Dynamics of limited neoplastic growth on Pongamia pinnata (L.) (Fabaceae) leaf, induced by Aceria pongamiae (Acari: Eriophyidae).

BACKGROUND: Galls or the neoplastic growth on plants result from a complex type of interaction between the inducers (Acari, Insects, Microbes and Nematodes) and plants. The present study sheds light on the gall inducing habit of a highly host specific eriophyid mite, Aceria pongamiae, on the leaves of Pongamia pinnata leading to the production of abnormal pouch like outgrowths on the adaxial and abaxial surfaces of the foliage. Each leaf gall is a highly complex, irregular massive structure, and the formation of which often leads to complete destruction of leaves, especially during heavy mite infestation, and thereby adversely affecting the physiology and growth of the host plant. RESULTS: The study was carried out by making comparative observations on FE-SEM histological sections of galls representing four different growth stages categorized on the basis of difference in age groups. Apart from variations in cell metaplasia, a dramatic change was observed in the abaxial-adaxial polarity of the laminar surfaces also throughout the developmental sequence of galls, in all the four growth stages. Significant variations could be observed in the anti-oxidative potency as well as elemental composition in the all the four age groups of galls, and also revealed ATR-FTIR pattern of gall formation. CONCLUSION: Being the first attempt to unravel the mystery of gall induction by eriophyids in general and by A. pongamiae in particular, on its host plant P.pinnata, by shedding light on the structural and histological alterations taking place during leaf gall formation under the influence of the mite, the current study is to be treated as the model of plant-animal interactive system.

Enzymatic characterization of the saliva of the eriophyid mite, Aceria pongamiae Keifer1966 (Acari: Eriophyidae) and the bacterial endobiome of the galls induced on Pongamia pinnata (L.) Pierre (Fabaceae).

Galls, like other regular plant organs, possess their own histological and physiological features. A high degree of specificity is maintained between the host and the inducer, and hence gall morphogenesis is highly conserved and would help trace gall lineages and cell fate. The present study highlights the induction and subsequent development of leaf galls on the Indian Beech tree, Pongamia pinnata (L) Pierre (Fabaceae), mediated through the active participation of a gall-inducing species of eriophyid mite, Aceria pongamiae Keifer and gall-associated bacterial endobiome. The saliva of A. pongamiae and selected strains of gall-associated bacterial endobiome were characterized in part during the study. Three strains of Staphylococcus arlettae (PGP1-3) and one strain of Bacillus flexus (PGP4) were identified from the leaf galls through 16S rDNA sequencing. The mite saliva displayed tryptophanase activity, and the bacterial strains showed differential enzyme activities (protease, amylase, cellulase, DNAse, pectinase, tryptophanase, and catalase). All four strains of bacterial endobiome exhibited unique metal tolerance as well as pH and temperature regulating activity. Evaluation of the potential role of the mite saliva and the gall associated bacterial endobiome in gallogenesis was done by monitoring the plant growth-promoting activity of the salivary extract and the isolated bacterial strains through in vitro seed (Vigna radiata) germination assay. Salivary extract of the mite showed the highest rate of plant growth-promoting activity compared with that of the isolated strains of bacterial endobiome. The present study forms the first attempt that illustrates the characteristic features of the saliva of the gall inducer and the gall associated bacterial endobiome. Based on the results of the current study, we suggest that eriophyid mite saliva and the gall-associated microbes play significant roles in the induction of cecidia.

Two remarkable new species of oribatid mites (Acari: Oribatida) from Acacia litter of Kerala, India.

Two new oribatid mite species viz. Papillacarus (Vepracarus) acaciensis sp. nov. and Licneremaeus indicus sp. nov. belonging to the respective oribatid families, Lohmanniidae and Licneremaeidae are described and illustrated. Specimens of both species were collected from litter of Acacia auriculiformis Benth. (Leguminosae) growing in different localities of the Calicut University Campus, Malappuram Dt. of Kerala. The family Licneremaeidae is recorded for the first time from India. Identification keys to all known species of the nominative subgenus Vepracarus and the genus Licneremaeus are also provided.

Immune protection is dependent on the gut microbiome in a lethal mouse gammaherpesviral infection.

Immunopathogenesis in systemic viral infections can induce a septic state with leaky capillary syndrome, disseminated coagulopathy, and high mortality with limited treatment options. Murine gammaherpesvirus-68 (MHV-68) intraperitoneal infection is a gammaherpesvirus model for producing severe vasculitis, colitis and lethal hemorrhagic pneumonia in interferon gamma receptor-deficient (IFNγR-/-) mice. In prior work, treatment with myxomavirus-derived Serp-1 or a derivative peptide S-7 (G305TTASSDTAITLIPR319) induced immune protection, reduced disease severity and improved survival after MHV-68 infection. Here, we investigate the gut bacterial microbiome in MHV-68 infection. Antibiotic suppression markedly accelerated MHV-68 pathology causing pulmonary consolidation and hemorrhage, increased mortality and specific modification of gut microbiota. Serp-1 and S-7 reduced pulmonary pathology and detectable MHV-68 with increased CD3 and CD8 cells. Treatment efficacy was lost after antibiotic treatments with associated specific changes in the gut bacterial microbiota. In summary, transkingdom host-virus-microbiome interactions in gammaherpesvirus infection influences gammaherpesviral infection severity and reduces immune modulating therapeutic efficacy.

Relationship of one form of human histamine-releasing factor to connective tissue activating peptide-III.

We have previously reported purification of three forms of histamine-releasing factors (HRFs) from mixtures of streptokinase-streptodornase stimulated human mononuclear cells and platelets with apparent molecular masses of 10-12, 15-17, and 40-41 kD (1989. J. Clin. Invest. 83:1204-1210). We have also prepared mouse MAbs against the 10-12-kD HRF (1989. J. Allergy Clin. Immunol. 83:281). Affinity-purified 10-12-kD HRF appears as a broad band upon polyacrylamide gel electrophoresis in the presence of SDS. We determined the NH2-terminal amino acid sequence of the top and bottom halves of this broad band. Sequence analysis revealed striking homology between this HRF and connective tissue activating peptide-III (CTAP-III), a platelet-derived 8-10-kD protein known to cause mitogenesis and extracellular matrix formation in fibroblast cultures. 19 of 21 NH2-terminal residues in the top half of the HRF band were identical to the NH2-terminal sequence of CTAP-III. 20 of 21 NH2-terminal residues in the bottom half were identical to the NH2-terminal sequence of neutrophil-activating peptide-2, which is derived from CTAP-III by proteolytic cleavage between residues 15 and 16. Purified CTAP-III also released histamine from basophils. Rabbit antiserum raised against either native or recombinant CTAP-III recognized affinity-purified HRF in immunodot blot assays, and MAb against HRF recognized CTAP-III in both dot blot and microtiter plate based immunoassays. These data demonstrate the first structural, functional, and immunologic relationship between one form of human HRF and a previously described cell product.

The effects of sulfhydryl-modifying reagents on cholecystokinin-receptor interactions in guinea pig gastric glands.

The effects of a number of different sulfhydryl agents on cholecystokinin (CCK)-binding sites in isolated fundic gastric glands and gastric mucosal membranes from guinea pigs were evaluated. [125I]CCK octapeptide binding was significantly reduced when gastric glands were pretreated with iodoacetamide (IA; 10 mM), p-chloromercuribenzoate (PCMB; 0.1 mM), or N-ethylmaleimide (NEM; 0.1 mM) at 24 C, but not by dithiothreitol (DTT; 1.0 mM) or dinitrothiobenzoic acid (DTNB; 10 mM). In contrast, inclusion of DTT or IA during binding led to significant increases in the amount of radioligand bound, while in the presence of DTNB binding was significantly reduced. Glycine-HCl wash of gastric glands pretreated with these agents indicated that NEM and IA reduced radioligand internalization by about 80% (P less than 0.001) and increased surface binding by 20% (P less than 0.01) and 76% (P less than 0.001), respectively. PCMB inhibited radioligand binding to surface sites by more than 90% and completely inhibited radioligand internalization. Gastric mucosal membranes bound significantly less radioligand after PCMB (80%) and NEM (26%) treatment compared to controls, and significantly more after IA treatment (162%). Scatchard analysis of the CCK-receptor interaction indicated two binding sites with dissociation constants of 0.71 and 11.7 nM, and binding capacities of 3.6 and 15.8 nmol/mg DNA, respectively. NEM and IA significantly increased the Kd of the high affinity site without affecting the binding parameters of the low affinity site; the low affinity site was eliminated by PCMB treatment, and the affinity and capacity of the high affinity site were significantly reduced. In the presence of DTT, [125I]CCK octapeptide binding to gastric glands was enhanced with a significant increase in the amount of radioligand in the internalized pool (39%; P less than 0.001) and no increase in binding to gastric mucosal membranes. These results suggest that sulfhydryl groups play an important role in CCK-receptor interactions.

Molecular identification and characterization of the gastrin receptor in guinea pig gastric glands.

The binding characteristics of 125I-labeled Leu15-gastrin and the molecular identification of the gastrin receptor was investigated in dispersed guinea pig gastric glands. The binding of [125I]gastrin to gastric glands was temperature dependent, saturable, and specific. At 37 C, the binding was rapid, became maximal within 10 min, and declined after 30 min; at 24 C, binding reached a steady state between 30 and 60 min. The dissociation of specifically bound gastrin was also rapid, with 35% of the radioligand dissociating in 5 min at 37 C. Gastrin displaced [125I]gastrin in a dose-dependent manner, with 50% displacement at 4.4 nM. Scatchard analysis of the saturation curve was best described by a one-site binding model with a Kd of 2.3 nM and maximum binding of 6.0 x 10(-10) M/mg DNA. A significant reduction of [125I]gastrin binding to glands occurred in the presence of GTP (0.1 mM), (Bu)2-cGMP (1.0 mM), and protease inhibitors. Chemical cross-linking studies using the cross-linking reagent disuccinimidyl suberate and sodium dodecyl sulfate-gel electrophoresis identified a major band with a mol wt of 78K and several other lower mol wt bands in the range of 60K, 48K, and 38K. Identical electrophoretic patterns were obtained when glands were bound and solubilized in the presence and absence of dithiothreitol, showing the lack of disulfide bonds in the gastrin receptor subunit structure. Since dithiothreitol significantly enhanced radioligand binding when present during binding, its observed actions are most likely in the intracellular processing of the radioligand and not at the receptor level.

Direct stimulation of nucleoside triphosphatase activity in bovine luteal nuclear membranes by human chorionic gonadotropin.

Nuclear membranes of bovine corpora lutea contain nucleoside triphosphatase (NTPase), an enzyme involved in the nucleocytoplasmic transfer of mRNA. Upon addition to nuclear membranes, hCG stimulated this enzyme, but not Mg2+-ATPase or NADH cytochrome c reductase, in a dose-, time-, and temperature-dependent manner. Heat-denatured hCG, however, had no effect on NTPase activity. hCG antisera blocked hCG's ability to stimulate the NTPase activity. While human LH also stimulated luteal nuclear membrane NTPase activity, a variety of other hormones tested, including alpha- and beta-subunits of hCG and 1 and 10 mM cAMP, had no effect on the enzyme. hCG's effect on NTPase is tissue specific in that it had no effect on liver or kidney nuclear membrane NTPase activity. In conclusion, the present data demonstrate that hCG acts directly on the luteal cell nucleus, thus raising the possibility that internalized hCG might influence nuclear functions before it is eventually degraded in lysosomes of luteal cells.

Direct stimulation of nucleoside triphosphatase activity in human ovarian nuclear membranes by human chorionic gonadotropin.

We previously reported that nuclei isolated from ovaries of premenopausal women contain binding sites for hCG/human LH (hLH). This study was undertaken to determine the possible functional significance of these nuclear binding sites. Upon addition to isolated ovarian (mostly luteal cells) nuclear membranes, hCG and hLH stimulated nucleoside triphosphatase (NTPase), an enzyme involved in nucleocytoplasmic transfer of mRNA, but not Mg2+-ATPase or NADH cytochrome c reductase activities, in a concentration-dependent manner. Heat-denatured hCG, isolated alpha- and beta-subunits of hCG, human FSH, PRL, and porcine relaxin had no effect on the enzyme. Addition of hCG antiserum blocked hCG's ability to stimulate NTPase activity. cAMP, which is a second messenger in hCG- and hLH-stimulated steroidogenesis, had no effect on NTPase activity. These results, which demonstrate that hCG acts on human ovarian nuclei directly, raise the possibility that internalized hCG might influence nuclear function(s) before it is eventually degraded in the lysosomes of ovarian cells.

Morphological and biochemical characterization of small and large bovine luteal cells during pregnancy.

Small (15-18 microns) and large (18-45 microns) luteal cells were obtained from bovine corpora lutea of pregnancy by centrifugal elutriation of enzymatically dispersed luteal cells. Small luteal cells accounted for about 85% and large luteal cells for 8-12% of total luteal cell population. Small luteal cells were characterized by a low cytoplasmic/nuclear ratio with cytoplasm containing mitochondria, lysosomes, lipid droplets, dense granules and endoplasmic reticulum. Large luteal cells possessed a higher cytoplasmic/nuclear ratio with cytoplasm containing more abundant mitochondria, lipid droplets, dense granules and lysosomes compared to small luteal cells. Some of the mitochondria were very long. Both small and large luteal cells contained scarce amounts of Golgi elements. Dense granules were found close to the nucleus in both cell types. The nucleus of both cell types was acentric, irregular in shape and contained a well-defined nucleolus. The highly condensed chromatin in small luteal cells was found at the nuclear periphery and in the central region. Dispersed chromatin was found throughout the nucleus with condensed chromatin at the nuclear periphery of large luteal cells. Macrophages and fibroblasts were occasionally found in small luteal cell preparations, but their morphology was quite distinct from both small and large luteal cells. Scanning electron microscopy revealed that the majority of the small and large luteal cells were spherical or slightly elongated in shape. Small luteal cells displayed the presence of blebs, ruffles and short microvilli. Large luteal cell surface contained ruffles and randomly distributed clusters of blebs of different sizes, predominantly spherical in shape with a smooth surface. Finger-like projections were also occasionally seen. Small luteal cells contained significantly lower amounts of protein, but the ratios between protein and DNA were similar in both cell types. The basal, human chorionic gonadotropin (hCG)- or cyclic AMP-stimulated progesterone production, the apparent dissociation constants for [125I]hCG binding and the apparent total number of available sites per cell were similar in small and large luteal cells. The activities of enzymes that are involved directly or indirectly in progesterone biosynthesis and those involved in general cellular metabolism and biosynthesis were also similar in small and large luteal cells with one exception. That is, the activities of 5'-nucleotidase and NADH cytochrome c reductase were significantly higher in small compared to large luteal cells.

How physicians feel about assisting female victims of intimate-partner violence.

PURPOSE: To assess the feelings of physicians about assisting female victims of intimate-partner violence (IPV), and to examine factors related to positive and negative feelings about assisting victims of IPV. METHOD: In 1998, a total site sample of 150 physicians practicing in a large general hospital in the area of Virginia Beach, Virginia, was surveyed by questionnaire via the mail. Four specialties were represented: emergency medicine, family practice, obstetrics-gynecology, and psychiatry. The questionnaire asked about medical training and training in assisting victims of IPV. The physicians' feelings about working with victims of IPV were measured on a nine-item, five-point semantic differential scale. RESULTS: A total of 76 physicians responded to the questionnaire (response rate = 51%). Only a minority (11%) had overall positive feeling scores about assisting victims of IPV. While most physicians reported that it was "significant work," the great majority also felt that it was difficult, low-paying, and stressful. Training in assisting victims of IPV, in medical school or afterwards, did not appear to influence feelings about assisting victims of IPV. However, physicians who were white and who were married (the majority of the respondents) were significantly more likely than the other respondents to feel negatively about providing services to victims of IPV. CONCLUSION: Graduate medical education and training programs need to address the association of negative feelings with helping women harmed by IPV, because these feelings may interfere with the appropriate screening, referral, and treatment of these victims.

A comparison of a 30-cluster survey method used in India and a purposive method in the estimation of immunization coverages in Tamil Nadu.

A 30-cluster survey method that is employed for estimating immunization coverages by the Government of India (GOI) was compared with a Purposive method, to investigate whether the likely omission of SC/ST and backward classes in the former would lead to the reporting of higher coverages. The essential difference between the two methods is in the manner in which the first household is selected in the chosen first stage sampling units (villages). With the GOI method, it is often close to the village centre, whereas with the Purposive method it is always in the periphery or in a pocket consisting of SC/ST or backward classes. A concurrent comparison of the two methods in three districts in Tamil Nadu showed no real differences in the coverage with DPT and BCG vaccines. However, the coverage was consistently higher by the GOI method in the case of the Polio vaccine (by 1.5%, 3.1% and 5.3% in the 3 districts), and the Measles vaccine (by 4.8%, 13.3% and 13.9%); the average difference was 3.3% for Polio vaccine (p = 0.08) and 7.3% for Measles vaccine (p = 0.01).

Investigation of flow behaviour of coal particles in a pilot-scale fluidized bed gasifier (FBG) using radiotracer technique.

Knowledge of residence time distribution (RTD), mean residence time (MRT) and degree of axial mixing of solid phase is required for efficient operation of coal gasification process. Radiotracer technique was used to measure the RTD of coal particles in a pilot-scale fluidized bed gasifier (FBG). Two different radiotracers i.e. lanthanum-140 and gold-198 labeled coal particles (100 gm) were independently used as radiotracers. The radiotracer was instantaneously injected into the coal feed line and monitored at the ash extraction line at the bottom and gas outlet at the top of the gasifier using collimated scintillation detectors. The measured RTD data were treated and MRTs of coal/ash particles were determined. The treated data were simulated using tanks-in-series model. The simulation of RTD data indicated good degree of mixing with small fraction of the feed material bypassing/short-circuiting from the bottom of the gasifier. The results of the investigation were found useful for optimizing the design and operation of the FBG, and scale-up of the gasification process.

The epidemiology of stroke in the East Asian region: a literature-based review.

Stroke is a leading cause of morbidity and mortality in the developed world. Our objective was to review comparable studies of stroke incidence, prevalence, and subtypes in the East Asian region. English language epidemiologic studies of stroke published from 1984 through 2004 were identified for the East Asian region (China, Hong Kong, Taiwan, Japan, North and South Korea and the ASEAN countries). The Sudlow-Warlow criteria were modified to identify comparable studies. Stroke epidemiology is relatively well characterized in China, Taiwan, and Japan; however, little information is available for other countries. Four studies of stroke incidence, from China, Taiwan, and Japan, were identified, which reported a total of 4995 first-ever stroke events. There was an over twofold difference in the age-adjusted incidence of stroke between the Chinese Seven Cities and Okinawa study (483 vs 201 per 100,000). The 1-month case fatality rate ranged from 12.7% to 17.3%. Only one population-based study on stroke prevalence, from Taiwan, was identified: Studies show the relatively high proportion of hemorrhagic stroke (30%). Stroke epidemiology is relatively well characterized in China, Japan, and Taiwan but not in other countries in the region. More recent data are needed to monitor stroke prevention efforts and guide planning of health care resources in the region.

Salicylate inhibits the translation and transcription of ompF in Escherichia coli.

OmpF is a major outer membrane protein in Escherichia coli whose expression is regulated by a large number of factors, including the osmolarity of the growth medium and the concentration of salicylate. We have previously shown that at low osmolarity, OmpF is post-transcriptionally regulated by micF mRNA, and that at high osmolarity, regulation occurs primarily by the inhibition of transcription by OmpR (Ramani et al. 1994). In contrast, salicylate was reported to alter OmpF expression solely by blocking translation primarily through micF mRNA (Rosner et al. 1991). We examined the effect of salicylate by analyzing the levels of OmpF in wild-type and micF strains grown with salicylate. At low concentrations of salicylate (0-4 mM), OmpF levels were inhibited strongly in wild-type cells, whereas no inhibition of OmpF was observed in the micF strain. At high concentrations of salicylate (10-20 mM), both the wild type and the micF strain showed strong inhibition of OmpF. To study the effect of salicylate on transcription, ompF mRNA and micF mRNA were analyzed in wild-type cells. micF mRNA levels increased during growth with 1, 2, and 4 mM salicylate. In contrast, ompF mRNA levels were not affected by low concentrations of salicylate, but decreased strongly at 10 and 20 mM salicylate. Taken together, these results suggest that similar to osmoregulation, salicylate inhibits both the translation and transcription of ompF.

Degradation and processing of cholecystokinin in guinea pig fundic gastric glands.

The degradation of 125I-CCK8 in guinea pig fundic gastric glands was time and temperature dependent. At both 24 and 37 degrees C, dithiothreitol (DTT) and chloroquine reduced the degradation of the internalized 125I-CCK8. After 60 min of binding, DTT, chloroquine and DTT plus chloroquine together significantly reduced radioligand degradation by 43, 55 and 66%, respectively, compared to control at 24 degrees C, and these differences remained significant after 1, 2 and 3 hr of processing. Similar effects were noted at 37 degrees C. About 75% of the radioactivity appearing in the supernatant after 60 min of exocytosis at 37 degrees C represented degraded material as measured by both Sep-Pak chromatography and rebinding methods. DTT and chloroquine both significantly reduced the amounts of degraded radioligand exocytosed from these glands.

micF antisense RNA has a major role in osmoregulation of OmpF in Escherichia coli.

micF RNA, produced from a multicopy plasmid, was originally shown to be a major factor in negative osmoregulation of the OmpF outer membrane protein in Escherichia coli. However, subsequent experiments with a micF deletion strain suggested that chromosomal micF RNA was not a key component in this process. We report here that micF RNA is essential for the reduction in OmpF levels in cells grown in media of low-to-intermediate levels of osmolarity. Under these conditions, the amount of OmpF was reduced up to 60% in the parent strain while OmpF levels were not altered in the micF deletion mutant. In medium of higher osmolarity, OmpF synthesis was strongly inhibited in both strains. RNA measurements showed that micF RNA levels rose rapidly in cells grown in low-to-intermediate levels of osmolarity concomitant with the reduction in OmpF protein, while ompF mRNA decreased strongly only during high-osmolarity conditions. Taken together, these results strongly suggest that the negative osmoregulation of OmpF at low-to-intermediate osmolarity levels requires micF RNA and that this is masked at higher osmolarity by the known strong inhibition of OmpF transcription by OmpR. Results consistent with this model were also obtained by using procaine, a compound reported to inhibit ompF expression by a mechanism very similar to that involved in osmoregulation.

In vitro interactions of integration host factor with the ompF promoter-regulatory region of Escherichia coli.

Previous work has shown that integration host factor (IHF) mutants have increased expression and altered osmoregulation of OmpF, a major Escherichia coli outer membrane protein. By in vitro analysis the possibility was investigated that IHF interacts directly with the ompF promoter region. Gel retardation assays and DNase I protection experiments showed that IHF binds to two sites in the ompF promoter region centered at positions -180 and -60 relative to the start of transcription. Gel electrophoresis studies with circularly permuted ompF promoter fragments indicated that IHF binding strongly increased a small intrinsic bend in the ompF promoter region. The addition of IHF to a purified in vitro transcription system strongly and specifically inhibited ompF transcription. This inhibition was reversed by increasing the concentration of OmpR, a positive activator required for ompF expression, suggesting that IHF may inhibit ompF transcription by altering how OmpR interacts with the ompF promoter.

Analysis of the proteins and cis-acting elements regulating the stress-induced phage shock protein operon.

The phage shock protein operon (pspABCE) of Escherichia coli is strongly induced by adverse environmental conditions. Expression is controlled principally at the transcriptional level, and transcription is directed by the sigma factor sigma 54. PspB and PspC are required for high-level psp expression during osmotic shock, ethanol treatment and f1 infection, but heat-induced expression is independent of these proteins. We report here that the promoter region contains an upstream activation sequence (UAS) that is required for psp induction and has the enhancer-like ability to activate at a distance. A DNA-binding activity is detected in crude protein extracts that is dependent on the UAS and induced by heat shock. We further show that integration host factor (IHF) binds in vitro to a site between the UAS and sigma 54 recognition sequence. In bacteria lacking IHF, psp expression is substantially reduced in response to high temperature and ethanol. During osmotic shock in contrast, psp expression is only weakly stimulated by IHF, and IHF mutants can strongly induce the operon. The dependence of psp expression on IHF varies with the inducing condition, but does not correlate with dependence on PspB and PspC, indicating distinct, agent-specific activation mechanisms.

Triiodothyronine receptors in porcine granulosa cells.

Triiodothyronine has been found to enhance gonadotropin- and insulin-stimulated morphologic luteinization and progesterone production by porcine granulosa cells in culture. The role of triiodothyronine in the above events is not well defined. One possibility is that triiodothyronine effects are direct and are receptor mediated. To test this concept, we undertook this study to investigate the presence of triiodothyronine receptors in granulosa cells aspirated from large (6 to 12 mm), medium (3 to 5 mm), and small (1 to 2 mm) porcine ovarian follicles. Crude nuclei were isolated and tested for iodine 125-triiodothyronine specific binding. Binding was time and temperature dependent and maximal in cells from small follicles at pH 8. Scatchard analysis yielded a mean apparent dissociation constant of 5.5 X 10(-9) mol/L and a mean apparent total number of binding sites of 1.0 pmol/mg of deoxyribonucleic acid. Competition experiments revealed the following relative binding affinities: triiodothyronine greater than L-thyroxine greater than reverse triiodothyronine. Gonadotropins, prostaglandins, epidermal growth factor, and insulin did not compete with 125I-triiodothyronine for binding. We conclude that there are nuclear binding sites in porcine granulosa cells with characteristics expected of a triiodothyronine receptor which might mediate a direct action of triiodothyronine on granulosa cells.