom milk- t o mealy-ripene s s af fected durat ion o f do rmancy o f wheat grains . The h igh t empe rature during this per iod reduced t he a verage durat i o n o f t he dormancy . A l s o Be lderok ( 1 9 6 8 ) reported that hot weathe r du ring t he dough st age of grain deve lopment s ho rten the d ormancy period, whi l e coo l weather extended it . Niel son e t a l .

( 1 9 8 4 ) s t udied t he e f fect o f weather va riables during mat u rat ion on p reharve st sprout ing o f winte � wheat , t hey repo rted that sprouting was i n c reased by l a rge da i ly tempe rature f luctuat ions , low da i l y

t emperatures and high precipitat ion . Reddy e t al . ( 1 9 8 5 ) obse rved that high t emperature during the g r a in f i l l ing pe riod ( 2 6°C ) induced l owe r dormancy level s whereas the l o w tempe rature ( l 5°C ) induced

h igher leve l s of do rmancy . The degree of expres s ion o f t he do rmancy

level depends on the t emperature at which the s eeds a re ge rminated . A

l o w germination tempe rature ( l 5°C ) i s e f fect ive for breaking dormancy

and thus less dormancy is expre s sed . S t rand ( 1 9 8 9 ) a l s o reported the

e f fect of h igh tempe rature and h igh radiation during preharve s t generally reduced seed do rmancy .

Synchrony o f mat u rat ion t ra i t s such a s embryo maturity, embryo dormancy, base a-amy l a se and ge rmina t i ve a-amylase with h a rves t ripeness i n wheat wa s reported t o b e a f fected by genotype and

t emperature regime dur ing the grain development pe riod ( C ro s s , 1 9 7 7 ;

Gordon, 1 9 7 8 ) . Gordon ( 1 97 8 ) found that l a c k o f germinat ion i n the

coo l envi ronmen t was due to emb ryo immaturity rather than do rmancy, a nd this h appened t o a l l the four genotypes of wheat s t udied .

P lett and Larter ( 1 9 8 6 ) experiment ed with one whea t line, RL4 1 3 7 a nd three t rit icale l ines and reported that there existed a n

i nt e raction between ge rminat ion t emperature a n d maturat ion

t empe rature . They concluded that ge rminat ion tests at 2 5°C p roduced

t o l e rance rat ings that consistent ly di f fe rent iated among genotypes ove r a range of stages of kerne l deve lopment as we l l as di f f e rent

t emperatures du ring ke rnel matu ration . But t he ge rminat ion dat a f o r

RL4 1 3 7 wheat s howed t h a t t h e ef fect o f maturat ion tempe rature

mani fested i t s e l f c le a r ly when grain we re ge rminated at 1 7°C . For

t h i s wheat l ine the h ighe r the mat u rat i on tempe rature t he lower the sprout ing s c o re .

V) a-AMYLASE

Def ined a s an e ndo , a- 1 , 4 -glucan 4 glucanohydrolase

( E . C . 3 . 2 . 1 . 1 ) ( Meredith and Jenkins , 1 9 7 3 ) , a-amylase i s a g roup o f enzymes wh ich h a s a n important role i n the breakdown o f cereal endosperm . Three t ypes o f a-amy l a s e in cere a l gra ins have been

reported s o f a r . The f i rst group , a-amy l a se 2 , has been re ferred t o

a s green a-amylase ( Olered and Jons s on , 1 9 7 0 ) , group I I ( Sa rgeant , 19 79J 1 9 8 0 ) , G I and G I I (Ma rchylo e t al . , 1 9 8 0 ) and c a l led I by Daussant et

a l . ( 1 9 8 0 ) . Cha racte ristics of a-amylase 2 a re that i t h a s a broader pH opt imum, greater heat labi l i t i e s , and a h ighe r molec u l a r we ight

compa red t o the second group of a-amylases (Ma rchylo e t a l . , 1 9 7 6 ) .

The isoelect ric points o f a-amy l a s e 2 ranges between 4 . 5 - 5 . 1 (Marchylo e t al . , 1 9 7 6 ; Sargeant , 1 9 8 0 ) . The second group o f a­ amyl a s e s , a-amylase 1 , i s a ma j o r const ituent o f a-amy l a s e in

ge rminated seeds . This group o f a-amylase was known by othe r names

as II or ma l t (Daus sant et al . , 1 9 8 0 ) , group I ( Sargeant , 1 9 8 0 ) and G I I I (Marchylo et a l . , 1 9 8 0 ) . a-amy l a se 1 h a s an isoelect r i c point a round 6 . 0 - 6 . 5 ( Tk achuck and Kruge r , 1 97 4 ; S a rgeant , 1 9 8 0 ) and the pH opt imum f o r enzyme act ivity is between 5 . 5 - 5 . 6 ( T kachuck and Kruger , 1 9 7 4 ) . I t i s only a-amylase 1 t h a t i s able t o absorb onto a nd

s ubsequent l y degrade t he undamaged raw s t a rch granule ( S a rgeant ,

1 9 8 0 ) . Adso rption o f a-amylase t o the sta rch granule i s a

p rerequ i s it e for s t a rch degrada t ion .

Dauss ant et al . ( 1 9 7 9 ) repo rted that there was a t h i rd group o f a-amylase in wheat which they c a l led I I I ( he re referred t o a s a­

amylase 3 ) . This g roup o f enzyme s a re found in deve loping s eeds only, and di f fe r s f rom a-amylase 2 and a-amylase 1 in that it s hows

c athodic migration , when elect ropho re sed at basic pH ( a-amy l a se 1 and a-amy l a s e 2 migrat ing towards t he anode unde r these condit ions) . Daussa nt and Renard ( 1 9 8 7 ) f ound that this t h i rd group o f a-amylase h a s an i s oe lect ric point above 1 0 .

There a re reports that immature ke rnel s o f wheat cont a in h igh leve l s o f a-amylase and the leve l f a l l s rapidly as the g r a ins mature

( Olered and Jonsson, 1 97 0 ; Kruge r , 1 9 7 2 a ; Meredith and Jen k i n s , 1 9 7 3 ; Dedio e t a l . , 1 9 7 5 ; Ma rchylo e t a l . , 1 97 6 ; Daussant e t a l . , 1 9 7 9 ; Ma rchylo e t a l . , 1 9 8 1 ; Daus sant and Renard, 1 9 8 7 ) . The a-amylase level in wheat kerne ls du ring deve l opment reached a maximum l eve l

'

a bout 1 0 - 1 5 days a ft e r anthesis ( Dedio et a l . , 1 9 7 5 ) . The en zyme in a t he imma t u re g rains is found l a rgely in the pe ricarp ( K ruge r , 1 9 72 ;

Meredith a nd Jen k in s , 1 9 7 3 ; Dedio e t al . , 1 9 7 5 ) . S ince t he pe ricarp o f immat u re wheat grains contain mas s ive amount s o f sma l l s t a rch

granule s , i t was postulated that the amylase act ivity i n t he grain at this s t age w a s a s sociated with met abol ism o f the peric a rp s t a rch

( Meredith and Jenk ins , 1 9 7 3 ) . Daus s ant a nd Renard ( 1 9 8 7 ) reported in t he p e r i c a rp o f deve loping wheat kerne l , a-amylase 2 and 3 a re both p resent . The low pi form ( a-amy l a se 2 ) was detected i n t he maternal t issue s , p r i o r to anthe s i s , whe reas a-amylase 3 wa s ident i f ied a t a later s t age , about 1 1 days a fte r anthesis , j ust before t he leve l o f

l ow p i e n z yme wa s a t i t maximum . Upon further development o f the

grain, a-amylase 3 disappeared more rapidly t han a-amy l a se 2 .

An e xpe rimen t by Ma rchylo e t al . ( 1 9 8 1 ) showed t h a t the immature wheat endo spe rm-a leurone ( seed coat and endosperm det a c hed) produced cons iderably less a-amylase act ivity than immature who l e or de­ embryonated wheat kernels . They p roposed that the seed coat may cont a in f a c t o r ( s ) required for n o rma l a-amylase iso zyme synthe s is .

V . 1 ) in G rain o f Wheat

I n t he mature wheat grain ge rminat ive a-amylase appe a rs after 2 days ' imbibi t i on , and steadi ly i n c re a ses in amount with t ime (Kruge r ,

p

1 9 7 2 ) . The s ites o f product ion o f a-amyla se i n germinat ing grains

have been i nvest igated extens ively in barley . I t is gene ra l ly a c cepted that gibbe rel l ic acid produced by the embryo o f germinat ing b a rley a c t s upon the a leu rone t i s sue to induce the de n o vo synthe s i s o f seve r a l hydrolases , inc luding a-amylase ( P a leg, 1 9 6 0 ; Groat and

B riggs , 1 9 6 9 ) .

Varner a nd Chandra ( 1 9 6 4 ) postul a ted that gibbe re l l ic a c id control led t he synthes i s o f a-amy l a s e ( and other heat - s t able p roteins ) in ba rley a leu rone ce l ls by caus ing the production of specif ic mes se nger RNAs . Recent studie s , u s ing cDNA hyb ridi z at ion t e chnique s , have shown that GA3 regul ates t he production of a-amylase mRNA in b a r le y aleurone layers ( Jacobsen and Higgins , 1 9 8 2 ; Chandler

Futhe r , c a lc ium ions have a n import ant role in synthe s i s and / o r secret ion of t he high pi a-amylases ( Jone s a n d Jacobsen, 1 9 8 3 ; Jones and C a rbone l l , 1 9 8 4 ; Deikman and Jones , 1 9 8 6 ) . For inst ant Jones and Jacobsen ( 1 9 8 3 ) reported that the wit hdrawa l of Calcium ions f rom the incubat ion medium of ba rley a leu rone l aye rs reduced t he rate o f

accumu l a t ion o f a-amylase a c t i v i t y i n the medium a fter 5 hours

incuba t ion by 8 5 % relat ive to cont ro l s incubated in t he presence of 1 0 mM CaC12 . The ef fect Ca lc ium ions on the sec ret ion o f a-amylase was l a rge l y on group B a-amy l a se ( a-amy l a se 1 ) .

I n wheat , a leurone layers secreted a-amylase when incubated with GA3 ( Rowsell and Goad, 1 9 6 4b ; La idman e t a l . , 1 9 7 4 ) . Some evidence a ls o suggested that a-amy l a s e may be s ynthe s i zed in the s cutel lum of whea t kernels ( Ma rchylo e t a l . , 1 9 8 0b ; Okamoto et a l . , 1 9 8 0 ) .

Okamo t o e t a l . ( 1 9 8 0 ) us ing the s ubst rate-f i lm technique showed t hat a-amy l a s e in t he ge rminat ing cere a l grain f i rst appea red in the region o f epithe l i a l cells o f the scut e l l um and d i f fused int o the

e ndospe rm t is sue late r . That the embryo / scutel lum produces a-amylase

h a s s ince been con f i rmed by seve r a l worke rs e . g . MacGregor and Mat suo ( 1 9 8 2 ) and Cornford et a l . ( 1 9 8 7 ) . Howeve r the embryo contribute s only a sma l l propo rtion o f a-amy l a se synthe s i zed in the ge rminating ba rley . Groat and Br iggs ( 1 9 6 9 ) repo rted that in bar ley the remova l o f embryo at any t ime after 3 day s germination had no e f fect on the quant ity of en z yme ultimate l y p roduced in the endosperm .

E a s twood e t a l . ( 1 9 6 9 ) repo rted that the a leu rone t i ssue i s o l ated f rom t he qu iescent wheat grain conta ined a cons ide rable quant ity o f a-amy l a s e wh ich i s complet e l y sec reted when the t i s sue i s incubated

in a queous medi a . The addit ion o f either kinet in o r g ibbere l l i c a c id t o t he medium did not sign i f icant l y inc rea se the level o f enzyme act ivit y . But when the aleu rone t i ssue is incubated f i r s t with

kine t in a nd then with gibbe re l l ic acid , there is a two - f o ld increase in s e c reted a-amylase activity . The earlier work by T revener and Laidman ( 1 9 6 8 ) had showed that the extract o f wheat s t a rc h ( endo spe rm) induced the re lease of a-amy lase f rom the a leurone tissue , which has been i s o l a ted as bran f rom the qui e scent wheat gra i n . Th is led

Eastwood e t al . ( 1 9 6 9 ) to conclude that t he starchy endosperm o f wheat seemed to cont a i n a compound which has cyt o kinin activity and which i s respons ible f o r t h e induction o f e s sent i a l met abolic proce sses in t he a leu rone c e l l s .

V I ) ENDOSPERM DEGRADAT ION

The endospe rm of wheat is composed o f ce l l s that cont a in many sta rch granules embedded in a mat ri x o f proteinaceous mat e r i a l

a .

( Bradbury e t al . 1 9 5 6 ) . The s t a rch granu les in wheat consist o f sma l l

sphe r i ca l , B type granules approximately 5 - 8 � i n diameter and la rge lent i c u l a r A type granules approximately 1 5 - 3 0 � in diameter

( Sa rgeant , 1 9 8 0 ) . Eve rs and Lin ley ( 1 9 7 7 ) repo rted that t he sma l l ­ s i ze granules fo rmed mo re than one third o f the total we ight o f sta rch .

D ronzek et a l . ( 1 9 7 2 ) obse rved that a-amylase began i t s attack in t he a leurone l aye r and pre f e rent i a l ly a t t acked la rge lent icu lar granule s . As ge rminat i on proceeded B type granules we re a l s o e roded but at a s lowe r rate than the A type granules . The l a rge granules were att a c ked at the groove and at loca l i z ed s ites on the su rface .

Once the s u r face was eroded, the degradat ion seems to move through the l aye rs o f t he granule t oward the centre . I n sma ll granules the enzyme ente red t he granule at one or t wo s ites and then completely digested

the interior core o f the granule ( D ronzek e t a l . , 1 9 7 2 ) . B type

granu les a re riche r in phospho l ipids than A-type granu les which could account for the i r s lower deg radat ion (Meredith et al . , 1 9 7 8 ) .

F incher and St one ( 1 9 7 4 ) have demonst rated that t he protein mat rix wh ich adhe res to the s t a rch granules in wheat endosperm dis appe a rs a fter one day ' s t rea tment with gibbe re l l ic a c id . This

change , a t t r ibutable to proteolyt ic enzyme s , would inc rease the