A locus for female discrimination behavior causing sexual isolation in Drosophila.

The genetic basis of sexual isolation that contributes to speciation is one of the unsolved questions in evolutionary biology. Drosophila ananassae and Drosophila pallidosa are closely related, and postmating isolation has not developed between them. However, females of both species discriminate their mating partners, and this discrimination contributes to strong sexual isolation between them. By using surgical treatments, we demonstrate that male courtship songs play a dominant role in female mate discrimination. The absence of the song of D. pallidosa dramatically increased interspecies mating with D. ananassae females but reduced intraspecies mating with D. pallidosa females. Furthermore, genetic analysis and chromosomal introgression by repeated backcrosses to D. pallidosa males identified possible loci that control female discrimination in each species. These loci were mapped on distinct positions near the Delta locus on the middle of the left arm of the second chromosome. Because the mate discrimination we studied is well developed and is the only known mechanism that prevents gene flow between them, these loci may have played crucial roles in the evolution of reproductive isolation, and therefore, in the speciation process between these two species.

Mate choice in Drosophila melanogaster and D. sechellia: criteria and their variation depending on courtship song.

Courtship song is one of the most important male signals in Drosophila mating. A female D. melanogaster copulates more readily when given a conspecific type of courtship song. Female D. melanogaster accepted winged D. sechellia more than wingless ones in a no choice test. Copulation frequencies varied between strains and were significantly correlated with male mating propensity of D. sechellia. Females from three of five strains of D. sechellia accepted winged D. melanogaster less than wingless ones in no choice tests, suggesting that D. melanogaster songs reduce mating in D. sechellia females. Multiple choice tests showed that males prefer conspecifics. In female choice tests, D. melanogaster females copulated with winged heterospecific D. sechellia males more than with wingless conspecific D. melanogaster males in the confined condition, suggesting that song differences between D. melanogaster and D. sechellia affect D. melanogaster females less than the absence of courtship song. Copyright 2000 The Association for the Study of Animal Behaviour.

Courtship song recognition in the Drosophila melanogaster complex: heterospecific songs make females receptive in D. melanogaster, but not in D. sechellia.

The courtship song emitted by male wing vibration has been regarded as one of the most important signals in sexual isolation in the species of the Drosophila melanogaster complex. Inter- and intraspecific crosses were observed using males whose wings were removed (mute) or females whose aristae were removed (deaf). Females of D. melanogaster, D. simulans, and D. mauritiana mated with heterospecific males in the song-present condition (cross between normal females and winged males) more often than in the no-song condition (cross between normal females and wingless males or between aristaless females and winged males) or they showed no preference between the two conditions. It is possible that in these females heterospecific courtship songs play a role as if they were conspecific. In contrast, the females of D. sechellia mated with D. melanogaster or D. simulans males in the no-song condition more often than in the song-present condition, suggesting that they reject males with heterospecific song. Female mate recognition depending on the courtship song in D. melanogaster, D. simulans, and D. mauritiana is considered to be relatively broader and that in D. sechellia narrower.

The P2 protein of rice dwarf phytoreovirus is required for adsorption of the virus to cells of the insect vector.

Intact particles of rice dwarf phytoreovirus adsorbed to and entered monolayer-cultured cells of the insect vector Nephotettix cincticeps and multiplied within the cells. Particles that lacked the P2 protein neither attached to nor infected such cells. Furthermore, P2-free particles obtained from a transmission-competent isolate of the virus were unable to infect insect vectors that had been allowed to feed on these virus particles through a membrane. However, when such virus particles were injected into insects via a glass capillary tube they successfully infected the insects, which became able to transmit the virus. These results support the hypothesis that, while P2-free particles can neither interact with nor infect cells in the intestinal tract of the insect vector, they do retain the ability to infect such cells when physically introduced into the hemolymph by injection.

Schwannoma of the penis: report of a case and review of the literature.

A case of schwannoma located in the penile shaft in a 65-year-old male is described. Special stain using S-100 immunoperoxidase was useful in establishing the diagnosis in this case. We reviewed the literature on penile schwannoma and focussed on the diagnosis of this rare ailment.

Pericentric inversion of chromosome 9 in infertile men.

Reproductive condition was studied in 6 infertile men with pericentric inversion of chromosome 9. Semen analyses revealed one azoospermia, one oligozoospermia, three asthenozoospermias and one normozoospermia. Four cases showed normal levels of plasma gonadotropins and testosterone. The response of plasma testosterone to human chorionic gonadotropin was within the normal range in all cases. However, the administration of LH-RH resulted in abnormal response of plasma gonadotropin in all patients. These results indicate that infertile males with pericentric inversion of chromosome 9 have an abnormality in the hypothalamic-pituitary-testicular axis.

Influence of adenine-induced chronic renal failure on testicular function in the rat.

The influence of adenine-induced chronic renal failure on the male reproductive function was investigated using male Wistar rats. Adenine-induced chronic renal failure was performed in 22 rats (adenine-treated) by providing them with an adenine-excessive diet (150 mg adenine per day) for 10 days. An additional 22 rats were fed without adenine-excessive diet and served as a control group. On days 30 and 60 after start of treatment, body weight ratio to the testis, serum levels of creatinine, urea nitrogen, luteinizing hormone (LH), follicle-stimulating hormone (FSH), 17 alpha hydroxyprogesterone (17 alpha-OHP), androstenedione and testosterone were measured. During the experiment, progressive elevation of serum creatinine and urea nitrogen was found in adenine-treated rats. Body weight ratio of the testes and serum level of LH in adenine-treated rats were similar to those in the controls. On day 60, the FSH level in adenine-treated rats was significantly higher than that in the controls (P < 0.001). While serum concentrations of 17 alpha-OHP and androstenedione in adenine-treated rats were considerably elevated compared with those in the controls on day 30 (P < 0.05). These concentrations did not differ between the two groups at day 60. Serum testosterone level was reduced in adenine-treated rats (P < 0.001). This reduction was progressive with time (P < 0.05). These results suggest that adenine itself reduces testosterone synthesis by suppressing 17 beta-hydroxysteroid oxidoreductase at the early stage of adenine-induced chronic renal failure, but that progressive renal insufficiency causes an elevation of FSH, a reduced synthesis of testosterone and its precursors at the late stage of adenine-induced chronic renal failure. Thus, hormonal conditions in the male rat with adenine-induced chronic renal failure change with time after induction.

Short-arm dicentric Y chromosome associated with Sertoli-cell-only tubule.

We report a case of a short-arm dicentric Y chromosome associated with Sertoli-cell-only tubule. Chromosomal analysis, using G- and C-banding techniques, revealed: 45,X/46,X psu dic(Y) (pter-->q11::q11-->pter)/46,X + mar. Staining by fluorescence in situ hybridization using a Y chromosome centromere-specific DNA probe showed two bright spots in the pseudodicentric Y chromosome and one in the marker chromosome. It is assumed that Sertoli-cell-only tubule is caused by deletion or disruption of the azoospermic factor gene located distal in Yq11.

The loss of outer capsid protein P2 results in nontransmissibility by the insect vector of rice dwarf phytoreovirus.

A transmission-defective (TD) isolate of rice dwarf phytoreovirus lacked the ability to infect cells when derived from the virus-free insect vector Nephotettix cincticeps. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified virus showed that among six structural proteins, the P2 outer capsid protein (encoded by genome segment S2) was absent from the TD isolate, whereas all six proteins were present in the transmission-competent (TC) isolate. P2 was not detected on immunoblots of rice plants infected with the TD isolate. Genome segment S2 and its transcript were detected in both TD and TC isolates. Sequence analysis of the S2 segment of the TD isolate revealed the presence of a termination codon due to a point mutation in the open reading frame, which might explain the absence of P2 in the TD isolate. These results demonstrate that the P2 protein is one of the factors essential for infection by the virus of vector cells and, thus, influences transmissibility by vector insects.

Simultaneous injection of round spermatid nuclei from mice and hamster oscillogen can initiate the normal development of mouse embryos.

PURPOSE: In the mouse, mature oocytes that have been injected with spermatid nuclei failed to become activated. Additional stimulation is required to trigger activation of the oocytes that leads to embryo development. This study was performed to determine whether simultaneous injection of mouse round spermatids and hamster oscillogen can fertilize oocytes and contribute to normal embryo development. MATERIALS AND METHODS: We simultaneously injected mouse oocytes with mouse round spermatid nuclei and a preparation of oocyte-activating protein (oscillogen) from hamster spermatozoa and compared the results with those of injection of testicular spermatozoa. RESULTS: The incidence of normal fertilization and embryo development after simultaneous injection of round spermatid nuclei and hamster oscillogen was not significantly different from that after the injection of testicular spermatozoa. Moreover, the rate of development of two-cell embryos to term did not differ very much between the two groups of oocytes. CONCLUSIONS: Simultaneous injection of round spermatid nuclei and oscillogen appears to be an ideal method for successful activation of oocytes by spermatid nuclei in vitro.

Efficacy of enalapril after ineffective theophylline treatment on erythrocytosis after renal transplantation.

Erythrocytosis represents a common complication in renal allograft recipients. Traditional therapies including phlebotomy and bilateral native nephrectomies are cumbersome for both the clinical personnel and the patient. Recently, pharmacological agents such as angiotensin converting enzyme inhibitor and theophylline have been proposed as effective therapies for post-transplant erythrocytosis (PTE). We have treated a PTE patient successfully with enalapril without any side effects and renal dysfunction after theophylline treatment showed no improvement in PTE. A decline in Ht levels was independent of the changes in Epo levels during enalapril treatment. Although the mechanism underlying the beneficial effect of enalapril remains undetermined, enalapril is recommended for the initial treatment of PTE.

Experimental uremia in male rats: effect of interval between partial nephrectomies on testicular function.

Testicular function in stepwise-nephrectomized rats, with a different interval between the two operations, was studied suing male Wistar rats. Serum levels of urea nitrogen and creatinine in stepwise-nephrectomized rats were significantly elevated compared to those in sham-operated rats (p < 0.001). With a 1-day interval between the two operations, these concentrations were considerably higher (p < 0.001) than those in 7-day interval rats. While serum LH levels were significantly reduced (p < 0.001) in 1-day interval rats, FSH levels in this group were considerably higher (p < 0.001) than in other groups. Serum concentrations of androstenedione in 1-day interval rats were significantly suppressed compared to other groups (p < 0.01). Serum testosterone levels in stepwise-nephrectomized rats were considerably lower (p < 0.001) than in sham-operated rats. It is assumed that testicular function in stepwise-nephrectomized rats is influenced by the interval between the two operations.

P2 protein encoded by genome segment S2 of rice dwarf phytoreovirus is essential for virus infection.

Loss of infectivity to insect vector cell monolayers of rice dwarf phytoreovirus (RDV) after CCl4 treatment was associated with the removal of one of the viral proteins from the virus particles. This protein, encoded by genome segment S2 and thus named P2 protein, was located at the outer capsid of the virus particle. When RDV was treated with CCl4 for various times, the reduction in the amount of P2 protein and the loss of viral infectivity to vector cell monolayers were proportional to treatment time. RDV purified using CCl4 treatment thus lacking P2 protein, lost the ability to infect vector insects through feeding and consequently failed to be transmitted to plants. These results suggest that P2 protein is essential for RDV infection of the insect cells and may be related to transmission of the virus by the vector insect.

[Early steroid withdrawal after kidney transplantation].

BACKGROUND: The side effects of steroid are serious problems in renal transplant patients. However, withdrawal of steroid has been controversial. We evaluated the benefits and risk of early steroid withdrawal after renal transplantation. PATIENTS AND METHODS: The outcomes of early steroid withdrawal from triple immunosuppressive drug therapy were analyzed in four living related and one cadaveric renal transplant recipients. The dosage of steroid was gradually reduced and the time of steroid withdrawal after transplantation was 5 to 7.5 months. RESULTS: Four Patients have been able to be free from steroid and maintained stable graft functions and normal urinary findings for 14 to 33 months after withdrawal. The findings of rejection were not observed in the graft specimens obtained by serial biopsies. One patient who received a living related graft developed an increase in serum creatinine level and proteinuria two weeks after discontinuation of steroid. The serum creatinine level returned to that before withdrawal and proteinuria disappeared by steroid readministration. Long term side effects of steroid were not observed in 4 patients with successful steroid withdrawal. CONCLUSION: These results suggest that steroid withdrawal about 6 months after transplantation can be accomplished without jeopardizing graft function in selected renal transplant recipient and the withdrawal in the early stage is preferred for reducing the side effects. Careful and long-term follow up are required to assess the further risk and benefit of steroid withdrawal on immunosuppressive morbidity.

Genetic analysis of Drosophila virilis sex pheromone: genetic mapping of the locus producing Z-(11)-pentacosene.

Z-(11)-pentacosene, Drosophila virilis sex pheromone, is predominant among the female cuticular hydrocarbons and can elicit male courtship behaviours. To evaluate the genetic basis of its production, interspecific crosses between D. novamexicana and genetically marked D. virilis were made and hydrocarbon profiles of their backcross progeny were analysed. The production of Z-(11)-pentacosene was autosomally controlled and was recessive. Of the six D. virilis chromosomes only the second and the third chromosomes showed significant contributions to sex pheromone production, and acted additively. Analysis of recombinant females indicated that the locus on the second chromosome mapped to the proximity of position 2-218.

Norepinephrine contents of human prostatic hyperplasia: differences between pathological subtypes.

Tissue norepinephrine content in benign prostatic hyperplasia (BPH) was evaluated to detect possible histological differences in BPH subtypes and to investigate the correlation between norepinephrine levels and age, prostatic weight and clinical symptom score, respectively. Specimens were obtained from 28 patients who underwent transurethral resection of the prostate. Pathologically, 18 out of 28 specimens were classified as fibromyoadenomatous hyperplasia and the remaining 10 as fibromuscular type. Norepinephrine content in the fibromyoadenomatous type was 133.1 +/- 23.1 ng/g, whereas it was 340.3 +/- 60.5 ng/g in the fibromuscular type. Norepinephrine level in the former group was significantly lower than that in the latter group (p < 0.001). In both groups, there was no correlation between norepinephrine content, age and clinical symptom score, while the norepinephrine content had a reverse correlation with prostatic weight only in the former group (p < 0.05). In conclusion, norepinephrine levels were dependent upon histological differences, especially upon the amount of smooth muscle elements, in the evaluated specimen. Severity of prostatism and patients' age showed no correlation with tissue norepinephrine content.

Reproductive isolation between Drosophila lini and its siblings.

Courtship behavior and reproductive isolation between nine strains of Drosophila lini and its siblings from Taiwan (TWN), Dinghushan (DHS) and Nankunshan (NKS) in China, and Pyinoolwin (MMY) and Yangon (RGN) in Myanmar were investigated. No premating and postmating isolation between the Taiwan and mainland China strains were found. Crosses between mainland China (DHS and NKS) or the TWN strain and the MMY or RGN strain produced fertile F1 hybrid females and sterile F1 hybrid males. Crosses between MMY strains and RGN strains which showed strong premating isolation produced either no F1 hybrids, or fertile F1 hybrid females and sterile males in some cases. These results suggest the existence of at least three genetically distinct sibling species of D. lini.

Hormone profiles and testicular histology in azoospermic men with Y-autosome translocation and autosomal translocation.

Hormone profiles and testicular histology were studied in azoospermic men with Y-autosome translocation and autosomal translocation. Plasma levels of LH, FSH, prolactin, and testosterone were within normal ranges in these anomalies. The responses of plasma gonadotropins to LH-RH and plasma testosterone to hCG were similar in the two groups. Johnsen score count, diameter of the seminiferous tubules, wall thickness, and Leydig cells per seminiferous tubules were similar in the two groups. It would appear that hormone conditions an alterations are similar in azoospermic men with Y-autosome translocation and autosomal translocation.

P element-induced mutations in Drosophila melanogaster showing high interspecific crossability between D. melanogaster females and D. simulans males.

Homozygous stocks for the second or the third chromosome of Drosophila melanogaster with a single insertional plwB element were screened for high crossability with D. simulans. Reciprocal crosses between each of these stocks and D. simulans were made, and the insemination rate at two or three days was examined. From two cycles of screening of the original 575 stocks, one stock (# 687) which showed high insemination rate was selected and was backcrossed to a w strain to substitute the background. We obtained a stock which showed 10% insemination rate with D. simulans males (control was 0%). No stocks exhibiting a high crossability with D. simulans females were acquired. Revertant strains, from which the P element had been lost, were obtained from the backcrossed # 687 stock. The insemination rates of 13 revertants to D. simulans males ranged from 1% to 33%. Seven of these 13 were not significantly different from the control line but were significantly different from the backcrossed # 687 stock. It was concluded that the mutation showing high crossability with D. simulans males was caused by the P element transposition.

Epistatic interactions among the P element-induced high interspecific crossability strains in Drosophila melanogaster.

Five Drosophila melanogaster strains showing high interspecific crossability with D. simulans males, derived from the previous screening of a set of autosomal plwB transposants, were selected and the effect of the plwB insertion under the same genetic background (white strain) on the interspecific crossability was examined. This phenotype was recessive in the two strains but semidominant in the other three strains. Trans-heterozygotes, however, showed high interspecific crossability compared with the parental homozygotes, suggesting some epistatic interactions between them. In three strains, the effect of the plwB insertion region in different backgrounds (w1118 strain) on the crossability was also tested. Homozygotes of a strain (#687) showed high interspecific crossability comparable to the w background, while homozygotes of both #68 and #783 strains showed lower crossability than w1118. Although #783 heterozygotes showed intermediate values between #783 homozygotes and w1118, #68 heterozygotes showed a significantly higher insemination rate than w1118 and the #68 homozygotes. These results suggest that the region around the plwB insertion sites of #68 and #783 affects the interspecific crossability either positively or negatively depending on the genetic background. In all the stocks, positive correlation between interspecific crossability and the intraspecific mating speed was detected.