Biomedical subjects

W Tao

Publications and source records attributed to W Tao.

At least 73 records · Page 4Linked to original sources

PubMed1997

Endothelin receptor-mediated Ca2+ signaling and isoform expression in bovine corneal epithelial cells.

PURPOSE: Bovine corneal epithelial cells (BCEC) were cultured to determine whether endothelin (ET) receptor subtype stimulation affects ET isoform expression (ET-1, ET-2, and ET-3) through capacitative Ca2+ influx. To probe in the isolated bovine corneal epithelium (BCE) for ET isoform and ET (i.e., ETA and ETB) receptor gene expression. METHODS: [Ca2+]i transients were characterized with microfluorometry. Endothelin isoform and ET receptor gene expression were probed with RNase protection analysis. Enzyme-linked immunosorbent assay was used to measure levels of ET-1-like immunoreactivity (ET-1-LI) in conditioned medium. RESULTS: ET-1 (10(-6) M) increased [Ca2+]i more than twofold. After treatment with 10(-7) M alltrans retinoic acid (an inducer of differentiation), 10(-6) M sarafotoxin (S-6-c) (a selective ETB agonist), had a similar effect. Preincubation with either 5 microM U73122 (an inhibitor of IP8 formation) or 10 microM cyclopiazonic acid, which depletes intracellular Ca2+ store content, eliminated ET agonist-mediated [Ca2+]i increases. With a nominally Ca(2+)-free solution containing 10 microM cyclopiazonic acid, simultaneous 10(-6) M ET-1 and extracellular Ca2+ additions transiently increased [Ca2+]i twofold, whereas 10(-6) M S-6-c increased it by only 20%. This augmentation was eliminated by preexposure to either BQ123 (10 microM), selective ETA receptor antagonist, U73122 (5 microM), or SKF 96365 (3 x 10(-5) M), an inhibitor of stores-operated channels. ET-1, ET-2 isoforms, and ET receptor mRNAs were identified. S-6-c (10(-6) M) increased the level of ET-1-LI after 12 hours by approximately ninefold. CONCLUSIONS: In BCEC, capacitative calcium influx is involved in mediating a positive feedback relationship between ETB receptor stimulation and ET protein expression. Identification of ET-1 and ET-2 gene expression in BCE strengthens the notion that this regulation could be autocrine mediated.

Amino Acid Sequence↗

PubMed1997

Pathological classification and diagnosis of intestinal duplication.

OBJECTIVE: To determine the pathological classification and the clinical characteristics of intestinal duplication. METHODS: Eighty-four pediatric patients with intestinal duplication were proved on operation in the last 20 years in the Second Hospital of Harbin Medical University and Harbin Children's Hospital. The pathological classifications were as follows: enteral septum type (2), parietal cyst type (9), parenteral canal type (31), parenteral cyst type (35), and solitary type (1). The clinical presentations and complications included: abdominal mass (24), illius (41), hemorrhage of digestive tract (15) and intestinal perforation with peritonitis (3). Two asymptomatic cases were discovered incidentally. RESULTS: Among the 84 patients, 82 healed, 1 newborn complicated by intestinal fistula died of septicemia, and the other one died of toxic shock. CONCLUSIONS: Recognizing the pathological types, common presentations and complications, and applying the corresponding examination methods timely, doctors may improve the diagnostic accuracy.

Adolescent↗

PubMed1997

[Detecting pathogens of fetal defects in paraffin embedded tissues by polymerase chain reaction].

OBJECTIVE: To examine 3 types of pathogens in dead fetus with congenital defects for exploring the pathogenesis. METHODS: The paraffin embeded brain and liver tissues from 39 fetal autopsies with congenital defects were examined for toxoplasma, cytomegalovirus, and herpes simplex II by polymerase chain reaction. Among them 16 placentae were examined as well. RESULTS: Pathogens were detected in 25 of 39 cases, a positive rate of 64%. Nine out of the 13 fetuses with urogenital defects were positive for the shove pathogens, while 8 from the 12 with neural tube defects were positive as well. CONCLUSION: Intrauterine infection was one of the important causes of birth defects. The characteristics of placenta morphologic changes were described, and the significance of placenta investigation in congenital malformation was emphasized.

Animals↗

PubMed1996

The CD43 130-kD peripheral T-cell activation antigen is downregulated in thymic positive selection.

Specific glycoforms of CD43, the major O-glycosylated cell-surface protein on T lymphocytes, can affect cell adhesion according to the types of carbohydrate side chains carried. In the peripheral immune system, CD43 130 kD, which carries core 2 O-glycan structures on its surface, is an activation antigen expressed on both CD4 and CD8 single-positive (SP) T cells. We have previously shown that the 115-kD resting and 130-kD activation glycoforms of murine CD43 are differentially regulated on peripheral SP T cells. In this study, we used transgenic mice expressing T-cell receptors (TCRs) specific for antigens presented by class I and class II major histocompatibility complex (MHC) molecules to determine whether CD43 glycoforms are involved in thymocyte differentiation. Positive selection in these mice results in an increase in the production of CD8 and CD4 SP T cells, respectively, which express the transgenic TCR. Positive selection is also accompanied by the upregulation of TCR, CD69, and CD5. Using these markers to define stages of thymocyte maturation, we found that CD43 130 kD was downregulated in the positive selection of CD4 CD8 double-positive thymocytes expressing a class I but not class II MHC-restricted TCR. These data suggest that core 2 glycosyltransferase (C2GnT) modulated expression of CD43 glycoforms may be involved in thymic selection events.

Animals↗

PubMed1996

Transition state structure of Salmonella typhimurium orotate phosphoribosyltransferase.

Orotate phosphoribosyltransferase (OPRTase) catalyzes the magnesium-dependent conversion of alpha-D-phosphoribosylpyrophosphate (PRPP) and orotate to orotidine 5'-monophosphate (OMP) and pyrophosphate. We have determined kinetic isotope effects on the reaction of OMP with pyrophosphate and with the pyrophosphate analog phosphonoacetic acid. In the latter case, full expression of the kinetic isotope effects allowed us to calculate the structure of the transition state for the pyrophosphorylytic reaction. The transition state resembles a classical oxocarbonium ion. Using the recently reported three-dimensional structures of the OPRTase-OMP (Scapin et al., 1994) and the OPRTase-PRPP complexes (Scapin et al., 1995a), we have modeled the calculated transition state structure into the active site of OPRTase. We propose a detailed chemical mechanism which is consistent with these results.

Carbon Radioisotopes↗

PubMed1996

Characterization of the structure and function of the gene for transcription factor BF-1, an essential regulator of forebrain development.

Brain factor-1 (BF-1) is a winged-helix transcription factor which has been shown to be essential for the development of the cerebral hemispheres. We report here the cloning and characterization of the mouse BF-1 gene. We have identified two classes of alternatively spliced mouse BF-1 cDNA which are transcribed from distinct promoters. Both classes of cDNA encode identical BF-1 proteins. The class 1 mouse cDNA is the homolog of the previously reported rat and human BF-1 cDNAs, and accounts for about 90-95% of BF-1 expression in brain. Primer extension analyses show that the major promoter, P1, is TATA-less and has multiple transcription start sites. We identified neural cell lines which express BF-1 primarily from the P1 promoter, including the OBL21a and OBL21 cell lines derived from the olfactory bulb. Expression of BF-1 is highest in proliferating OBL21 cells, declining as the cells differentiate in vitro. This correlates well with the reduction of BF-1 expression as the cells of the telencephalic neuroepithelium differentiate. Using these cells, we demonstrate that the genomic region between -3.7kb and -79 bp upstream of the P1 promoter contains cell-specific enhancer activity in transient transfection assays.

Animals↗

PubMed1996

Correction of blood pH attenuates changes in hemodynamics and organ blood flow during permissive hypercapnia.

OBJECTIVES: To determine whether changes in cardiac output, regional blood flow, and intracranial pressure during permissive hypercapnia are blood pH-dependent and can be attenuated by correction of intravascular acidemia. DESIGN: Prospective, controlled study. SETTING: Research laboratory. SUBJECTS: Female Marino ewes. INTERVENTIONS: Animals were instrumented with a pulmonary artery catheter, femoral arterial and venous catheters, a catheter in the third cerebral ventricle, and ultrasonic flow probes on the left carotid, superior mesenteric, and left renal arteries 1 wk before experimentation. At initiation of the protocol, ewes underwent endotracheal intubation and mechanical ventilation under general anesthesia. Minute ventilation was reduced to induce hypercapnia with a target PaCO2 of 80 torr (10.7 kPa). In the pH-uncorrected group (n = 6), arterial blood pH was allowed to decreased without treatment. In the pH-corrected group (n = 5), 14.4 mEq/kg of sodium bicarbonate was given intravenously as a bolus to correct arterial blood pH toward a target arterial pH of 7.40 (dose calculated by the Henderson-Hasselbalch equation). MEASUREMENTS AND MAIN RESULTS: Arterial blood pH, PCO2, cardiac output, intracranial pressure, and carotid, superior mesenteric, and renal artery blood flow rates were measured at normocapnic baseline and at every hour during hypercapnia for 6 hrs. In the pH-uncorrected group, arterial blood pH decreased from 7.41 +/- 0.03 at normocapnia to 7.14 +/- 0.01 (p < .01 vs. normocapnia) as blood PCO2 increased to 81.2 +/- 1.8 torr (10.8 +/- 0.2 kPa). In the pH-corrected group, arterial blood pH was 7.42 +/- 0.02 at normocapnia and was maintained at 7.37 +/- 0.01 while PaCO2 was increased to 80.3 +/- 0.9 torr (10.7 +/- 0.1 kPa). Significant increases in cardiac output occurred with the initiation of hypercapnia for both groups (pH-uncorrected group: 4.3 +/- 0.6 L/min at normocapnia vs. 6.8 +/- 1.0 L/min at 1 hr [p < .05]; pH-corrected group: 4.1 +/- 0.4 at normocapnia vs. 5.7 +/- 0.4 L/min at 1 hr [p < .05]). However, this increase was sustained only in the uncorrected group. Changes in carotid and mesenteric artery blood flow rates, as a percent of baseline values, showed sustained significant increases in the pH-uncorrected groups (p < .05) and only transient (carotid at 1 hr) or no (superior mesenteric) significant change in the pH-corrected groups. Conversely, significant increases in renal artery blood flow were seen only in the pH-uncorrected group during the last 2 hrs of the experiment (p < .05). Organ blood flow, as a percent of cardiac output, did not change significantly in either group. Intracranial pressure increased significantly in the pH-uncorrected group (9.0 +/- 1.5 mm Hg at normocapnia vs. 26.8 +/- 5.1 at 1 hr, p < .05), and remained increased, while showing no significant change in the pH-corrected group (8.5 +/- 1.6 mm Hg at normocapnia to 7.7 +/- 4.2 at 1 hr). CONCLUSIONS: Acute hypercapnia, induced within 1 hr, is associated with significant increases in cardiac output, organ blood flow, and intracranial pressure. These changes can be significantly attenuated by correction of blood pH with the administration of sodium bicarbonate, without adverse effects on hemodynamics.

Acute Disease↗

PubMed1996

Therapeutic hyperthermia.

Those diseases that medicines do not cure, are cured by the knife, and those diseases that the knife cannot cure are cured by fire. And those diseases that fire does not cure are to be reckoned wholly incurable.

HIV Infections↗

PubMed1996

[The relationship between placental pathology and certain pathogens detected in paraffin-embedded tissues in cases of intrauterine growth retardation].

OBJECTIVE: To study the relationship between placental pathology and certain pathogens detected in paraffin-embedded placental tissues in cases of intrauterine growth retardation (IUGR). METHODS: The PCR-DNA techniques were used for determination of pathogens, including toxoplasma, cytomegalovirus and herps simplex type II in paraffin-embedded placental tissues from 53 cases of IUGR. RESULTS: Among 53 cases of IUGR, the pathogens were detected in 19 cases (35.85%). The relationships of pathogens detected to placental pathology were analyzed. Pathogens were found in 10 of 18 placentas with villitis, 7 of 11 placentas with villous maturation retarded and 2 of 3 intervillous space infections respectively. The incidence of infection in the pathological placentas was 59.38%. CONCLUSIONS: The study suggested that the haematogenous infections could play important roles in unknown causes of IUGR.

Adult↗

PubMed1995

Monomeric bovine IgG2 is a potent stimulus for bovine neutrophils.

Bovine plasma contains factors that can stimulate bovine neutrophils. Bovine plasma at 1:1,000,000-1:1,000 dilution induced a dose-dependent superoxide production in bovine neutrophils. When bovine plasma was fractionated with a protein G column, only the IgG fraction contained induction activity. At similar concentrations purified IgG induced a much stronger response than that of plasma IgG. Purified monomeric bovine IgG induced a dose-dependent increase in superoxide production. The maximum induction can be achieved at 100 micrograms/ml of bovine IgG. When subclasses of bovine IgG were examined, monomeric bovine IgG2 potently stimulated bovine polymorphonuclear leukocytes. In contrast, bovine IgG 1 failed to induce a response at similar concentrations, and neither bovine IgG F(ab')2 and Fc were effective. Both recombinant bovine granulocyte-macrophage colony-stimulating factor (r-BoGM-CSF) and recombinant bovine granulocyte colony-stimulating factor (r-BoG-CSF) primed bovine neutrophils for superoxide production induced by bovine IgG. The above results suggest that: (1) bovine plasma contain factors that can activate bovine neutrophils; (2) bovine plasma IgG is the major component that is responsible for bovine neutrophil activation; (3) bovine plasma contains factors that can inhibit the effect of bovine IgG; (4) monomeric bovine IgG2, but not IgG1, can activate bovine neutrophils directly without Fc receptor cross-linkage; (5) the integrity of bovine IgG is important in bovine polymorphonuclear leukocyte activation; and (6) bovine neutrophil activation induced by bovine IgG can be primed by r-BoGM-CSF or r-BoG-CSF.

Animals↗

PubMed1995

Winged helix transcription factor BF-1 is essential for the development of the cerebral hemispheres.

We generated mice with a null mutation of the forebrain-restricted transcription factor BF-1 to examine its function in brain development. Heterozygous animals have an apparently normal phenotype. Homozygous null BF-1 mutants die at birth and have a dramatic reduction in the size of the cerebral hemispheres. The development of the ventral telencephalon is more severely affected than that of the dorsal telencephalon. Telencephalic neuroepithelial cells are specified in the BF-1 mutant, but their proliferation is reduced. Dorsal telencephalic neuroepithelial cells also differentiate prematurely, leading to early depletion of the progenitor population. These results suggest that BF-1 controls the morphogenesis of the telencephalon by regulating the rate of neuroepithelial cell proliferation and the timing of neuronal differentiation.

Animals↗

PubMed1995

Gut mucosal ischemia during normothermic cardiopulmonary bypass results from blood flow redistribution and increased oxygen demand.

Impaired gut mucosal perfusion has been reported during cardiopulmonary bypass. To better define the adequacy of gut blood flow and oxygenation during cardiopulmonary bypass, we measured overall gut blood flow and ileal mucosal flow and their relationship to mucosal pH, mesenteric oxygen delivery and oxygen consumption in immature pigs (n = 8). Normothermic, noncross-clamped, right atrium-to-aorta cardiopulmonary bypass was maintained at 100 ml/kg per minute for 120 minutes. Animals were instrumented with an ultrasonic Doppler flow probe on the superior mesenteric artery, a mucosal laser Doppler flow probe in the ileum, and pH tonometers in the stomach, ileum, and rectum. Radioactive microspheres were injected before and at 5, 60, and 120 minutes of cardiopulmonary bypass for tissue blood flow measurements. Overall gut blood flow significantly increased during cardiopulmonary bypass as evidenced by increases in superior mesenteric arterial flow to 134.1% +/- 8.0%, 137.1% +/- 7.5%, 130.3% +/- 11.2%, and 130.2% +/- 12.7% of baseline values at 30, 60, 90, and 120 minutes of bypass, respectively. Conversely, ileal mucosal blood flow significantly decreased to 53.6% +/- 6.4%, 49.5% +/- 6.8%, 58.9% +/- 11.6%, and 47.8% +/- 10.0% of baseline values, respectively. Blood flow measured with microspheres was significantly increased to proximal portions of the gut, duodenum and jejunum, during cardiopulmonary bypass, whereas blood flow to distal portions, ileum and colon, was unchanged. Gut mucosal pH decreased progressively during cardiopulmonary bypass and paralleled the decrease in ileal mucosal blood flow. Mesenteric oxygen delivery decreased significantly from 67.0 +/- 10.0 ml/min per square meter at baseline to 42.4 +/- 4.6, 44.9 +/- 3.5, 46.0 +/- 3.6, and 42.9 +/- 3.9 ml/min per square meter at 30, 60, 90, and 120 minutes of bypass. Despite the decrease in mesenteric oxygen delivery, mesenteric oxygen consumption increased progressively from 10.8 +/- 1.4 ml/min per square meter at baseline to 13.4 +/- 1.2, 15.9 +/- 1.2, 16.7 +/- 1.4, and 16.6 +/- 1.54 ml/min per square meter, respectively. We conclude that gut mucosal ischemia during normothermic cardiopulmonary bypass results from a combination of redistribution of blood flow away from mucosa and an increased oxygen demand.

Analysis of Variance↗

PubMed1995

ETB and epidermal growth factor receptor stimulation of wound closure in bovine corneal epithelial cells.

PURPOSE: To determine if there is a heterogeneous pattern of endothelin (ET) receptor subtype (i.e., ETA and ETB) gene expression in the bovine corneal epithelium (BCE). To determine if ET receptor subtype stimulation increases the effectiveness of epidermal growth factor (EGF) to accelerate wound closure in a primary culture of bovine corneal epithelial cells (BCEC). METHODS: In situ hybridization histochemistry was used to characterize ETA and ETB gene expression in the BCE. A wound closure assay evaluated wound healing rates in BCEC after 4 to 7 days in culture. [3H] thymidine incorporation and MTT assay measured proliferation. RESULTS: ETA gene expression was appreciably higher in the basal cells than in the suprabasal cells, whereas the pattern for ETB was reversed. Epidermal growth factor (5 ng/ml) maximally increased wound closure by 145% above the control. With 5 ng/ml EGF, either 10(-9) M ET-1 or 10(-8) M sarafotoxin-6-c (s-6-c) increased wound closure by an additional 39% (P < 0.001) above that measured with 5 ng/ml EGF alone. BQ123 (10(-7) M) did not alter any of these effects of ET-1 or s-6-c. Epidermal growth factor stimulated wound closure through a selective increase in proliferation. Neither ET-1 nor s-6-c alone had any effect on proliferation or migration. CONCLUSIONS: Both ETA and ETB genes are expressed in BCE. However, in BCEC only, ETB stimulation increases the effectiveness of EGF to stimulate wound closure. This response was caused by an increase in cell migration rather than proliferation because, after treatment with mitomycin C, neither ET-1 nor EGF stimulated wound closure.

Animals↗

PubMed1995

[Stereoptical study of the microvilli in intrauterine growth retardation placenta with different ponderal indexes].

Two groups of 6 intrauterine growth retardation (IUGR) placentae each from normal ponderal index (NPI) or low ponderal index (LPI) and 10 placentae from normal pregnancy as control were quantitatively analyzed with light and electron microscopic morphometry. The results showed that the placental weight, volume, surface area of the villi and villous fetal capillary in IUGR were significantly reduced compared with those in the control group. Not only were the placental weight, volume, surface area of villi, villous capillary, intermicrovillous surface density and absolute values surface area of the microvilli in NPI group significantly lower than that in the control group, but also lower than in LPI group. This suggests that there was a functional deficiency of placenta in IUGR placentae, nonetheless, the changes of functional structures in IUGR placentae with different ponderal indexes were not the same. The stereoptical study with light microscopy and with the electron microscopic level in confirming that NPI group has a more severe deficiency in placental function than in the LPI.

Anthropometry↗

PubMed1995

[The pathological investigations on termination of early pregnancy with mifepristone].

133 samples of induced early abortions using mifepristone (RU486) in combination with misoprostol (Miso) were examined. There were no significant difference in the outcome and pathological changes between the two groups with varied RU486-Miso dosages. Another 133 samples of abortus (gestational age < or = 49 days) from vacuum aspiration were used as control. The villi of RU486-Miso group showed more extensive and severer degeneration than the villi of the control group under light and electron microscopy. However, whether RU486 affects the trophoblasts directly or in directly is yet in dispute. Further investigation is needed.

Abortion, Induced↗

PubMed1994

Transition state structures for the hydrolysis of alpha-D-glucopyranosyl fluoride by retaining and inverting reactions of glycosylases.

Secondary tritium and primary 14C kinetic isotope effects were measured for the hydrolysis of alpha-D-glucopyranosyl fluoride catalyzed by sugar beet seed alpha-D-glucosidase, forming alpha-D-glucose, and by Rhizopus niveus glucoamylase forming beta-D-glucose. The data provided a novel opportunity to model and directly compare the transition state structures for the hydrolysis of a substrate promoted with retention or inversion of configuration according to the enzyme catalyst. The isotope effects for the reaction catalyzed by each enzyme are most consistent with an SN1 rather than an SN2 mechanism. The modeled transition state structures for the hydrolysis promoted by the alpha-glucosidase and the glucoamylase both bear significant oxocarbonium ion character, with the D-glucosyl residue having a flattened 4C1 conformation and a C-1-O-5 bond order of 1.92, even though opposite D-glucose anomers were produced from the substrate. The transition states show some modest differences, but their general similarity strongly suggests that the stereochemical outcome of glycosylase reactions does not predict the transition state structure, nor does the transition state structure of such reactions predict the stereochemical outcome. The results support previously reported evidence for the separate topological control of product configuration by protein structures in these and other glycosylases.

Catalysis↗

PubMed1994

The T cell receptor repertoire of CD4-8+ thymocytes is altered by overexpression of the BCL-2 protooncogene in the thymus.

The bcl-2 gene encodes an intracellular, membrane-associated protein that protects immature cortical thymocytes from a wide variety of apoptotic stimuli, including glucocorticoids, radiation, and anti-CD3 treatment. Since cortical thymocytes are the primary target cells for thymic positive and negative selection processes, and since these processes are associated with cell death, we evaluated the role of bcl-2 in T cell development in two ways. In the first approach, transgenic mice expressing high levels of Bcl-2 in cortical thymocytes were mated with H-Y T cell receptor (TCR) transgenic mice, the latter being a well-defined system for the study of positive and negative selection of T cells. We found that the bcl-2 transgene had a dramatic effect on positive selection. This was manifested by a greatly increased production of mature thymocytes that were highly skewed towards the CD4-8+ lineage. The change involving CD4-8+ thymocytes occurred not only in bcl-2 transgenic mice, but was also observed in H-Y TCR/bcl-2 doubly transgenic mice, regardless of whether the H-Y TCR was expressed in the selecting (H-2b) or nonselecting (H-2d) environments. Furthermore, a large proportion of CD4-8+ thymocytes produced in H-2b H-Y TCR/bcl-2 doubly transgenic female mice expressed endogenous TCR alpha chains rather than the transgenic TCR alpha chain. These observations are consistent with the model that high expression of Bcl-2 in cortical thymocytes overrides the normal apoptotic pathway. This then allows the selection of CD4-8+ thymocytes expressing TCRs that are otherwise nonselectable. However, the bcl-2 transgene did not protect CD4+8+ thymocytes expressing the male-specific TCR from deletion in male doubly transgenic mice. In the second approach, we determined the level of bcl-2 mRNA expression in populations of thymocytes defined by their CD4/CD8 phenotypes using quantitative reversed transcriptase PCR techniques. Our results indicate that bcl-2 mRNA was expressed at a high level in immature CD4-8- thymocytes and in mature CD4+8- thymocytes. There is a dramatic downregulation of bcl-2 mRNA in CD4+8+ thymocytes, particularly those expressing a low level of TCR. CD4+8+ thymocytes that upregulated their TCR, likely as a result of receiving positive selection signals, also upregulated bcl-2 mRNA. This observation suggests that rescue of immature thymocytes from the programmed cell death pathway by positive selection signals is accompanied by the upregulation of bcl-2 mRNA.

Animals↗

PubMed1994

Expression of winged helix genes, BF-1 and BF-2, define adjacent domains within the developing forebrain and retina.

One of the earliest events in the development of the central nervous system is the establishment of positional identity along the anteroposterior (A-P) axis of the neuroepithelium. In recent years, regulatory genes with regionally restricted expression in the neuroepithelium have been identified which are believed to specify its developmental fate. We have previously described Brain Factor-1 (BF-1), a winged helix (WH) transcription factor expressed in the telencephalic neuroepithelium (Tao and Lai, 1992) Neuron 8:957-966. Here we report the cloning of the mouse cDNA for a novel WH protein, BF-2. We show that BF-2 is a sequence-specific DNA binding protein with a binding specificity distinct from BF-1. Its expression in the CNS during embryogenesis is restricted to the rostral diencephalic neuroepithelium. The caudal boundary of BF-2 expression is at the zona limitans intrathalamica. Rostrally, the BF-2 expression domain is adjacent to that of BF-1. The expression domains of these two factors define a boundary within the developing forebrain neuroepithelium. The BF-1/BF-2 boundary also extends laterally to divide the optic stalk and the retina into nasal (anterior) and temporal (posterior) domains. These observations suggest that in addition to playing a role in the subdivision of the forebrain, these two WH factors may also function to establish positional information in the retinal neuroepithelium.

Amino Acid Sequence↗