Genetische Untersuchungen bei funktionell-obstruktiver subvalvulärer Aortenstenose (irregulär hypertrophischer Kardiomyopathie)

Summary Family investigations have been carried out on 32 propositi with functional obstructive subvalvular aortic stenosis. In the families of 15 propositors members were further-more affected. According to our own observations as well as to the literature this heart disease shows an autosomal dominant mode of inheritance with a reduced penetrance and variable manifestations. Using the maximum-likelihood-method, the risk of the brothers or sisters to be affected is calculated as being between (k=0, r_min=1) and (k=1, r_min=1). The probability of parents in the “familial” observations to be affected is between 32.9±8.1 and 33.3±8.1. Only one half of the cases observed are “familial”, the others are “sporadic”. It is not impossible, that a part of the sporadic cases could be dominant mutants, because the mean age of the fathers at the birth is higher than expected.

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Direktor: Prof. Dr. med. P. E. Becker

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Genetische Untersuchungen bei angeborener organischer subvalvulärer Aortenstenose

Zusammenfassung Ausgehend von 45 Probanden mit angeborenen organischen subvalvulären Aortenstenosen wurden Familienuntersuchungen durchgeführt. 29 Probanden hatten eine einfache (isolierte) Subaortenstenose (Tabelle 1), 16 weitere einen mit zusätzlichen Herzdefekten wie angeborener valvulärer Aortenstenose (n=3), Ductus arteriosus persistens (n=7), Aortenisthmusstenose (n=5) und Ventrikelseptumdefekt (n=2) kombinierten Typ (Tabelle 2 u. 3).Die Häufigkeit der angeborenen organischen Subaortenstenose liegt wahrscheinlich zwischen 0,0065% und 0,0162%.Das Geschlechtsverhältnis beträgt bei Zusammenfassung der eigenen Fälle mit Literaturbeobachtungen 2 :1 (Tabelle 3 u. 4).In den Familien der 45 Probanden wurden alle lebenden Eltern, Geschwister sowie Kinder, z. T. auch Großeltern und weitere Verwandte untersucht. In 11 Fällen famden sich in den Sippen weitere Angehörige mit angeborenen Herzfehlern (Tabelle 1 u. 2). In der Geschwisterschaft von Kranken beträgt die nach dem Maximum-likelihood-Verfahren errechnete Erkrankungswahrscheinlichkeit p=0,0361±0,00205 (k=0,^rmin=1). Die Erkrankungswahrscheinlichkeit der Eltern, errechnet nach der Weinbergschen Probandenmethode, beträgt 3,3±1,9% (Tabelle 6).Ein Proband hat einen eineiigen, nicht betroffenen Zwillingsbruder.Das Durchschnittsalter der Väter der Probanden beträgt 30,6 Jahre, das der Mütter 28,6 Jahre und entspricht dem der Kontrollgruppe (Tabelle 7).Die Prüfung der Geburtenordnung nach dem Haldane-Smith-Verfahren ergab keine signifikante Differenz zwischen Beobachtung und Erwartung (Tabelle 8).Genetisch liegt den angeborenen organischen Subaortenstenosen vermutlich ein multifaktorielles genetisches System mit additiver Polygenie und Schwellenwerteffekt zugrunde.

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Genetic investigations in congential organic subvalvular aortic stenosis

Summary Genetic investigations have been carried out on 45 propositi with congenital organic subvalvular aortic stenosis. From these, 29 had an isolated subvalvular aortic stenosis (see Table 1), 16 a type combined with other cardiac defects as valvular aortic stenosis (n=3), patent ductus arteriosus (n=7), coarctation of the aorta (n=5), and ventricular septal defect (n=2) (see Table 2 and 3).The incidence of this heart defect among all live births is probably 0.0065%–0.0162%.According to our own observations as well as to the literature the sex ratio of patients with organic subvalvular aortic stenosis is 2 :1 (see Table 3).In the families of the 45 propositi were examined all living parents, siblings and infants, in some cases also grand-parents and other family members. In all of them 11 relatives were affected with similar or-rarely-dissimilar congenital heart diseases (see Table 1 and 2). Using the maximum-likelihood-method, the risk of siblings to be affected is calculated as beeing p (k=0,^rmin=1). Using the Weinberg method the probability of parents to be affected is 3.3±1,9% (see Table 6).One index patient had a monozygotic co-twin who is not affected.The average age of the fathers is 30.6 years and of the mothers 28.6 years (see Table 7). There is no statistical difference between parental age and that of the control sample.The birth-order effect was examined in our 45 patients (see Table 8) by the Haldane-Smith-method. There is no difference between observation and expectation.The hypothesis of a multifactorial genetic background is supposed as mode of inheritance of congenital organic subvalvular aortic stenosis.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.     

The effect of interspecific mating on sex ratios in the twospotted spider mite and the Banks grass mite (Acarina: Tetranychidae)

Mixed populations of the twospotted spider mite (TSM),Tetranychus urticae (Koch), and the Banks grass mite (BGM),Oligonychus pratensis (Banks), occur on corn and sorghum plants in late summer in the Great Plains. Interspecific matings between these arrhenotokous species occur readily in the laboratory but yield no female offspring. The effect of interspecific mating on female: male sex ratios was measured by examining the F₁ progeny of females that mated with both heterospecific and conspecific males in no-choice situations. TSM females that mated first with BGM males and then with TSM males produced a smaller percentage of female offspring than TSM females that mated only with TSM males (43.1±5.8 and 78.9±2.8% females, respectively). Similarly, BGM females mated with heterospecific males and then with conspecific males produced fewer female offspring than females mated only with BGM males (55.7±5.2 and 77.5±2.5%, respectively). Lower female: male sex ratios were produced also by BGM females that mated with TSM males after first mating with conspecifics (62.4±3.4%). In mixed populations containing males of both species, females also produced lower female: male sex ratios, but these ratios were not as low as expected based on mating propensities and progeny sex ratios observed in no-choice tests. These data suggest that interspecific mating may substantially reduce female fitness in both mite species by reducing the output of female offspring, but in mixed populations this effect is mitigated by unidentified behavioral mechanisms.     

Mating Aggregations and Mating Success in the Flower Thrips, Frankliniella schultzei (Thysanoptera: Thripidae), and a Possible Role for Pheromones

Aggregations of Frankliniella schultzei males were observed on the corollas of Hibiscus rosasinensis and Gossypium hirsutum flowers in southeast Queensland. Aggregations were seen only on the upper surfaces of corollas but may have occurred on other flower parts, which were hidden from view. Conspecific females entered aggregations and a small proportion of them mated [18% (n = 163), H. rosasinensis; 30% (n = 181), G. hirsutum]. Most females (87 and 72%, respectively) that did not mate in aggregations walked to other flower parts. Behavior was difficult to observe on these parts, but mating was sometimes observed there. The number of females that landed within aggregations on the upper surfaces of both H. rosasinensis and G. hirsutum corollas was highly correlated with the number of males (r = 0.88, r = 0.93, respectively; P < 0.001). Significantly more mating pairs were observed in high-density aggregations (mean ± SE, 1.10 ± 0.22 and 4.44 ± 0.48, respectively) than in low-density aggregations (0.37 ± 0.11 and 1.67 ± 0.29, respectively) (P < 0.05) on flowers of both species. More F. schultzei females were attracted to sticky traps baited with live conspecific males set among flowering Ipomoea indica (mean ± SE, 8.83 ± 0.32) and G. hirsutum (10.90 ± 0.79) plants than to control traps (0.10 ± 0.05 and 0.70 ± 0.25, respectively) (P < 0.05), presumably in response to male-produced pheromones. Significantly more females were attracted to traps with high male densities than to traps with low densities. We found no statistical evidence that aggregation size influenced mating success (proportion males that mated). Mating success, however, should be evaluated with respect to mating on all flower parts and not just the upper surfaces of corollas. The results of this study constitute the first behavioral evidence for an attractant sex pheromone in thrips.     

The adaptive significance of mate guarding in the soapberry bug,Jadera Haematoloma (Hemiptera: Rhopalidae)

Male soapberry bugs (Jadera haematoloma)face severe mating competition at the northern edge of their range due to male-biased adult sex ratios. Copulations lasting up to 11 days may serve a mate guarding function (encompassing four or more ovipositions), but copulation duration is highly variable, with some pairings lasting as little as 10 min. Data were gathered to describe factors that influence the reproductive costs and benefits of prolonged copulation. Estimated copulation durations (mean ± SD) were 20 ± 23 h in the lab and 50 ± 8 h in the field and were only weakly affected by sex ratio. Females mated for 5 min produced as many fertile eggs as those mated for 600 min laid; they became depleted of fertile sperm after about 25 days. In twicemated females, the first male's paternity was reduced by about 60%, and all females (N = 13) whose mates were removed experimentally mated again within an average of 6 min. The outcome of sperm competition on a perclutch basis was not highly predictable. The possibility of increased sperm displacement in longer copulations was not tested. Males often guarded females during oviposition and successfully defended them from intruding single males by recopulating. Such intrusions occurred in the majority of oviposition attempts observed in nature. Even though most females mated promiscuously, in a focal aggregation with a mean sex ratio of 2.2 ± 0.4 males/female, the interval between matings by males was commonly several days. Males appeared to respond facultatively to several aspects of the distribution and availability of females. The intensities of mating competition and sperm competition indicate that monogamous mate guarding should be favored over nonguarding in nature. Unpredicted brief. pairings may result from assessment by males of female reproductive value or of their own physical condition, or from female resistance.     

Female-biased Sex Ratios in the Neotropical Treehopper Umbonia ataliba (Homoptera: Membracidae)

The authors report and explain female-biased sex ratios in the neotropical treehopper Umbonia ataliba Homoptera: Membracidae at Monteverde, Costa Rica. Umbonia ataliba mothers semelparously oviposit egg masses into host-plant branches, make feeding holes, and guard the eggs and the nymphs until the young moult to become adults. At adulthood, offspring sex ratios are female-biased, with families having, on average, one male per 3.17 females (SD = 0.149, n = 48). The female bias does not appear to be explained by the hypothesis that males are more difficult to raise to independence: males are smaller than females, males have a shorter development time, males do not require disproportionately more feeding holes, and males do not experience higher mortality in families that are unprotected from parasites and predators, rather, females die more often in protected families. Thus females, not males, may be more difficult to raise to independence. The authors investigated whether increases in the size of males and females increased the fitness of either sex disproportionately, but found no relationship between size and fitness for either sex. We found evidence that local-mate competition conditions and inbreeding occur. Mating occurs at the natal site and nearly all copulations take place between siblings (99.3 %, n = 153 copulations). Most females (mean proportion of females = 0.65, SD = 0.33, n = 7 families) copulate with their male siblings prior to dispersing; whether the unmated proportion copulates later is unknown. This paper suggests that the numerical bias reflects an investment bias favoured under selection by inbreeding and local-mate competition conditions.     

Voltage-activated current properties of male and female mouse vomeronasal sensory neurons: sexually dichotomous?

The vomeronasal organ, the chemosensory organ of the vomeronasal system, is vital in determining sexual and gender-specific behavior in mice. Here, whole-cell voltage-activated currents of individual mouse vomeronasal sensory neurons of two strains (BALB/c and CBA) were measured and correlated to sex in each strain. The average resting membrane potentials, maximal outward current magnitudes, and kinetics of activation and inactivation, were found to be independent of sex. Maximal inward current magnitudes differed significantly across gender in CBA, whereas they did not significantly differ in male and female BALB/c mice: BALB/c males –347±45 pA (n=51), and females –430±56 pA (n=27); CBA males –308±36 pA (n=56) and females –155±18 pA (n=28). These results suggest that some voltage-activated properties may differ slightly according to gender and to strain.D.M. Dean and A. Mazzatenta contributed equally to this work     

Seasonal changes in the population of the mite Unionicola intermedia (Hydrachnellae,Acari) from the freshwater mussel Anodonta anatina (Unionidae)

Although numbers were low in winter, males of Unionicola intermedia were found throughout the year. A mean of 2.5 (±0.26 SE) males per mussel was found with a range of 0 to 20. Females had a mean of 13.07 (±0.87 SE) per mussel and a range from 0 to 57, with the highest mean in August. The incidence of males was much lower than that of females. Nymphs and females were highly aggregated and males showed aggregation at a lower level of significance for nine months of the year. Although the primary sex ratio is unknown, the tertiary sex ratio is 86% female and on a monthly basis ranged from 68.9% to 96.7% female. It is speculated that reproduction is arrhenotokous. The sex ratio and the significant seasonal variations of the active stages may be influenced by the dispersal pattern of this species and by the biology of its host.     

Biochemical and physiological characteristics of semen of sex-reversed female rainbow trout (Oncorhynchus mykiss, Walbaum)

This works studies the biochemical (protein concentration, osmolality, antitrypsin activity, lactate dehydrogenase activity) and physiological characteristics (sperm motility characteristics) of semen of sex-reversed female rainbow trout (n = 42) obtained with the application of 11β-hydroksyandrostendione for sex reversal. All data were arbitrarily divided into three classes depending on the percentage of sperm motility: I XX < 25%; II XX 25-50% and III XX > 50%. The average percentage of sperm motility was 18 ± 7% n = 12 (group I XX); 42 ± 6% n = 15 (group II XX) and 65 ± 12% n = 15 for group III XX, respectively) to link the values of semen parameters to the maturation stage of semen. Semen from 12 normal males of the same age was used as a reference group. Sperm concentration as well as protein concentration, osmolality, antitrypsin activity, and lactate dehydrogenase activity in seminal plasma of sex-reversed females were higher compared with the values obtained for normal male rainbow trout. The values of these parameters declined with the increasing percentage of sperm motility toward values established for normal males. The fertilization success of semen (3 × 10⁶ spermatozoa/egg) of sex-reversed females was very high (above 90%) for both the percentage of eyed embryos and hatched larvae and was related to sperm motility classes. Correlations between the quality parameters of sex-reversed females semen corresponded to those established previously for the semen of normal male rainbow trout. Antitrypsin activity, lactate dehydrogenase, protein concentration, and osmolality were found to be characteristic of seminal plasma of sex-reversed females. The maturity of sex-reversed female spermatozoa seems to be associated with the decline in the values of those parameters toward the values characteristic for seminal plasma of normal males.     

Interactions between anion exchange and other membrane proteins in rabbit kidney medullary collecting duct cells

Summary In separated outer medullary collecting duct (MCD) cells, the time course of binding of the fluorescent stilbene anion exchange inhibitor, DBDS (4,4-dibenzamido-2,2-stilbene disulfonate), to the MCD cell analog of band 3, the red blood cell (rbc) anion exchange protein, can be measured by the stopped-flow method and the reaction time constant, _DBDS, can be used to report on the conformational state of the band 3 analog. In order to validate the method we have now shown that the ID_50,DBDS,MCD (0.5±0.1 m) for the H₂-DIDS (4,4-diisothiocyano-2,2-dihydrostilbene disulfonate) inhibition of _DBDS is in agreement with the ID_50,Cl ^–,_MCD (0.94±0.07 m) for H₂-DIDS inhibition of MCD cell Cl^– flux, thus relating _DBDS directly to anion exchange. The specific cardiac glycoside cation transport inhibitor, ouabain, not only modulates DBDS binding kinetics, but also increases the time constant for Cl^– exchange by a factor of two, from _Cl=0.30±0.02 sec to 0.56±0.06 sec (30mm NaHCO₃). The ID_50,DBDS,MCD for the ouabain effect on DBDS binding kinetics is 0.003±0.001 m, so that binding is about an order of magnitude tighter than that for inhibition of rbc K⁺ flux (K _I,K ⁺,_rbc=0.017 m). These experiments indicate that the Na⁺,K^–-ATPase, required to maintain cation gradients across the MCD cell membrane, is close enough to the band 3 analog that conformational information can be exchanged. Cytochalasin E (CE), which binds to the spectrin/actin complex in rbc and other cells, modulates DBDS binding kinetics with a physiological ID_50,DBDS,MCD (0.076±0.005 m); 2 m CE also more than doubles the Cl^– exchange time constant from 0.20±0.04 sec to 0.50±0.08 sec (30mm NaHCO₃). These experiments indicate that conformational information can also be exchanged between the MCD cell band 3 analog and the MCD cell cytoskeleton.     

The “Reading the Mind in the Eyes” Test: Complete Absence of Typical Sex Difference in ~400 Men and Women with Autism

The “Reading the Mind in the Eyes” test (Eyes test) is an advanced test of theory of mind. Typical sex difference has been reported (i.e., female advantage). Individuals with autism show more difficulty than do typically developing individuals, yet it remains unclear how this is modulated by sex, as females with autism have been under-represented. Here in a large, non-male-biased sample we test for the effects of sex, diagnosis, and their interaction. The Eyes test (revised version) was administered online to 395 adults with autism (178 males, 217 females) and 320 control adults (152 males, 168 females). Two-way ANOVA showed a significant sex-by-diagnosis interaction in total correct score (F(1,711) = 5.090, p = 0.024, η_p ² = 0.007) arising from a significant sex difference between control males and females (p < 0.001, Cohen’s d = 0.47), and an absence of a sex difference between males and females with autism (p = 0.907, d = 0.01); significant case-control differences were observed across sexes, with effect sizes of d = 0.35 in males and d = 0.69 in females. Group-difference patterns fit with the extreme-male-brain (EMB) theory predictions. Eyes test-Empathy Quotient and Eyes test-Autism Spectrum Quotient correlations were significant only in females with autism (r = 0.35, r = -0.32, respectively), but not in the other 3 groups. Support vector machine (SVM) classification based on response pattern across all 36 items classified autism diagnosis with a relatively higher accuracy for females (72.2%) than males (65.8%). Nevertheless, an SVM model trained within one sex generalized equally well when applied to the other sex. Performance on the Eyes test is a sex-independent phenotypic characteristic of adults with autism, reflecting sex-common social difficulties, and provides support for the EMB theory predictions for both males and females. Performance of females with autism differed from same-sex controls more than did that of males with autism. Females with autism also showed stronger coherence between self-reported dispositional traits and Eyes test performance than all other groups.     

Genetic variation, genetic structure and effective population size in the tropical holoparasitic endophyteBdallophyton bambusarum (Rafflesiaceae)

The genetic population structure inBdallophyton bambusarum, an endoparasite, was studied in ten subpopulations from a subdeciduous tropical forest in Veracruz Mexico. The sample was analyzed using seven polymorphic loci in cellulose acetate electrophoresis. Isozyme data indicated that the subpopulations ofB. bambusarum contained high genetic variability (H_ep = 0.452 ± 0.045, S.E.). Our analysis suggests that almost each inflorescence ofB. bambusarum is an individual. The subpopulations studied were genetically similar (average Nei's genetic identity 0.941 ± 0.051 and F _st values 0.097 ± 0.026), suggesting that genetic differentiation among subpopulations was small. Direct estimates of effective population size was derived from observations of three fluorescent dyes, and from the genetic neighborhood area derived from these data. The neighborhood area, multiplied by the total density of individuals, gave an N_e = 124.84 plants, and when corrected to consider the proportion of males and females gave an N_e = 118.59 individuals. An indirect estimate of Nm was obtained from the F _st values (mean Nm=2.037), giving an indirect estimate of the effective population size N_b = 12.8 individuals. Both values are relatively high when compared to other plant studies. The gene flow and/or effective populations size of the studied subpopulations ofB. bambusarum are believed to be large enough to prevent differentiation among subpopulations due to genetic drift.     

Oviposition schedules,survivorship curves,and mortality factors within trees of two cerambycid beetles (Coleoptera: Cerambycidae), the Japanese pine sawyer,Monochamus alternatus hope,and sugi bark borer,Semanotus japonicus lacordaire

Summary Oviposition schedules under laboratory conditions, survivorship curves, and mortality factors within trees of two cerambycid beetles, Japanese pine sawyer (JPS),Monochamus alternatus Hope, and sugi bark borer (SBB),Semanotus japonicus Lacordaire, were investigated. Average longevities of reared adults of JPS were 38.1 days for males and 42.3 days for females; those of SBB were 15.7 days for males and 23.8 days for females. It was confirmed that the JPS must feed on the pine branches for full maturation after emergence, but SBB need not; they are able to lay eggs soon after emergence. The average fecundities of JPS and SBB were 32.9 and 90.5, respectively. Thus, the JPS lay fewer eggs for a long time with continuous maturation feeding, whereas the SBB lay more eggs for short time without maturation feeding. Average survivorship curves of JPS within dead pine trees in 8 pine forests were theDeevey's B type, showing a constant mortality through the pre-imaginal stages in the trees. On the other hand those of SBB in 4 cedar stands approached theDeevey's type, suggesting that the high mortality occurred at an early stage in the trees. Average mortalities of JPS between the appearance of oviposition scars and adult emergence in 8 forests ranged from 62.3% to 95.2%. Intraspecific ompetition of JPS resulting from overcrowding in dead pine trees appeared to be main mortality factor. For SBB, as most larvae were killed by resin flow in living trees, this appeared to be the main mortality factor for this species.     

Gender variation inSilene acaulis (Caryophyllaceae)

Silene acaulis (Caryophyllaceae) is an alpine-arctic plant with a gynodioecious breeding system, but significant variation in sex expression has been reported. In addition, population sex ratio may be modified by the anther-smutMicrobotryum violaceum (Pers.)Deml & Oberwinkler, which sterilizes individuals of both sexes. A survey was undertaken at several sites on Baffin Island, Canada, to determine sex ratio and assess variation in female function among morphologically hermaphroditic individuals. The degree of anthersmut infection was also measured. Six sites had high female frequencies ranging from 72–80% and < 2% smut infection. High female frequencies may indicate cytoplasmic control of male-sterility. A seventh site from a mesic habitat had only 50% females and a higher rate of smut infection (22%). Of the three sites studied in detail, 84% of females set at least one capsule compared to only 25% of the hermaphrodites, indicating reduced female function. Hermaphrodites displayed significant variability in female function. Flowers with short styles (< 4.0mm) had degenerated ovules, and field estimates confirmed that only 5% of these individuals set capsules, but comprised the majority (> 55%) of hermaphrodites. Although hermaphrodites with short-styled flowers functioned solely as males, there was no increase in pollen production compared to long-styled hermaphrodites. Long-styled hermaphrodites produced the same number of ovules as females, and all set at least one capsule but these plants were uncommon (< 11%) at all sites.     

Sex Differences in Olfactory Communication in Saguinus labiatus

We assessed behaviors involved with depositing and receiving scent in three captive heterosexual pairs of red-bellied tamarins (Saguinus labiatus). The frequencies of scent deposition and scent investigatory behaviors differed between the sexes. Females scent marked exclusively by the anogenital gland. Males deposited 95.8% of scent marks via the anogenital gland and 4.2% via the sternal gland. Females scent marked at a significantly higher rate than that of males (0.9 ± 0.1 versus 0.3 ± 0.1 per 20 min, respectively). Males investigated the scent of their opposite-sex partners whereas females investigated no male scent. Mean ± SEM latency for males to investigate female scent was 208.7 ± 65.0 sec. Around 9% of all scent marks were overmarked within 8 min and there was a nonsignificant trend for males to overmark the scent of their female partners than vice versa. We discuss the sex differences in olfactory communication in red-bellied tamarins in terms of sexual selection theory.     

Structural characteristics of the saxitoxin receptor on nerve

Summary The effects of uranyl ion (UO ₂ ²⁺ ; at low concentrations binds specifically to phosphate groups) and the cationic dye methylene blue (MB⁺; binds strongly to carboxyl groups) on saxitoxin (STX) potency in crayfish axon has been studied by means of intracellular microelectrodes. At pH 6.00±0.05 and 13.5mm Ca²⁺, addition of 10.0 m UO ₂ ²⁺ +5.0nm STX had only slightly, if any, less effect on the spike's maximum rate of rise [0.79±0.04 (viz., mean±sem) of control value] than did addition of 5.0nm STX alone (0.72±0.05). Under the same conditions of pH and Ca²⁺ concentration, 1.0mm MB⁺ had approximately the same effect: 1.0mm MB⁺+5.0nm STX, 0.76±0.03; 5.0nm STX alone, 0.70±0.04. However, at pH 7.00±0.05 and lower Ca²⁺ concentrations, 1.0mm MB⁺ significantly reduced STX potency. Using 6.0mm Ca²⁺: 1.0mm MB⁺+5.0nm STX, 0.92±0.01; 5.0nm STX alone, 0.68±0.08. Using 3.0mm Ca²⁺, the corresponding values were 0.94±0.03 and 0.67±0.04. It is concluded that: (1) In accord with previous suggestions, the ionized acidic group known to exist in the Na channel (and to which a guanidinium group of STX appears to bind) is very likely a carboxyl group and not a phosphate group. (2) The accessible part of the Na channel mouth serving as the saxitoxin receptor probably does not include phospholipid in its structure proper.     

Onion fly,Delia antiqua,oviposition and mating as influenced by insect age and dosage of male reproductive tract extract (Diptera: Anthomyiidae)

One hundred percent of virgin female onion flies,Delia antiqua, receiving 1/20 of a male equivalent of an aqueous extract of mature male reproductive tract remained unmated in the presence of males and began laying unfertilized eggs at a normally mated rate of about 20 eggs/female/day. The 50% behavioral response (BR₅₀) fell between 1/40 and 1/20 of a male equivalent. Sex peptide responses are not always all-or-none. Some females receiving extract at 1/40 male equivalent oviposited at an intermediate rate. Moreover, at low sex peptide dosages, some females were fully activated ovipositionally but were receiptive to mating. A low level of sex peptide was present in 1-day-old males. Sex peptide titer rose with age until plateauing by 6 days posteclosion. Males began mating at 3 days, when they first had ample mature sperm; 50% of 6-day-old males mated. The mean number of females inseminated per male exposed to an excess of virgin females over 24 h was 4.3±0.6 (±SE). Presence of mature eggs was not always a prerequisite for mating, although probability of insemination was correlated with egg maturation. One-day-old preovipositional females receiving 1/20 of a male equivalent of extract began ovipositing when they had mature eggs at 5–6 days old. Therefore, sex peptide may act early and permanently or have a long half-life and affect behaviors once females reach sexual maturity. Male flies provide females with an excess of sex peptide in many cases.D. antiqua males transferred ca. 5–10 times more sex peptide than necessary to activate females fully. We suggest this excess is related to the speed of female response. It is yet unclear whether sex peptide potency or titer in Diptera has become exaggerated by intra- or intersexual selection.     

Amino acid transport system y+L of human erythrocytes: Specificity and cation dependence of the translocation step

The transport specificity of system y⁺L of human erythrocytes was investigated and the carrier was found to accept a wide range of amino acids as substrates. Relative rates of entry for various amino acids were estimated from their trans-effects on the unidirectional efflux of l-[¹⁴C]-lysine. Some neutral amino acids, l-lysine and l-glutamic acid induced marked trans-acceleration of labeled lysine efflux; saturating concentrations of external l-leucine and l-lysine increased the rate by 5.3±0.63 and 6.2±0.54, respectively. The rate of translocation of the carrier-substrate complex is less dependent on the structure of the amino acid than binding. Translocation is slower for the bulkier analogues (l-tryptophan, l-phenylalanine); smaller amino acids, although weakly bound, are rapidly transported (l-alanine, l-serine). Half-saturation constants (±sem) calculated from this effect (l-lysine, 10.32±0.49 m and l-leucine, 11.50±0.50 m) agreed with those previously measured in cis-inhibition experiments. The degree of trans-acceleration caused by neutral amino acids did not differ significantly in Na⁺, Li⁺ or K⁺ medium, whereas the affinity for neutral amino acids was dramatically decreased if Na⁺ or Li⁺ were replaced by K⁺. The observation that specificity is principally expressed in substrate binding indicates that the carrier reorientation step is largely independent of the forces of interaction between the carrier and the transport site.We wish to thank Dr C.A.R. Boyd for helpful discussions and Prof. H.N. Christensen for sharing with us very relevant bibliographic material. We are grateful to FONDECYT (1282/91) and DTI (B 2674) (Chile) for financial assistance.     

Thermal acclimation in the grain miteAcarus siro (Acari: Acaridae)

Grain mites reared on wheat germ at 21±1°C and 85% r.h. were treated (acclimated) as adults at 0, 14, 28 or 33°C for 1 or 4 days. Fecundity, longevity and numbers of F₁ females and males produced were compared. A treatment of 1 day was enough to acclimateAcarus siro and change the studied developmental parameters. Acclimation always lowered fecundity but the magnitude of the effect was dependent upon the temperature regime. The number of males and females emerging differed greatly among various temperature regimes; however, the sex ratio of emerged adults remained in most instances quite constant.