Isolation, characterization and expression of the human Factor In the Germline alpha (FIGLA) gene in ovarian follicles and oocytes

The Factor In the Germline alpha (FIGalpha) transcription factor regulates expression of the zona pellucida proteins ZP1, ZP2 and ZP3 and is essential for folliculogenesis in the mouse. Using the published mouse Figla sequence, BLAST searches identified a human chromosome 2 BAC clone with high sequence identity. Using PCR primers derived from this clone, amplicons derived from ovarian follicles and mature oocytes revealed 100% identity with the appropriate human BAC clone, the expected homology with the mouse Figla gene sequence, and homology on translation with the FIGalpha protein identified in the Japanese rice fish, medaka (Oryzias latipes). PCR expression profiling of this transcript revealed FIGLA mRNA expression in cDNA derived from ovarian follicles (5/5 samples from the primordial through to the secondary stage) mature oocytes (6/9 samples), and less frequently in preimplantation embryos (2/7 samples). Subsequent BLAST searches revealed the predicted full length coding sequence of the human FIGalpha protein which demonstrates 68 and 25% similarity overall to mouse and medaka proteins respectively, with 96 and 57% identity respectively within the basic helix-loop-helix region. This confirms our identification of the human homologue for this gene which maps to chromosome 2p12. Further work is required to understand its role in normal human oocyte development and the potential involvement in human infertility.

[Detection of the cutaneous melanomas, their metastasis and relapses by scintigraphies with 99MTC-HMPAO]

A pilot study was carried out in the Nuclear Medicine Department of the National Institute of Oncology and Radiobiology to learn the diagnostic efficacy of the 99mTc-HMPAO scintigraphy in the detection of cutaneous melanoma, distant and local metastases, in patients with a confirmed histological diagnosis. The planar and/or SPECT scintigraphy was performed in 17 patients and revealed 90% sensitivity for the detection of the disease. We calculated the tumor/background index in all the images obtained and found a value greater than 1 in every case. Thus, we can affirm that the 99mTc-HMPAO accumulation in tumors was higher than the background in all cases. We recommend that this procedure be considered in the follow up of these patients as a new diagnostic method which is very useful in the determination of the patient stage and prognostic evaluation.

The effect of enalapril on advanced diabetic nephropathy in African-American females

This paper examines the effect of enalapril in African-American (AA) females with advanced type 2 diabetic nephropathy (DN)--the leading cause of end stage renal disease (ESRD) in this group. AA females followed in our university nephrology clinic with type 2 DN and a serum creatinine level (Cr) > or = 2.5 mg/dl were eligible. Historical controls who never received an ACE inhibitor were selected (matched for age and Cr) from a database of patients reaching ESRD between 1993 and 1998, with a primary diagnosis of DN. Patients enrolled (N = 6) were started on enalapril at 5 mg per day with the dose titrated upward to a blood pressure (BP) goal of 140/90 mm Hg. The enalapril group tended to be older than controls (58.8 vs 51.5 years of age, P = ns) and had had their diabetes longer (18.5 vs 13.2 years of age, P = ns). At baseline, there were no significant differences in blood pressure, blood, urea, nitrogen (BUN), Cr, or BMI between groups. One of the 6 treated with enalapril had the agent stopped due to hyperkalemia. Five of 6 in the enalapril group reached ESRD, but there was no significant difference between the groups in the time it took to reach this stage (69.5 +/- 13.8 weeks vs 92.0 +/- 21.4 weeks, enalapril group vs control group, P = ns). In the enalapril patient who did not reach ESRD, the Cr level increased from 2.9 to 3.8 mg/dl in approximately 3 years. From this small study, we conclude that, although enalapril is tolerated in AA females with advanced DN, the agent had no significant effect on renal survival.

Low-dose theophylline does not exert its anti-inflammatory effects in mild asthma through upregulation of interleukin-10 in alveolar macrophages

BACKGROUND

There is accumulating evidence that theophylline has anti-inflammatory or immunomodulatory effects. This may be, in part, mediated via an upregulation in the production of the anti-inflammatory cytokine interleukin (IL)-10. We determined whether low-dose theophylline (LDT) would increase the production of IL-10, and attenuate the production of proinflammatory cytokines by alveolar macrophages.

METHODS

In a double-blind, placebo-controlled, crossover study involving 15 steroid-free patients with mild asthma, fiberoptic bronchoscopy and bronchoalveolar lavage (BAL) were performed at the end of the treatment and placebo periods. Alveolar macrophages were cultured in vitro, and we measured their release of IL-10, GM-CSF, and TNF-alpha. We also measured IL-10 production in whole blood together with the number of monocytes and T cells expressing intracellular IL-10 by flow cytometry.

RESULTS

LDT did not increase the production of IL-10, or attenuate the production of GM-CSF or TNF-alpha by alveolar macrophages. However, after theophylline treatment, there was a significant reduction in mean (SD) (95% CI) BAL eosinophil number from 3.4 (1.7)% (95% CI 2.4-4.4) to 1.7 (1.0)% (95% CI 1.1-2.3) compared with placebo (P<0.05). Similarly, there was no increase in whole-blood IL-10 release or in the number of monocytes and T cells expressing intracellular IL-10 after treatment.

CONCLUSIONS

LDT has an anti-inflammatory effect in asthma; however, this effect is not mediated via the production of IL-10 or the attenuation of GM-CSF or TNF-alpha. The mechanisms of theophylline activity remain to be determined.

Dynamic intrahepatic flow and cellular alterations during radiofrequency ablation of liver tissue in mice

PURPOSE

The purpose of this study was to identify microvascular and other associated changes that occur in the liver during focal heating with monopolar radiofrequency (RF).

MATERIALS AND METHODS

Intravital video microscopy was performed on exteriorized transilluminated livers of 15 live mice during RF-induced heating of liver parenchyma. Microvascular flow parameters, flow reversibility, microbubble formation, phagocytic activity, and endothelial permeability were recorded throughout a range of tip temperatures (40 degrees C-95 degrees C).

RESULTS

During RF application, five discrete zones extended outward from the electrode surface: (i) tissue coagulation, (ii) cellular edema/necrosis, (iii) sinusoidal stasis, (iv) parenchymal shunting, and (v) normal liver tissue. Reversal of stasis in sinusoids and small (<25 microm) vessels occurred at tip temperatures below 50 degrees C. This zone of stasis corresponded to the hyperemic zone on histologic analysis. Although alterations in permeability and phagocytic activity were first identified at 43 degrees C, tip temperatures higher than 55 degrees C always produced local endothelial leakiness to carbon microparticles at the periphery and always inhibited phagocytic activity. At tip temperatures higher than 95 degrees C, microbubble formation occurred with bubbles ultimately tracking through necrotic tissue into patent sinusoids. Larger peripheral vessels (>30 microm) limited extension of coagulation.

CONCLUSION

Although coagulation occurs at tip temperatures higher than 50 degrees C, RF heating induced reversible microvascular stasis at temperatures lower than 50 degrees C. Increased sinusoidal endothelial permeability occurs at near-coagulative temperatures. Therefore, targeted endovascular microparticle delivery through this leaky endothelium may provide an additional and complimentary adjunct for RF ablation therapy.

Increase in plasma esterified F2-isoprostanes following intravenous iron infusion in patients on hemodialysis

BACKGROUND

In epoetin-treated dialysis patients, currently iron is administered by the intravenous route to maintain optimum erythropoiesis. However, rapid infusion of iron in excess of transferrin binding capacity can lead to the availability of unbound iron that can theoretically catalyze peroxidation of lipids, such as low-density lipoprotein (LDL), which when oxidatively modified is proinflammatory and promotes atherogenesis.

METHODS

To address this issue, our study used one of the most specific measures of lipid peroxidation available, namely gas chromatography/mass spectometry (GC/MS) analysis of F2-isoprostanes. Using a prospective design, blood samples were collected 15 minutes before (pre) and 30 minutes after (post) a one-hour infusion of 700 mg bolus of intravenous iron in 22 adult home-hemodialysis patients on a non-hemodialysis day.

RESULTS

With iron-dextran infusion, serum iron markedly increased (mean +/- SE, 42 +/- 4 vs. 311 +/- 92 microg/dL, P < 0.0001) and exceeded the transferrin saturation of 100% in 22 out of 22 patients (pre 23 +/- 3 vs. post 165 +/- 8%, P < 0.0001). Plasma concentrations of free F2-isoprostanes did not change significantly following infusion of iron (pre 40 +/- 5 vs. post 39 +/- 6 pg/mL). However, levels of F2-isoprostanes esterified in plasma lipoproteins increased significantly in the postinfusion samples (pre 199 +/- 19 vs. post 233 +/- 25 pg/mL, P < 0.004). Pre-infusion levels of serum iron correlated directly with pre-infusion levels of esterified F2-isoprostanes (r = 0.56, P = 0.008), which persisted in the postinfusion period (r = 0.43, P = 0.04). However, there was no correlation between esterified F2-isoprostanes and serum ferritin levels. In the last four patients in whom blood samples were collected five hours after the intravenous iron infusion, there were further increases in esterified F2-isoprostanes that very closely correlated with postinfusion serum iron levels (r = 0.99, P = 0.013). In a control study, the in vitro addition of iron dextran to blood samples did not increase free or esterified F2-isoprostanes, suggesting that the increase in esterified F2-isoprostanes seen in vivo after iron infusion in patients is not due to a procedural artifact.

CONCLUSION

Collectively our data suggest that high levels of serum iron appearing soon after a large bolus of iron infusion is associated with significant, albeit modest, increases in levels of F2-isoprostanes esterified in plasma lipoproteins that tended to increase with time. Although it is uncertain whether this degree of lipid peroxidation may have deleterious effects, it may be sagacious to explore whether this can be prevented by slow infusion of frequent smaller doses of iron and, if necessary, along with administration of antioxidants.

Low-dose theophylline reduces eosinophilic inflammation but not exhaled nitric oxide in mild asthma

Theophylline is well-established in the management of asthma, and there is some evidence of an antiinflammatory effect in asthma. It is not known whether theophylline affects inflammatory markers such as sputum eosinophils and exhaled nitric oxide (NO) in patients with mild asthma not receiving inhaled steroid therapy. In a double-blind, placebo-controlled, cross-over study of 15 patients with mild asthma, we assessed the effect of low-dose theophylline therapy (250 mg twice per day) on eosinophils in induced sputum, bronchoalveolar lavage (BAL) and airway biopsies at the end of both the treatment and placebo periods. Measurements of exhaled nitric oxide (NO) were made at the end of the active and placebo treatment periods of 5 wk each. Low-dose theophylline (mean serum level, 6.1 mg/L) led to a significant reduction in mean (95% confidence interval [CI]) sputum eosinophils from 11.3% (7.80-14.76%) to 8.0% (5.46-10.44%), BAL eosinophils from 3.4% (2.4-4.4%) to 1.7% (1.1-2.3%) and biopsy eosinophils from 1.83% (0.76-2.89%) to 1.20% (0.27-2.13%) compared with placebo (all p < 0.05). There was no significant change in levels of exhaled NO or improvement in lung function and bronchial responsiveness. Low-dose theophylline induced antiinflammatory effects in asthma, reflected by a fall in airway eosinophils with no change in exhaled NO or changes in lung function.

[Pilot study with the monoclonal antibody IOR-C5 as a potential agent of radioimmunoscintigraphy in colorectal cancer]

IOR C-5 is a G1 immunoglobulin type intact murine monoclonal antibody (MAb) that was developed in the Center of Molecular Immunology in Havana City, Cuba. In immunohistochemical studies, this demonstrated a significant affinity for the epithelial tissues so that it was used in a pilot clinical study to perform a radioimmunoscintigraphy of the colorectal primary tumors and their locoregional recurrences. It was labeled with 99mTc using the Schwarz method, with a > 95% performance. Planar images of the chest, abdomen and pelvis were performed at 10 minutes, 4-6 hours and 18-24 hours post-injection in the anterior and posterior projections and the SPECT was performed 4-6 hours and 18-24 hours post-injection of 1.85 GBq 99mTC. This study has aimed to verify in vivo the capacity of ior-C5 MAb to accumulate in the malignant colorectal lesions. ior-C5 accumulated in 5 out of the 7 patients who were studied and who were suffering from colorectal cancer or in whom there was suspicion of recurrence. There was a negative case of primary tumors, which was an adenocarcinoma in situ in a tubular-papillary adenoma. The second case with a negative radioimmunoscintigraphy was a true negative case.

CONCLUSIONS

It can be concluded that even though the number of patients is quite low, ior-C5 fulfilled the expectations of recognizing the epitope expressed in colorectal tumors in an in vivo human environment.

Endstage renal disease owing to diabetic nephropathy in Mississippi: an examination of factors influencing renal survival in a population prone to late referral

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of endstage renal disease (ESRD) in the United States. We reviewed our experience with DN as a cause of ESRD in a predominantly poor, African American (AA) population.

METHODS

Charts of patients who entered the ESRD program through the University of Mississippi Medical Center with a primary diagnosis of DN from 1993 through 1998 were reviewed for factors that may affect renal survival. Time from initial clinic visit to entry into the ESRD program, or time to ESRD (TTE), was the primary end point.

RESULTS

Five hundred sixty-two patients entered the ESRD program (85% AA), and 210 of them had DN as their primary ESRD diagnosis. DN accounted for 50.5% of ESRD cases among AA females, but for less than 20% among AA males. In contrast, hypertension was the ESRD diagnosis in 48% of AA males. Patients observed in our nephrology clinic were analyzed further (n=171). At presentation, patients had advanced disease (serum creatinine [Cr]=5.92 mg/dL), were hypertensive, obese, and not likely to be on an angiotensin-converting enzyme (ACE) inhibitor. Determinants of TTE in univariate analysis were race (AA did better), initial blood urea nitrogen and plasma serum Cr levels, starting an ACE inhibitor at the University of Mississippi Medical Center, and the level of mean arterial pressure (MAP) during the course of follow-up. On multivariate analysis only initial Cr and race remained significant The 142 AA diabetics (111 female) were analyzed separately. The only significant sex difference was body mass index (female, 33.6 vs male, 28.4 kg/m2; P=0.0069), but females tended to have relatively shorter TTE and higher blood pressure (BP). Univariate and multivariate analyses revealed the same factors as above as determinants of TTE; however, among AAs, presenting on a calcium channel blocker was negatively correlated with TTE in univariate analysis. Among the entire cohort and the AAs, patients who had MAP between 100 and 110 mm Hg during the course of follow-up did better in terms of renal survival than those who fell outside of that range.

CONCLUSIONS

We conclude that AA females in Mississippi are significantly more predisposed to DN as a cause of ESRD than are AA males. Patients with DN in our population had poor BP control, presented to nephrologists with advanced disease, and often were not on an ACE inhibitor. The optimal level of BP control and which BP agents are best for this population need to be determined.

Drosophila OVO regulates ovarian tumor transcription by binding unusually near the transcription start site

Evolutionarily conserved ovo loci encode developmentally regulated, sequence-specific, DNA-binding, C(2)H(2)-zinc-finger proteins required in the germline and epidermal cells of flies and mice. The direct targets of OVO activity are not known. Genetic experiments suggest that ovo acts in the same regulatory network as ovarian tumor (otu), but the relative position of these genes in the pathway is controversial. Three OVO-binding sites exist in a compact regulatory region that controls germline expression of the otu gene. Interestingly, the strongest OVO-binding site is very near the otu transcription start, where basal transcriptional complexes must function. Loss-of-function, gain-of-function and promoter swapping constructs demonstrate that OVO binding near the transcription start site is required for OVO-dependent otu transcription in vivo. These data unambiguously identify otu as a direct OVO target gene and raise the tantalizing possibility that an OVO site, at the location normally occupied by basal components, functions as part of a specialized core promoter.

Characterization of a MEN1 ortholog from Drosophila melanogaster

Multiple endocrine neoplasia type 1 (MEN1) is a familial cancer syndrome characterized by tumors of the parathyroid, entero-pancreatic neuroendocrine and pituitary tissues and caused by inactivating mutations in the MEN1 gene. Menin, the 610-amino acid nuclear protein encoded by MEN1, binds to the transcription factor JunD and can repress JunD-induced transcription. We report here the identification of a MEN1 ortholog in Drosophila melanogaster, Menin1, that encodes a 763 amino acid protein sharing 46% identity with human menin. Additionally, 69% of the missense mutations and in-frame deletions reported in MEN1 patients appear in amino acid residues that are identical in the Drosophila and human protein, suggesting the importance of the conserved regions. Drosophila Menin1 gene transcripts use alternative polyadenylation sites resulting in 4.3 and 5-kb messages. The 4.3-kb transcript appears to be largely maternal, while the 5-kb transcript appears mainly zygotic. The binding of Drosophila menin to human JunD or Drosophila Jun could not be demonstrated by the yeast two-hybrid analysis. The identification of the MEN1 ortholog from Drosophila melanogaster will provide an opportunity to utilize Drosophila genetics to enhance our understanding of the function of human menin.

Gene discovery using computational and microarray analysis of transcription in the Drosophila melanogaster testis

Identification and annotation of all the genes in the sequenced Drosophila genome is a work in progress. Wild-type testis function requires many genes and is thus of potentially high value for the identification of transcription units. We therefore undertook a survey of the repertoire of genes expressed in the Drosophila testis by computational and microarray analysis. We generated 3141 high-quality testis expressed sequence tags (ESTs). Testis ESTs computationally collapsed into 1560 cDNA set used for further analysis. Of those, 11% correspond to named genes, and 33% provide biological evidence for a predicted gene. A surprising 47% fail to align with existing ESTs and 16% with predicted genes in the current genome release. EST frequency and microarray expression profiles indicate that the testis mRNA population is highly complex and shows an extended range of transcript abundance. Furthermore, >80% of the genes expressed in the testis showed onefold overexpression relative to ovaries, or gonadectomized flies. Additionally, >3% showed more than threefold overexpression at p <0.05. Surprisingly, 22% of the genes most highly overexpressed in testis match Drosophila genomic sequence, but not predicted genes. These data strongly support the idea that sequencing additional cDNA libraries from defined tissues, such as testis, will be important tools for refined annotation of the Drosophila genome. Additionally, these data suggest that the number of genes in Drosophila will significantly exceed the conservative estimate of 13,601.

Suppression of distinct ovo phenotypes in the Drosophila female germline by maleless- and Sex-lethal

Mutations in ovo result in several different phenotypes, which we show are due to the regulation of distinct developmental pathways. Two X (female) germ cells require ovo+ activity for viability, but 1X (male) germ cells do not. In our study, we observed suppression of the ovo germline-lethality phenotype in loss-of-function maleless (mle) females indicating that ovo+ and mle+ have opposing effects in female germ cells; or that they are hierarchically related. Gain-of-function Sex-lethal (Sxl) alleles and male specific lethal-2 alleles did not suppress the ovo germline death phenotype. Many of the surviving germ cells in females mutant for both ovo and mle showed ovarian tumors. In contrast to the germline viability phenotype, we did observe suppression of the tumor phenotype in females heterozygous for gain-of-function alleles of Sxl. Further, females mutant for some hypomorphic ovo alleles were rendered fertile by Sxl gain-of-function alleles. Thus, ovo+ is required for at least two distinct functions, one involving mle+, and one mediated by Sxl+ gene products. The existence of ovo+ functions independent of mle+ and Sxl+ is likely.

OVO transcription factors function antagonistically in the Drosophila female germline

OVO controls germline and epidermis differentiation in flies and mice. In the Drosophila germline, alternative OVO-B and OVO-A isoforms have a common DNA-binding domain, but different N-termini. We show that these isoforms are transcription factors with opposite regulatory activities. Using yeast one-hybrid assays, we identified a strong activation domain within a common region and a counteracting repression domain within the OVO-A-specific region. In flies, OVO-B positively regulated the ovarian tumor promoter, while OVO-A was a negative regulator of the ovarian tumor and ovo promoters. OVO-B isoforms supplied ovo(+) function in the female germline and epidermis, while OVO-A isoforms had dominant-negative activity in both tissues. Moreover, elevated expression of OVO-A resulted in maternal-effect lethality while the absence of OVO-A resulted in maternal-effect sterility. Our data indicate that tight regulation of antagonistic OVO-B and OVO-A isoforms is critical for germline formation and differentiation.

Recovery of hypopituitarism after neurosurgical treatment of pituitary adenomas

Surgery is the treatment of choice for many pituitary tumors; pituitary function may suffer after operation, but relief of pressure on the normal pituitary may also favor postoperative recovery of hypopituitarism. The aim of this study was to investigate the frequency of new appearance and recovery of hypopituitarism after neurosurgery and try to identify features associated with it. Pre- and postoperative anterior pituitary functions were investigated in 234 patients with pituitary adenomas (56 nonfunctioning, 71 PRL-secreting, 66 GH-secreting, 39 ACTH-secreting, 1 LH/FSH-secreting, and 1 TSH-secreting tumors). Eighty-eight new postoperative pituitary hypofunctions appeared in 52 patients (12 NF, 14 PRL-secreting, 15 GH-secreting, 10 ACTH-secreting, and 1 LH/FSH-secreting adenomas). They corresponded to 27% ACTH deficiencies (in 29 of the 107 patients with normal preoperative ACTH in whom postoperative evaluation was complete), 14.5% (15 of 103) new GH deficiencies, 10.5% (15 of 143; P < 0.0005, significantly less than ACTH deficiency) new TSH deficiencies, 16.5% (20 of 121) new gonadotropin deficiencies, and 13% (9 of 71) new PRL deficiencies. Preoperatively, 93 were deficient in at least 1 pituitary hormone; after surgery, 45 (48%) recovered between 1 and 3 hormones. The 2 patients with LH/FSH- and TSH-secreting macroadenomas did not recover pituitary function. Factors associated with a higher probability of postoperative pituitary function recovery were: no tumor rests on postoperative pituitary imaging (P = 0.001) and no neurosurgical (P = 0.001) or pathological evidence (P = 0.049) of an invasive nature. Tumor size did not differ significantly between those who did and those who did not recover pituitary function after surgery. Even if clear hypofunction is observed at initial work-up, patients should be reassessed after surgery without substitution therapy, because practically half the preoperative pituitary hormone deficiencies recover postoperatively, eliminating the need for life-long substitution therapy.

Genetic and environmental origins of verbal and performance components of cognitive delay in 2-year-olds

The authors investigated the etiology of several measures of cognitive delay. Verbal (V) and performance (P) abilities were assessed in over 3,000 pairs of 2-year-old twins. Group-differences heritability for general delay (the lowest 5% of the V and P composite) was 35%. However, V and P delays considered independently showed large differences in group heritability (77% for V vs. 40% for P). Specific delays with comorbid cases eliminated showed an even greater difference in group heritability (78% vs. 22%, respectively). The small sample comorbid for both V and P delay also yielded high group heritability for both V (77%) and P (93%) scores. Shared environmental factors also differed in magnitude for V (20%) and P (41%) delays. Because the genetic and environmental origins of V and P delays in infancy differ, they are better considered separately rather than combined into a composite measure of general cognitive delay.

Calcified microspheres as biological entities and their isolation from bone

Calcified microspheres, about 1 microm in diameter, appear at sites of bone formation where they invest the collagenous matrix, become confluent and disappear. Evidence that the particle boundaries are not lost with compaction but merely deformed is supported in section by the granular histochemical staining of the inorganic phase for bone salt, lipid, fibronectin and acid phosphatase in osteomalacic, acid-etched and normal human bone. Their persistence as discrete objects is confirmed by the application of methods for their isolation from the collagenous matrix of immature mouse calvarium and mature bovine femur. Five methods have been used to extract them and include (i) biochemical, (ii) chemical, (iii) mechanical, (iv) pyrogenous and (v) biological separation. Under the optical microscope, all isolates consisted of similar discrete objects and bridged assemblies, whose birefringence varied with treatment. After decalcification, their organic 'ghosts' remained. Each isolated microsphere had a complex substructure of clusters of non-collagenous calcified filaments surrounding a less dense centre. The filaments were 5 nm in diameter with a 5 nm periodicity and regular fine interfilamentous connections. It is concluded that the microspheres are independent, complex, pervasive and central to the containment (i.e. packaging) of calcium phosphate in bone. Their extraction will enable further analysis.

Response of Birds and Reptiles to Fire Regimes on Pastoral Land in the Victoria River District, Northern Territory

Birds and reptiles were censused at two sites of contrasting soil texture (clay, loam) on pastoral land in the Victoria River District, Northern Territory. Both sites comprised 16 plots (each of 2.6 ha) subjected to seven different experimental fire regimes (unburnt, burnt in the early dry season at 2, 4 and 6 year intervals, and burnt in the late dry season at 2, 4 and 6 year intervals) beginning five years before sampling (and thus, not all regimes had been operationally distinct between the onset of the experiment and this sampling). The regimes were deconstructed to four fire factors: the imposed regime, the time since last fire, the number of fires since the inception of the experiment, and the number of hot (=late dry season) fires. Of 30 species recorded from at least four plots, 12 were significantly associated with time since last fire. These responses were mostly to the extremes - some species were associated with the most recently burnt areas, and others occurred mainly in the plots which had been unburnt the longest. Longer- term responses to fire regimes were generally less clearcut, possibly because the relatively short duration of the imposed experimental fire treatments had not yet brought about substantial environmental divergence. Key words: fire regime, tropical savannas, birds, reptiles, diversity.

Genetic influence on language delay in two-year-old children

Previous work suggests that most clinically significant language difficulties in children do not result from acquired brain lesions or adverse environmental experiences but from genetic factors that presumably influence early brain development. We conducted the first twin study of language delay to evaluate whether genetic and environmental factors at the lower extreme of delayed language are different from those operating in the normal range. Vocabulary at age two was assessed for more than 3000 pairs of twins. Group differences heritability for the lowest 5% of subjects was estimated as 73% in model-fitting analyses, significantly greater than the individual differences heritability for the entire sample (25%). This supports the view of early language delay as a distinct disorder. Shared environment was only a quarter as important for the language-delayed sample (18%) as for the entire sample (69%).

Drosophila OVO zinc-finger protein regulates ovo and ovarian tumor target promoters

The ovo+ and ovarian tumor+ genes function in the germline sex determination pathway in Drosophila, but the hierarchical relationship between them is unknown. We found that increased ovo+ copy number resulted in increased ovarian tumor expression in the female germline and increased ovo expression in the male germline. The ovo locus encodes C2H2 zinc-finger proteins. Bacterially expressed OVO zinc-finger domain bound to multiple sites at or near the ovo and ovarian tumor promoters strongly suggesting that OVO is directly autoregulatory and that ovarian tumor is a direct downstream target of ovo in the germline sex determination hierarchy. Both positive and negative regulation by OVO proteins appears likely, depending on promoter context and on the sex of the fly. Our observation that two strong OVO-binding sites are at the initiator of the TATA-less ovo-B and ovarian tumor promoters raises the possibility that OVO proteins influence the nucleation of transcriptional pre-initiation complexes.