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EFFECTS OF
ETHYLENE ON SOME SUBMERGENCE-TOLERANT AND SUSCEPTIBLE RICE (ORYZA
SATIVA L.) VARIETIES OF BANGLADESH.
Muktadir Shahid HOSSAIN1, M. Aftab UDDIN1, A.Rashid GOMOSTA2
and M. Anwar HOSSAIN1*
1Department of Biochemistry, University of Dhaka, Dhaka -1000, Bangladesh.
2Department of Plant Physiology, Bangladesh Rice Research Institute
(BRRI), Gazipur-1701, Bangladesh.
Author for correspondence :
(FAX : 880-2-865583, E-mail : anwarh@udhaka.net)
Abstract
Ethylene, a gaseous phytohormone, accumulates in submerged rice
plants causing rapid elongation which results in lodging once the
flood-water recedes. Complete submergence of rice plants under water
for 10 days in presence of an ethylene-biosynthetic inhibitor, aminooxy
acetic acid (AOA), resulted in appreciable lowering of lodging during
post-submergence period when compared with plants submerged without
AOA. It was found that, in general, both ethylene production and height
elongation were higher in submergence-susceptible varieties than in
tolerant ones. Tolerant varieties also formed less ethylene when chilled
at 4 C than susceptible ones. Treatments of excised leaves with exogenous
ethylene caused destruction of chlorophyll and this effect was more
pronounced in susceptible varieties than in tolerant ones. Germinating
seeds of a susceptible variety BR5 responded to exogenous ethylene
by showing increased elongation of first leaf with increasing concentration
of ethylene whereas a tolerant variety FR13A showed almost no response.
All these findings suggest that susceptible varieties not only produce
more ethylene under stress conditions but also respond more pronouncedly
to the phytohormone than tolerant varieties.
Key words : 1-Aminocyclopropane-1-carboxylic acid (ACC)
- Aminooxy acetic acid (AOA) - chilling-chlorophyll-ethylene- gibberellic
acid (GA) - germination-lodging - submergence.
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PARTIAL PURIFICATION AND CHARACTERIZATION OF AN IMMUNOREACTIVE FORM
OF DIHYDROFOLATE REDUCTASE FROM HUMAN LEUKEMIA CELLS
M. Perwaiz IQBAL*, Naseema MEHBOOBALI and Fakhara SULTANA
Department of Biochemistry, The Aga Khan University, Karachi-74800,
Pakistan
* Corresponding author
M. Perwaiz Iqbal,
Department of Biochemistry,
The Aga Khan University,
P. O. Box 3500,
Stadium Road,
Karachi-74800,
Pakistan.
Tel. 92-21-493-0051 Ext. 4463,
Fax 92-21-493-4294
E-mail: perwaiz.iqbal@aku.edu
Running title: Immunoreactive forms of dihydrofolate reductase
Abstract
Immunoreactive forms of dihydrofolate reductase, which do not appear
to have the enzymatic activity nor the ability to bind methotrexate
have been partially purified using affinity chromatography from leukocytes
of a cancer-patient suffering from acute myelogenous leukemia. These
appear to be heterogeneous proteins with apparent molecular weights
543278, 44000 and 19023 as determined by gel-filtration chromatography.
Heterogeneity of the proteins were further confirmed by western immunoblotting.
Upon isoelectric focusing, these separated into four immunoreactive
proteins with isoelectric points 8.1, 6.6, 6.0 and 5.7. These proteins
may be precursors of the active dihydrofolate reductase.
Key words: Dihydrofolate reductase, immunoreactive forms, human leukemia
cells, purification, characterization, multiple molecular forms.
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PURIFICATION AND CHARACTERIZATION OF ENDOGLUCANASE (1,
4-BETA-D-GLUCAN, GLUCANHYDROLASE) FROM MICROCEROTERMES SP.
Nilufer Jesmin KHAN, M. Aftab UDDIN and Sharif AKHTERUZZAMAN
Department of Biochemistry, University of Dhaka, Dhaka-1000, Bangladesh.
Corresponding author : Dr. Sharif Akhteruzzman
Associate Professor,
Department of Biochemistry,
University of Dhaka
Tel: 9661900-59/6113
Email: sharif_az@hotmail.com
Abstract
An endoglucanase (1,4-beta-D-glucan, glucanhydrolase) was purified
from crude extract of Microcerotermes sp. The enzyme was purified
gel filtration on Sephadex G-100 followed by DEAE-anion exchange chromatography.
The 22-fold purified enzyme had a specific activity of 0.70 U/mg protein
with CM-cellulose as substrate. The optimum pH and temperature of
the enzyme were pH 6.0 and 40oC respectively. The enzyme was strongly
inhibited by Hg2+, Fe3+ and Cu2+ and moderately by Mn2+, Co2+, Ca2+
and Zn2+. The Km and Vmax values for CM-cellulose were 1.5 mg/mL and
111 nmol/min/mg. Non-SDS PAGE of both the gel filtration and ion exchange
chromatography fractions showed that the activity corresponded to
a band of around 40 kDa, and this was further confirmed by staining
the 40 KDa band for enzyme activity on PAGE as well as after electroelution.
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Key words: Cellulase, termite, crude extract, chromatography
IMPAIRED NEUTROPHIL FUNCTION IN DIABETES MELLITUS
Laila N. Islam*, K. Saiful Islam, M. Enamul Kabir, M. Sazzad
Hossain, A.H.M. Nurun Nabi and N.G. Banik**
Department of Biochemistry, University of Dhaka, Dhaka-1000, Bangladesh.
Running title : Neutrophils functions in diabetes mellitus
Key words : diabetes, neutrophil phagocytosis, FMLP polarization,
E. coli killing, NBT reduction
*Author for correspondence :
Prof. Laila N. Islam,
Department of Biochemistry ,
University of Dhaka,
Dhaka-1000, Bangladesh
Fax : 880-2-8615583,
E-mail : laila@udhaka.net
** Department of Biochemistry and Metabolism, BIRDEM Hospital, Shahbag,
Dhaka-1000, Bangladesh.
Abstract
The functions of peripheral blood neutrophils were studied in patients
suffering from Type I diabetes. The locomotor response towards towards
N-formyl-methionyl-leucyl-phenylalanine (FMLP) was studied using a
polarization assay. A significantly high proportion of neutrophils
from the patients were found to be in the polarized form at the baseline
level (p<0.001), and their dose response to FMLP was lower than
for healthy control subjects. In quantitative nitroblue tetrazolium
(NBT) dye reduction tests also, neutrophils from diabetic patients
were found to be more activated at the baseline level (p<0.05),
and, on activation, their ability to reduce the dye was less stimulated
than for those from healthy controls. These observations suggest that
neutrophils are already activated at the resting state in diabetics.
The proportion of neutrophils from the patients phagocytic to Saccharomyces
cerevisiae was observed to be similar to that of the controls, but
the number of activated yeast cells attached was lower. Impairment
in phagocytic function in diabetics was observed in that killing of
E. coli by neutrophils from the patients was significantly reduced
(p<0.05) as compared to those from healthy control subjects. Neutrophil
bactericidal activity in patients with moderate or acute diabetes
was also significantly suppressed than those with mild diabetes. These
findings indicate that there is considerable impairment of neutrophil
function in diabetic patients, and that this may contribute to the
severe and protracted infection often seen in these patients.
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THIAMINE CONTENT IN BRRI RICE VARIETIES
Fatema BEGUM *, K. A. Kabir, Majeda Begum
Grain Quality and Nutrition Division, Bangladesh Rice Research Institute,
Gazipur 1701, Bangladesh
Institute of Food Science and Technology, BCSIR, Dhaka 1205, Bangladesh
(Received for publication, 29 August 2000; and in revised form, 30
November 2000)
Author to whom all correspondence should be addressed.
Abstract
Rice is a good source of thiamine (vitamin B1). Its content in fourteen
modern rice varieties developed at BRRI was determined by a modified
thiocrome method. The loss of this vitamin during milling and cooking
was also estimated. Thiamine content in fourteen non-parboiled brown
rice varied from 0.288 mg/100g to 0.413 mg/100 g, and in parboiled
brown rice from 0.248 mg/100g to 0.367 mg/100 g. Thus, during parboiling
11.0% to 19.0% thiamine was lost. Loss of thiamine during milling
varied from 67% to 75% for non-parboiled and 11% to 26% for parboiled
rice. The loss during milling increased with the increase of degree
of milling. The degree of milling (bran removal from brown rice) was
more for non-parboiled rice than for parboiled rice at equal time
of polishing. At similar degree of milling, non-parboiled rice lost
more thiamine. The lost thiamine went with the bran. Thiamine was
also lost during cooking, Non-parboiled and parboiled milled rice
lost 85% to 97% and 73% to 92% respectively when cooked in excess
water and the excess water (gruel) drained out. The loss of thiamine
declined to 30% -49% and 30%-38% respectively for non-parboiled and
parboiled rice when cooked in optimum water with all the water allowed
to soak into the cooked rice and no gruel being drained out.
Key Words: Thiamine, BRRI rice
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COMPARATIVE STUDY OF MOSQUITO LARVICIDAL ACTIVITY OF LOCALLY ISOLATED
BACILLUS SPHAERICUS STRAINS AND COMMERCIALLY AVAILABLE ONES
A. K. M Mahbub Hasan, M. Jahangir, K. A. Rahim, M. Rahman*
Department of Biochemistry, University of Dhaka, Dhaka-1000, Bangladesh
(Received for publication, 30 October 2000; and in revised form 05
May 2001)
*Author to whom all correspondence should be addressed,
E-Mail: mrahman@udhaka.net
Abstract
Mosquito larvicidal activity of locally isolated bacteria, Bacillus
sphaericus strain SI-1 (Bs S!-1), has been determined and compared
with those of commercially available bacterial strains, Bacillus thuringiensis
israelensis (Bti), Bacillus sphaericus strain 1593 (Bs 1593) and Bacillus
sphaericus strain 2362 (Bs 2362). The spores from Bs SI-1 were more
potent as mosquito larvicidal gent than those from Bs 1593 and Bs
2362 while those from Bti were the most potent. When the mosquito
larvicidal activities of crude protein extracts of these organism
were compared, it was found to decrease in the following order: Bti>Bs
1593>BsSI-1>Bs 2362
Key Words: 3rd instar mosquito larvae/ B. Thuringiensis israelensis/
B. shaericus
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