Presence Of Gossypol Research Articles

Progressive methods of alkaline refining and bleaching of cottonseed oil

The article presents data from a study of the refining process of cottonseed oil, which differs from other vegetable oils in its complex composition and the presence of gossypol, which requires the use of alkali solutions (NaOH) of high concentration and in excess quantities. The use of magnetized solutions of sodium aluminate with a concentration of 15 to 25% has been proposed as an alkaline agent. Studies have shown that with the action of this reagent, a decrease in the acid number and color index of both press oil and oils obtained by extraction is observed.

Features of bleaching cottonseed oil with local adsorbents

The article presents research data on the process of adsorption refining (bleaching) of cottonseed oil, which differs from other vegetable oils in its complex composition and the presence of gossypol. Activated Tulsoh palygorskite has been proposed as a bleaching adsorbent. Studies have shown that the introduction of palygorskite in an amount of 1.0 to 2.5% helps reduce the color of both press oil and oils obtained by extraction.

Ultrasonic-aided extraction and degossypolization of cottonseed meal protein: Optimization and characterization of functional traits and molecular structure

Cottonseed meal (CM) is a useful protein resource, but the presence of gossypol (a toxic compound) limits it utilization in industry. To reduce the gossypol content, the use of ultrasonication in extracting protein from CM was explored. Following single-factor experiments, operative limits of independent variables affecting removal ratio of total-gossypol (RRTG) and extractability of CM protein (CMP) were achieved as temperature (35–55 °C), sonication power (250–350 W), time (12–24 min), and NaOH concentration (2–6 g/L). Box-Behnken’s Design centered on a 3–level-4–factor was employed to optimize ultrasonication conditions on the yield and RRTG of CMP. The predictive models were statistically adequate (p < 0.0001) to reflect the experimental results of the responses as verified by insignificant lack-of-fit (p ≥ 0.1333) and high coefficient of determination (R2 ≥ 0.976) values. The optimized sonication conditions for two responses were 53 °C, 320 W, 21 min, and 4.6 g-NaOH/L. Under optimized conditions, the observed removal ratio of free- and total-gossypol and yield values were 93.21 %, 87.56 %, and 58.23 %, which substantially increased by 15.64 %, 12.88 %, and 29.56 %, respectively over control (alkaline extraction). Furthermore, sonicated isolate showed an increase in solubility and emulsion property relative to control, buttressed by particle sizing and zeta potential outcomes. Sodium dodecyl sulfide polyacrylamide gel electrophoresis (SDS-PAGE), Fourier Transform Infrared (FTIR) spectroscopy, atomic force microscopy (AFM), and amino acid data showed notable changes in molecular weight, functional groups, surface topography, and hydrophobic amino acid content of CMP, respectively (i.e., after sonication), suggesting partial unfolding in CMP conformation. Accordingly, CMP isolates (especially the sonicated protein) could be considered edible because of the observed low gossypol content (< 0.045 %) and thus can be utilized as natural additives in food formulations.

Low Gossypol Containing Cottonseed: Not only a Fibre but also a Food Crop

We achieved self-sufficiency in food grains but are still deficient in pulses and oilseeds production. Cottonseed is a good source of quality oil and is rich in protein. But the presence of gossypol in the seed makes it toxic for human consumption. Therefore, low gossypol cultivars were developed either through genetic modification or screening and conventional breeding techniques. Texas A&M University patented the genetically modified ultra-low gossypol (< 450 mg kg−1) cultivar—TAM66274. Our breeders developed cultivars with gossypol content as low as 1100 mg kg−1 using conventional breeding techniques. Cottonseed meal, after oil extraction, can be used as a protein supplement similar to soybean. Cotton breeders need to screen the available germplasm and cultivars for low gossypol as well as high oil and fibre productivity. Thus, developing low and ultra-low gossypol cultivars will be a boon to our country.

Correlation of (+) Gossypol Level in Seeds of Cotton Hybrids to Insect and Disease Resistance

Cotton is the most important fibre crop and the seed from the plant is a rich source of high quality protein and oil. However, the use of cottonseed as a feed for animals is limited by the presence of gossypol, which is contained in glands in the seed. Gossypol occurs in two stereoenantiomers referred to as (+)-and (−)-gossypol. Most of the toxicity of gossypol resides in the (−)- enantiomer. Gossypol helps protect the plant from pests. However, there is very limited information on how the level (+)-and (−)-gossypol enantiomers correlate with insect and disease resistance. To understand the influence of (+)-gossypol level in seeds on insect and disease resistance we have initiated a study to examine if a correlations exists between percent (+)-gossypol in the seed and resistance to pests. The objective of our research was to develop cotton breeding material with good agronomic qualities that are suited for growing in Uzbekistan, and with a high percentage of (+)-gossypol and determine resistance to insects and pathogens. Results from our research showed that it should be possible to develop cotton breeding material that exhibit the high (+)-gossypol trait in seed and provide suitable insect and diseases resistance with good agronomic traits.

Effects of Maternal Dietary Cottonseed on the Profile of Minerals in the Testes of the Lamb.

The use of cotton co-products in animal feed is restricted by the presence of gossypol, which is a toxic and highly reactive molecule of complex minerals. In mammals, part of the offspring phenotype is influenced by dam nutrition. The aim of this study was to investigate the effect of ewe diet, with and without cottonseed (gossypol), on the testicular development of lambs from birth to weaning through the assessment of lamb live weight (LW), macro and histological morphology of testes, and mass fraction of chemical elements by neutron activation analysis (NAA) and microprobe X-ray fluorescence spectroscopy, as well as the multielement distribution map in the testes. Eighteen lambs were used with an average LW at birth of 4 ± 1.0kg. All lambs were offspring of Santa Inês ewes, fed on ration either with or without cottonseed during mating, gestation, and lactation, thus forming two treatments: control group (C) without cottonseed and treatment group with cottonseed (G). The animals were weighed from birth to 60days of age, at fortnightly intervals. At 60days of age, the lambs were orchidectomized to collect their testes for macroscopy, histological, neutron activation, and X-ray fluorescence analysis. Besides dry matter (DM), protein, ether extract (EE), calcium (Ca), and potassium (K) were higher in the ewe milk from the C group compared with the G group (P < 0.05). Lambs from the C group showed higher LW from 45days onwards, as well as higher average daily gain when compared with the G group (P < 0.05). They also presented higher testicular weight, volume, length, width, as well as tubule and lumen diameters compared with lambs from the G treatment (P < 0.05). Multielementary NAA revealed higher mass fractions of rubidium (Rb), selenium (Se), and cesium (Cs) in the testes of lambs from the C group when compared with the G group, while G showed higher zinc (Zn) content (P < 0.05). No differences between treatments were found for element levels and distribution using X-ray fluorescence microanalysis (P > 0.05). In conclusion, the maternal cottonseed diet compromised performance and testes development of the lambs and reduce the content of Se in the testes.

Morphological-metric, ultrastructural and immunohistochemical effects of gossypol on cultured granulosa cells and oocytes of ewes using MOEPF

Manipulation of oocytes enclosed in preantral follicles (MOEPF) allows for analyzing follicular development and use of this biotechnology in the pre-analysis of the beneficial or toxic effects of bio-products on granulosa cells and oocytes at different developmental stages. In this study, there was evaluation of the effects of gossypol by culturing granulosa cells and oocytes in ewe ovarian tissues. Ovarian tissues were cultured with gossypol at 37 °C, in humidified air and 5% CO2. Variables that were evaluated were morphology, morphometry, ultrastructure and abundance of estradiol receptor α (α-ER). There were no differences in developmental characteristics when there was treatment with any of the gossypol doses that were evaluated. Immunostaining indicated that when the gossypol dose increases, the abundance of α-ER also increases in the cytoplasm, nucleus, and granulosa cells. Findings with the ultrastructural analysis indicated that for granulosa cells there was fewer cells and greater disorganization and a lack of structural integrity of follicular cell layers as a result of all gossypol treatments. The culture of oocytes in preantral ovarian follicles in presence of gossypol did not affect the morphological-metric structure at the doses evaluated. The findings with evaluation of ultrastructural and immunohistochemical structures indicated granulosa cells and α-ER were affected by the treatments with gossypol indicating there were effects of this compound on ovarian function in sheep. This study indicated there is a toxic action of gossypol when using the biotechnology, MOEPF. Thus, gossypol negatively affects granulosa cell development and structural integrity of preantral follicles in sheep.

GOSSYPOL PROMOTES THE DEGENERATION OF CHICKEN OVARIAN FOLLICLES IN VITRO

Gossypol, a phenolic compound produced by the pigment glands of cotton, is known to affect male reproduction. In females, exposure to gossypol has been associated with interference with the estrous cycle and embryo development. In laying hens fed cottonseed, gossypol was found to reduce egg production and weight and to cause discoloration of the egg yolk and/or albumen. It is probable that gossypol directly affects ovarian follicles, but this has not been confirmed experimentally yet. Thus, the aim of the present study was to determine if gossypol affected cultivated ovarian follicles of the chicken. Ovarian follicles of adult female chickens were cultivated with different concentrations of gossypol (0, 5, 10 and 20 μg/mL) and classified according to the stage of development as primordial, transitional, primary, secondary or antral, and as viable or atretic. The percentages of viable and atretic follicles in the ovaries cultivated for 24 hours in the presence of gossypol were significantly different from those of the controls for all types of follicles except for secondary follicles, but in all types after cultivation for 7 days. The percentage of viable follicles was higher than that of atretic follicles in ovaries cultivated without gossypol. In contrast, ovaries cultivated with gossypol showed a predominance of atretic follicles. Gossypol increased the proportion of atretic follicles at all stages of development in cultivated chicken ovaries. Thus, gossypol may affect ovarian follicular viability and maturation, which might interfere with female fertility.

Block of Recombinant T-Type Calcium Channels by Gossypol, a Potential Contraceptive

Gossypol is a bioactive compound associated with some male contraceptive properties. Experimental evidences have shown that gossypol inhibits spermatogenesis as well as spermatozoa motility and viability. T-type calcium channels, or CaV3 channels, have been found in both spermatogenic and sperm mammalian cells; they play an essential role in spermatogenesis, motility, capacitation and acrosome reaction. Recent studies show that native T-type calcium currents from murine spermatogenic cells are inhibited by micromolar concentrations of gossypol in a non-reversible process. However, until now there was no data showing whether gossypol preferentially blocks any member of the CaV3 channels subfamily, neither information about the blocking mechanism. Here, we performed whole-cell patch-clamp recordings of HEK-293 cells stably expressing human CaV3 channels (CaV3.1, CaV3.2 and CaV3.3) to address these questions. We found that gossypol blocks the three CaV3 channels in a concentration-response manner with similar IC50s ranging from 6 to 11 μM. Block by gossypol is not completely irreversible although T-type currents were poorly recovered (10-30%). Voltage-dependence of activation was not modified by gossypol, but steady-state inactivation was shifted to more negative potentials (around 10 mV), and block at −30 mV was stronger when using more depolarized holding potentials. In addition, the inactivated-state of CaV3 channels was stabilized in the presence of gossypol as the recovery from inactivation was delayed and incomplete. A modest use-dependent component was observed only in CaV3.1. Current kinetics were not affected by gossypol. The results demonstrate that gossypol blocks human CaV3 channels at micromolar concentrations with preferential binding to inactivated-states, and suggest that sperm cells will be more sensitive to gossypol during the hyperpolarization that take place along the capacitation process. These results provide new insights about the potential use of gossypol as a contraceptive.Supported by CONACYT-MEXICO 167790.

Elimination of Gossypol in Cottonseed will Improve its Utilization

Gossypol, a naturally occurring terpenoid found in pigment glands located throughout the cotton plant, is an effective insect deterrent, but is also a cumulative toxin in simple-stomached animals. Plant biotechnology utilizing RNAi was used to create a plant that has no gossypol in the seed while retaining gossypol in all other plant tissues to prevent predation. Since cotton is drought and heat tolerant, it is well suited to serve as a source of both food and fiber as climate change puts other crops in jeopardy.Agrobacterium transformation was used to insert into the cotton nuclear genome a construct containing a seed specific promoter driving an RNAi hairpin that suppresses delta-cadinene synthase. This enzyme plays a critical role early in building gossypol. This biotechnology-based proof of concept provides strong evidence that it is possible to produce a plant that retains its natural defense mechanism in the non-seed tissues while producing a drought and heat tolerant source of protein in the gossypol-free cottonseed.The presence of Gossypol in cotton seed means all the protein produced by the cotton plant is relegated to ruminant feed and (in miniscule amounts) aquacultre. Recent research demonstrates 100% replacement of fishmeal with Ultra-Low Gossypol Cottonseed (ULGCS) in the feeds of several aquaculture species without a decrease in performance.Each year about 10-11 million metric tons of cottonseed protein are produced worldwide. Without gossypol, this is enough protein to satisfy the daily, basic protein needs (50 grams/person) of more than 600 million people for one year. Food scientists have also created a wide range of food products from ULGCS, including hummus, plant-based dairy substitutes, a peanut butter alternative and protein fortified beverages. Elimination of gossypol in cottonseed could greatly improve utilization of this valuable protein resource for global food and fiber security as we move into an era of uncertain climate conditions.

P-0076 18F-FDG and Gossypol: Studies in Hepatocellular Carcinoma

IntroductionMalignant cells require high energy via glycolytic generation of ATP for cell proliferation and survival, a process that is thought to be mediated by glucose transporters (GLUTs). Notably, GLUT1 is overexpressed and confers poor prognosis in a wide range of solid tumors, including liver tumors. A recent study has shown that expression of GLUT1 is increased in Hepatocellular Carcinoma (HCC) and promotes tumorigenesis. Conversely, suppression of GLUT1 expression by small interfering RNA significantly impaired tumorigenicity of HCC cells in in vitro models, suggesting that GLUT1 as an innovative therapeutic target for this highly aggressive tumor. Positron Emission Tomography (PET) using the radiolabeled glucose analogue 18F-FDG enables the detection of increased glycolysis events in cancer cells. Glucose is transported into the cell mainly through the GLUT-1 and -3. Gossypol is a natural compound that has demonstrated anticancer effect in several tumor types. It is known that gossypol is a competitive inhibitor of the GLUT1. The aim of this study is to test the anticancer effect of gossypol in HCC cell lines, as well as check its effect on 18F-FDG uptake. MethodsThe cell lines used are HepG2 (wp53), HuH7 (mp53) and Hep3b2.1-7 (p53 null). These cell lines were propagated in the presence of gossypol in several concentrations. Cell proliferation was evaluated by the MTT test, in order to obtain dose-response curves. After that the type of cell death (necrosis or apoptosis) and the percentage of live cells were assessed by flow cytometry for the concentration of drug able to induce half maximal inhibitory concentration (IC50).For uptake studies, 18F-FDG was incubated in a cell suspension with 2×106 cells/ml (25µCi/ml) in cells pre-incubated with gossypol and control cells. Samples were collected to Eppendorf tubes for tracer uptake calculation. Eppendorfs were then centrifuged and radioactivity of cell pellets and supernatants was measured with a well-type gamma counter. ResultsThis study demonstrates that the concentrations of gossypol necessary to achieve the IC50 is higher for HuH7 cell line (IC50(24h)=7.5µM). Interestingly, the cell line more sensitive to this compound is Hep3B2.1-7 (IC50(24h)=2.6µM), which may be related to the fact that these cells do not express p53. The cellular response is dependent on time, for each of the cell lines studied. Flow cytometry results show that gossypol induces high apoptosis in HepG2 and HuH7 cell lines with lower induction of necrosis. In Hep3B2.1-7 cell line there is a balance between apoptosis and necrosis. In addition, for the three cell lines studied, gossypol was able to decrease the percentage of 18F-FDG uptake in the similar way. ConclusionThese results shown that gossypol has anti-proliferative effect on HCC. Gossypol also has shown ability to decrease the uptake of 18F-FDG in the three cell lines. More studies must be done to clarify the role of p53 in the anti-proliferative effect of this compound in HCC as well as the effect in the uptake of the 18F-FDG. These preliminary results are quite useful in clinical practice.

Gossypol decreases tumor necrosis factor-α-induced intercellular adhesion molecule-1 expression via suppression of NF-κB activity

Gossypol is a yellowish polyphenolic compound originally from cotton plant, which has been shown to exert a potential for anti-cancer and anti-inflammatory effects. However, its molecular mechanism is not thoroughly understood on breast cancer cells known to highly express intercellular adhesion molecule-1 (ICAM-1) for their adhesion and metastasis. This study aims to investigate the effect of gossypol on tumor necrosis factor (TNF)-α-stimulated ICAM-1 via nuclear factor-kappa B (NF-κB) activity. Gossypol was shown to inhibit TNF-α-induced ICAM-1 expression and U937 cell adhesion to MDA-MB-231 and MCF-7 cells. Additionally, TNF-α-induced MDA-MB-231 cell invasion was blocked in the presence of gossypol. Chromatin immunoprecipitation analysis demonstrated that gossypol blocks NF-κB binding on the ICAM-1 promoter regions. Additionally, TNF-α-induced NF-κB activation was completely suppressed in the presence of gossypol. Gossypol did not directly suppress the binding of NF-κB to the DNA but rather inhibited the nuclear translocation of p65 and p50 via phosphorylation and degradation of IκB. We also found that gossypol suppresses NF-κB activation induced by a wide variety of agents, including taxol, okadaic acid, and phorbol myristate acetate. Taken together, gossypol effectively inhibited TNF-α-induced ICAM-1 expression via the suppression of NF-κB activation and in vitro adhesion and invasion in human breast cancer cells.

Gossypol suppresses NF-κB activity and NF-κB-related gene expression in human leukemia U937 cells

Recent studies indicate that gossypol possesses potent antitumor activities in vitro and in vivo. The nuclear factor-kappa B (NF-κB) plays an important role in tumor cell growth, proliferation, invasion, and survival. In this study, we investigated the effects and the molecular mechanisms of gossypol on NF-κB activation and NF-κB-related gene expression in human leukemia U937 cells. Treatment with concentrations of gossypol greater than 10 μM resulted in significant cell cytotoxicity and DNA fragmentation, indicative of apoptosis. Treatment with 10 μM gossypol also induced caspase-3 activation and poly(ADP-ribose)polymerase (PARP) cleavage, and resulted in the induction of apoptosis in approximately 20% of cells as determined by annexin-V staining 24 h after treatment. Furthermore, gossypol exposure decreased the DNA-binding activity of NF-κB in a concentration-dependent manner. Treatment with gossypol also downregulated expression of NF-κB-regulated gene products, including inhibitor of apoptosis protein (IAP)-1, IAP-2, and X-linked IAP. Attenuation of NF-κB activity by pretreatment with PDTC, an NF-κB nuclear translocation inhibitor, significantly induced apoptosis in the presence of gossypol. Gossypol also suppressed NF-κB p65 mRNA accumulation, resulting in suppression of total NF-κB activity. This was associated with a downregulation of Sp1-binding activity, a transcription factor controlling p65 transcription. These results suggest that gossypol-induced apoptosis partially involves suppression of NF-κB activity.

Silencing a cotton bollworm P450 monooxygenase gene by plant-mediated RNAi impairs larval tolerance of gossypol

We identify a cytochrome P450 gene (CYP6AE14) from cotton bollworm (Helicoverpa armigera), which permits this herbivore to tolerate otherwise inhibitory concentrations of the cotton metabolite, gossypol. CYP6AE14 is highly expressed in the midgut and its expression correlates with larval growth when gossypol is included in the diet. When larvae are fed plant material expressing double-stranded RNA (dsRNA) specific to CYP6AE14, levels of this transcript in the midgut decrease and larval growth is retarded. Both effects are more dramatic in the presence of gossypol. As a glutathione-S-transferase gene (GST1) is silenced in GST1 dsRNA-expressing plants, feeding insects plant material expressing dsRNA may be a general strategy to trigger RNA interference and could find applications in entomological research and field control of insect pests.

Introgression of a gene for delayed pigment gland morphogenesis from Gossypium bickii into upland cotton

The presence of gossypol and its derivatives above the WHO/FAO standards (0.02–0.04%) in cotton seed oil and meal limits its usage as food and feed. To the contrary, the presence of pigment glands filled with gossypol and its derivatives helps to protect cotton plants from phytophageous pests. Thus a desirable cultivar would have glandless seeds on a glanded plant. This paper describes results on the successful introgression of this trait from Gossypium bickii into cultivated upland cotton. Five different tri-specific hybrids (ABH1, ABH2, ABH3, ABH4 and ABH5) were obtained by crossing the amphidiploid F1 (G. arboreum × G. bickii) with different gland genotypes of G. hirsutum as male parent. The hybrids were highly sterile, and their chromosome configuration at meiosis metaphase 1 (M1) in pollen mother cell (PMC) was 2n = 52 = 41.04 I + 4.54 II + 0.57 III + 0.04 IV. All five hybrids were similar in morphological characters, except for the gland expression and gossypol contents. The hybrid (ABH3) derived from genotype Gl2Gl2gl3gl3 of upland cotton (a single gene dominant line) had completely introgressed the target trait of G. bickii. While ABH1 and ABH2, which derived from recessive (gl2gl2gl3gl3) or dominant (GlGl) glandless upland cotton genotypes, had glandless seeds too, but the density and size of the glands on the plant were reduced significantly.

Cottonseed Meal Diets Improve Body Weight Uniformity in Broiler Breeder Pullets

Due to its low nutrient density, cottonseed meal (CSM) may be a potential alternative feed ingredient for soybean meal (SBM) in broiler breeder pullet diets to improve flock BW uniformity. A major concern when utilizing CSM in poultry diets, however, is the presence of gossypol. It was determined in an initial experiment that when broiler breeder hens are fed a diet containing CSM, gossypol accumulates in the liver. When CSM is removed from the diet, however, hepatic gossypol levels dissipate within a few weeks. In a subsequent study, in order to achieve the breeder guideline ideal weight, broiler breeder pullets reared with a diet containing CSM from 2 to 18 wk of age had to be fed a larger amount than birds consuming a standard SBM diet. The CV of bird weight was significantly lower during the rearing period for birds reared with the corn and CSM diet. This difference in uniformity was maintained as the hens entered the breeding period. Egg weight, hatchability, and fertility were equivalent for hens reared with a diet containing CSM and those reared with a standard diet throughout the growing period. The results suggest that broiler breeder pullets reared on a diet containing CSM as the major protein source have improved flock BW uniformity and normal subsequent reproductive performance.

The Use of Cottonseed Meal with or without Added Soapstock in Laying Hen Diets

Laying hens fed diets containing cottonseed meal (CSM) can produce eggs that have pink albumen discolorations and brown yolks due to the respective presence of cyclopropenoid fatty acids and free gossypol in the CSM. The potential concentration of these two compounds is less in the CSM produced in the modern expander-solvent cottonseed mills, which leave little residual oil in the meal, than in older expeller plants. However, part or all of the possible benefit can be lost if soapstock is added back to the CSM. An experiment was conducted to examine the degree of egg discoloration produced when feeding CSM obtained from an expander-solvent extraction mill. The CSM used in this study contained 4.2% ether extract, indicating a moderate amount of soapstock had been added back to the meal. Egg-yolk discoloration associated with the presence of gossypol was observed when feeding diets containing above 10% CSM (100 ppm free gossypol). In subsequent experiments it was determined that egg-yolk discoloration could be greatly reduced when using a cottonseed meal without soapstock and that some hens were insensitive to the egg discoloration effects of gossypol.

A detoxification method of Khorasan cottonseed meal gossypol for broiler chicken rations

Cotton is one of the main agricultural crops of Iran. The potential of cottonseed meal (CSM) for poultry nutrition is limited by the presence of gossypol, a toxic polyphenolic pigment. Gossypol exists in CSM in two forms, free and bound. Free gossypol, as defined by AOCS official methods, are those gossypol and gossypol derivatives that are soluble in aqueous acetone and are physiologically active. Bound gossypol is insoluble in ether, chloroform or aqueous acetone and for the most part is physiologically inactive (Berardi &amp; Goldblatt, 1980). The objectives of the experiments reported herein were to study of gossypol reduction by dehydrated ferro sulfate( DFS) and lecithin and also the feeding value of a commercially processed CSM in broiler diets.

Growth, feed utilization and body composition of tilapia (Oreochromis sp.) fed with cottonseed meal-based diets in a recirculating system

The suitability of cottonseed meal (CSM) as a major source of plant protein in feeds for tilapia (Oreochromis sp.) was tested by examining growth and feed intake, feed digestibility, liver gossypol concentrations, feed utilization, and body mineral composition. Juvenile tilapia at an initial average size of 11.8 +/- 1.6 g were divided into triplicate groups per dietary treatment and offered five different formulated diets. In these feeds fish meal (FM) protein was gradually replaced by protein from CSM (0, 25, 50, 75, and 100%; diets 1, 2, 3, 4 and 5, respectively). The experiments were conducted in a recirculation system at a water temperature of 27 +/- 1 degrees C in glass aquaria for 16 weeks. Tilapia growth did not differ significantly (P > 0.05) with up to 50% substitution of FM with CSM. Fish meal replacement above 50% resulted in significant growth decline with time. Fish fed with 100% FM and diets including 50% CSM had significantly better daily weight gain, daily feed intake and feed efficiency ratio than those fed with 100% CSM. Fish fed with 75% CSM and above had lower concentrations of body iron, calcium and phosphorus than controls (100% FM). Concentrations of total gossypol in diets (ranging from 0.11 to 0.44% in diets 2-5) resulted in proportional increase of total gossypol in fish liver (32.3, 72.3, 99.4 and 132.1 microgram g(-1) wet weight) in groups fed with diet 2, 3, 4, and 5, respectively. We concluded that CSM can partially replace FM as a main source of protein in feed for tilapia at not more than 50%. The presence of gossypol in CSM was identified as the major limiting factor for acceptance and utilization of CSM-based diets in tilapia farming.

Host plant effects on activity of the mitosporic fungi Beauveria bassiana and Paecilomyces fumosoroseus against two populations of Bemisia whiteflies (Homoptera: Aleyrodidae).

Laboratory bioassays were conducted to determine the effect of host plant on mycosis in two geographically distinct populations of early 2nd-instar nymphs of Bemisia argentifolii Bellows & Perring from the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Paecilomyces fumosoroseus (Wize) Brown & Smith. Mycosis in B. argentifolii nymphs varied according to the host plant on which the nymphs were reared but not according to the population. Both populations of whiteflies reared on cotton were consistently significantly less susceptible to infection by either fungus than when reared on melon. We hypothesized that the cotton plant produced a fungal inhibitor that may confer protection on whiteflies feeding (and possibly sequestering) upon it. Germination of conidia of both fungi was strongly inhibited (below 12% germination) on the cuticle of nymphs reared on cotton but was over 95% on the cuticle of nymphs reared on melon. We further hypothesized that the terpenoid gossypol, produced by many cultivars of cotton, might have been involved in antibiosis. Gossypol mixed with Noble agar at five concentrations was tested for its effects on germination of conidia of both fungi. P. fumosoroseus was highly tolerant of gossypol, even at the relatively high concentration of 1000 ppm, while B. bassiana tolerated gossypol at concentrations up to 500 ppm and strong inhibition only occurred in presence of gossypol at 1000 ppm. Our in vivo findings on cotton and on the insect's cuticle pointed at a potential host plant-mediated antibiosis. The in vitro tolerance of P. fumosoroseus and partial tolerance of B. bassiana to gossypol disagreed with our in vivo data. Gossypol concentrations higher than 1000 ppm might have increased the sensitivity of the fungi in our in vitro tests. Sequestered gossypol (and/or other cotton plant allelochemicals) by B. argentifolii nymphs would explain, at least partially, the insect's defense against the pathogens.