Consequences of elevating plasma testosterone in females of a socially monogamous songbird: evidence of constraints on male evolution?

To explore whether selection for testosterone-mediated traits in males might be constrained by costs of higher testosterone to females, we examined the effects of experimental elevation of plasma testosterone on physiological, reproductive, and behavioral parameters in a female songbird, the dark-eyed junco (Junco hyemalis). We used subcutaneous implants to elevate testosterone (T) in captive and free-living female juncos. In captive birds, we measured the effects of high T on body mass, feather molt, and brood patch formation. In the field, we monitored its effects on the timing of egg laying, clutch size, egg size, egg steroid levels, incubation, and nest-defense behavior. Females implanted with testosterone (T-females) had significantly higher circulating levels of testosterone than did control females (C-females). Captive T-females had lower body mass, were less likely to develop brood patches, and delayed feather molt relative to C-females. Among free-living females, the interval between nest completion and appearance of the first egg was longer for T-females than for C-females and egg yolk concentrations of testosterone were higher, but there were no significant differences in estradiol levels, clutch size, or egg size. Incubation and nest defense behavior were also similar between T- and C-females. Our results suggest that selection on males for higher testosterone might initially lead to a correlated response in females producing changes in body mass and feather molt, both of which could be detrimental. Other possible female responses would be delayed onset of reproduction, which might reduce reproductive success, and higher yolk testosterone, which might have either positive or negative effects on offspring development. We found no reason to expect reduced parental behavior by females as a negative fitness consequence of selection for higher testosterone in males.     

Sex differences in the control of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Interaction of estrogen, testosterone and insulin in the regulation of enzyme levels in vivo and in cultured hepatocytes

Control of the activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and malate dehydrogenase was investigated in intact rats and in hepatocyte cultures. 1) Adult females had 2-fold greater activities of hepatic glucose-6-phosphate- and 6-phosphogluconate dehydrogenases than adult males, but similar activities of malate dehydrogenase. Castrated males showed decreased activities of all three enzymes in comparison to age- and weight-matched intact controls. In starved animals the activities of all three enzymes decreased significantly. After refeeding with nonpurified diet the activities returned to the prestarved levels in females, but increased to clearly higher values in intact and castrated males. 2) Estrogen levels were in the same range in immature and adult male and female rats. Testosterone levels were highest in adult males, clearly lower in adult females (1/8) and immature males (1/8), still lower in immature females (1/15) and lowest in castrated males (1/40). A simple correlation of the sex differences in these hormone levels to sex differences in glucose-6-phosphate- and 6-phosphogluconate dehydrogenase activities was not apparent. 3) In serum-free, dexamethasone-supplemented 48-h cultures of hepatocytes from both male and female rats the basal activities of glucose-6-phosphate dehydrogenase were the same; they were increased 2-3 fold by insulin alone, 1.5 fold by estrogen alone and 4-5 fold by insulin plus estrogen. Apparently sex differences did not persist in 48-h cell cultures. 4) In 48-h cultures of male hepatocytes, then used as the experimental model, insulin alone increased the activity not only of glucose-6-phosphate dehydrogenase but also of 6-phosphogluconate and malate dehydrogenases.(ABSTRACT TRUNCATED AT 250 WORDS)     

Uptake of the yolk protein, lipovitellin, by developing crustacean oocytes

A variety of cytochemical techniques were used to demonstrate how crustacean lipovitellin accumulates within the egg. It was found that a protein serologically identical to the lipovitellin of yolk spheres was present in the hemolymph of vitellogenic crustaceans, but was absent from the hemolymph of males and immature females.In the three crustacean species studied (Uca pugilator, Cambarus clarkii, and Libinia emarginata), pinocytosis of fluorescein-conjugated lipovitellin and trypan blue occurred only during those periods when oocytes were accumulating yolk.It may be concluded from the present studies that yolk spheres develop in crustacean eggs primarily through micropinocytotic uptake of lipovitellin from the hemolymph, although other oocyte proteins appear to be made in the oocyte.     

Vitellogenesis in Anolis pulchellus: induction of VTG-like protein in liver explants from male and immature lizards.

Vitellogenin (VTG) synthesis has been described as an ideal system to study the hormonal regulation of gene expression. In Xenopus the molecular aspects of this control have been analyzed; however, in other non-mammalian species such as reptiles, very few studies approaching this level have been undertaken. We report on the induction by estradiol-17 beta of VTG-like proteins in liver explants from adult males and immature male and female lizards (A. pulchellus). A concentration of 10(-7) M was optimum for adult males while a higher concentration (10(-6) M) is required for the immature animals. No differences were observed in the hormonal induction in male and female immature animals, suggesting that there are no sexual distinctions in the liver at this stage. The effect of the hormone in male liver appears to be primarily on mRNA synthesis, since increases in 3H-uridine incorporation in total RNA were prevented by addition of 1 microgram/ml of the RNA polymerase II inhibitor alpha-Amanitin; however, rRNA synthesis was also increased as observed by agarose gel analysis. A 48 hr lag period was required for the detection of the intracellular as well as the secreted VTG-like protein. Electrophoretical analysis of the secretory products revealed the induction of a group of phosphoproteins immunologically related to yolk lipovitellin whose molecular weights range from 116,000 to 200,000.     

Expression of allatostatins in the Mediterranean field cricket, Gryllus bimaculatus de Geer (Ensifera, Gryllidae)

The allatostatin (AST) type A gene of the cricket Gryllus bimaculatus encodes a hormone precursor including at least 14 putative peptides with a common C-terminus Y/FXFGL/Iamide. By RT-PCR we have analyzed the expression of the allatostatin precursor in various tissues of 0-21 days old adult virgin and mated females. In 3-day-old virgin females, the gene is strongly expressed in the brain (oesophageal ganglion), the suboesophageal ganglion and the caecum, but to a lower extent in other parts of the digestive tract (ileum, midgut, colon), and in various other tissues such as the fat body, ovaries and female accessory reproductive glands. In the brain and ovaries of virgin females, the AST expression is rather constant throughout adult life, whereas in brains of mated animals, expression is low until day 7, but increases sharply from day 8 onwards to reach values triple those before day 7. In ovaries of mated animals AST gene expression is also age-dependent, with high expression rates during the first 4 days after imaginable moult, a second but smaller peak from day 15 to 21, and very low values in between. In the fat body of virgin crickets allatostatin expression is high during the first 9 days after ecdysis and declines thereafter, whereas in mated animals two peak values, day 1 and day 6, are observed, and a third peak in older animals.     

The influence of host sex on the L3 to L4 molt of Brugia malayi

Immunocompetent male mice are more susceptible to experimental infection with Brugia spp. than are females. Because permissive male SCID mice (severe combined immunodeficient mice), which lack T and B cells, also possess higher worm burdens, the mechanism is not solely immune mediated. Recovery of fewer adult worms from the female SCID mouse suggests that females do not provide sufficient nutrients for larval growth. This study assessed the potential of the female SCID mouse to support the L3 to L4 molt of Brugia malayi. Unexpectedly, worms grown in females molted at earlier time points of recovery than those harvested from males. This suggests that the early stage of development of B. malayi is delayed in the male murine host. To determine whether the effect of host sex on molting may be similar in humans, worms were cultured in media supplemented with serum from male or female donors. Worms grown in serum obtained from female donors exhibited a significantly higher percentage of complete molts over those cultured with serum from males. Host-derived molecules required for the L3 to L4 molt may be more abundant in the female, perhaps allowing the worms to survive a vulnerable developmental stage in a less permissive environment.     

Developmental effects of testosterone on behavior in male and female green anoles (Anolis carolinensis)

This study addressed the role of testosterone (T) in the development of sexually dimorphic behavior in the green anole lizard, Anolis carolinensis. We documented the pattern of endogenous T concentrations during ontogeny and we determined the behavioral effects of experimentally elevated T in juvenile males and females. T concentrations were measured in the plasma of hatchlings from eggs incubated in the laboratory, in juveniles of all sizes sampled in the field, and in the yolks of freshly laid eggs in the laboratory and were compared to plasma T in adult females (measured in this study) and adult males. There were no sex differences in plasma T in hatchling and small juvenile (<26-mm snout-vent length, SVL; <14 days old) males and females, concentrations of which in both sexes tended to decline over the 14-day posthatching period. Plasma T sharply increased in juvenile males, but not females, after approximately 14 days posthatching (>25-mm SVL), and it became significantly higher after approximately 38 days posthatching (>30-mm SVL). Plasma T for juvenile males was within the range detected in breeding adult females, but it was 20- to 45-fold lower than that of adult males, breeding or postbreeding. All eggs contained detectable yolk T, but eggs that gave rise to males contained nearly twice as much yolk T as those that gave rise to females. We do not know whether this yolk T comes from the mother, embryo, or both. In behavior trials conducted in the laboratory, juveniles (36- to 42-mm SVL) with T implants, regardless of whether they were male or female, had increased activity levels compared to juveniles with blank implants, due to increased rates of nearly every behavior monitored. These results are discussed in the context of the organization-activation theory of sexual differentiation and the particular life history of A. carolinensis.     

Sexual immaturity and maternal age: incidence of aneuploidy and polyploidy in first-cleavage mouse embryos

The influence of maternal age on the incidence of aneuploidy and polyploidy was studied, using C57Bl/6J X CBA/Ca hybrid mice, including immature females, as gamete donors. The age of the females ranged from 3.5-4 wk (immature or prepubertal), to 10-12 wk (young adults), to 24-28 wk (aged females). Ovulation was induced with gonadotrophins, and the differential condensation of paternal and maternal chromosomes was used to elucidate the origin of chromosome abnormalities in first-division metaphase plates. The results indicated a high incidence of aneuploid oocytes in immature and older female mice, as compared to young adult females. Eggs of immature female mice underwent polyspermic fertilization more often than those of young adults and older females, and the production of diploid oocytes was more frequent in immature females than in the other age groups.     

Juvenile hormone-dependent vitellogenin synthesis in Locusta migratoria fat body: Inducibility related to sex and stage

Juvenile hormone (JH)-dependent vitellogenin (Vg) synthesis in the fat body of Locusta migratoria is normally limited to sexually mature adult females. As a step toward examining the basis of this limitation, we have tested female and male locusts in a series of stages after the third larval molt for inducibility of Vg synthesis by the synthetic JH analog, methoprene. We find that in the fourth and fifth larval instars fat body of both sexes can be induced to produce Vg, but in the adult stage females respond strongly while no more than trace amounts can be induced in males. Quantitative assays show relative responsiveness in the order: adult female > fifth instar female > fifth instar male ? adult male. During the fifth instar of both sexes, maximal vitellogenic response was obtained in midinstar. After the larval-adult ecdysis, female fat body was unresponsive during the first 4 days, then responsiveness increased and by Day 8 after ecdysis fat bodies were fully as competent to produce Vg as at Day 14, the usual maximum of the first vitellogenic cycle due to endogenous JH. Larval and adult female fat bodies implanted into male larvae are competent for Vg synthesis after metamorphosis, so that the differences between adult male and female cannot be imposed by the male milieu intérieur during the larval-adult molt. In male and female precocious adults, produced by treatment of fourth instars with precocene, fat body responded to methoprene as in normal adults. We conclude that factors intrinsic to the fat body cells, determined early in development, are responsible for differential gene programing in males and females, which is partially expressed by the fifth instar but fully manifest only after a molt in the absence of JH.     

不同性别和年龄的大仓鼠对黄鼬气味的反应

将雌性成体和雌雄亚成体大仓鼠 (Cricetulustriton)长期 (4周 )暴露给过量的黄鼬 (Mustelasibirica)肛腺分泌物 ,观察其行为和生理状态的变化 ,并通过与我们以前有关黄鼬气味对成年雄鼠影响的研究结果进行比较 ,表明黄鼬气味对不同性别和不同年龄大仓鼠的胁迫效应和生殖抑制存在差异。发现黄鼬气味对雌性大仓鼠的影响较雄性小 ,对亚成体的影响较成体小 ,这与雌性和未成年动物对各种胁迫因素的反应更敏感的普遍现象相反。在成年鼠中 ,雌雄鼠的攻击行为都受到黄鼬气味的抑制 ;但天敌气味使雌性的胁腺膨大 ,对胁腺标记和肾上腺大小无影响 ;成年雄鼠的肾上腺膨大 ,胁腺萎缩 ,标记减少。在亚成体中 ,除了雄性胁腺受到抑制(与成年雄鼠相同 )外 ,雌雄鼠的肾上腺和雌性的胁腺未受影响。亚成体实验鼠的体重都比对照组低 ,但成年鼠的体重未受影响。另外 ,与以往对其它鼠类的研究结果一致 ,天敌气味并不影响成年鼠的生殖器官 ,却抑制了未成年雄鼠的附睾和未成年雌鼠的子宫。这些差异可能和生理基础的性二态以及可能面临的被捕食风险大小有关     

Dominant lethal assay of some hair-dye components in random-bred male rats.

Male rats were exposed to maximally tolerated doses of 5 hair-dye components in a dominant lethal test. Each component was tested at 3 dosage levels with 15 random-bred male rats per level. The highest dose, selected on the basis of subacute toxicity testing, generally reduced weight gains without being lethal. Freshly prepared solutions were injected i.p. at 1 ml/kg 3 times a week for 10 weeks. Rats injected with dimethylsulfoxide and triethylenemelamine served as solvent and positive controls, respectively. A majority of rats survived the treatment at the levels tested and were mated to two virgin females each per week for 2 weeks. The females were sacrificed at midterm of pregnancy and examined for live and dead implants. Dominant lethality was evaluated on the basis of 4 criteria: dead implants per pregnant female, dead implants per total implants, proportion of females with one or more dead implants, and proportion of females with two or more dead implants. 2-Nitro-p-phenylenediamine, 2,4-diaminoanisole sulfate and 2,5-diaminoanisole sulfate produced negative responses, whereas m-phenylenediamine and 4-nitro-o-phenylenediamine induced weak dominant lethality in the first trial. On retesting these weakly positive components, both m-phenylenediamine and 4-nitro-o-phenylenediamine produced negative responses.     

The Role of Juvenile Hormones in Crustacean Reproduction

SYNOPSIS. Similar to juvenile hormone production in adult insects,the production of methyl farnesoate (MF) seems to be relatedto reproduction in both sexes in mature crustaceans. The mandibularorgan (MO) synthesizes MF, and its activity corresponds to reproductivestages. High MF levels in the blood are found in vitellogenicfemales and reproductively active males. Conversely, low levelsare found in immature females, non-vitellogenic females, andmales that are in reproductive diapause. The MO is under inhibitorycontrol by neurosecretory factors from the sinus gland locatedin the eyestalks, and may be stimulated by factors from thebrain and/or thoracic ganglion.     

Binding sites of Drosophila melanogaster sex peptide pheromones

Drosophila melanogaster sex peptide (SP) and Ductus ejaculatorius peptide (DUP99B) are male pheromones transferred in the seminal fluid to the female during copulation. Both reduce sexual receptivity and stimulate oviposition in females. The presence of high-affinity SP and DUP99B binding sites in the female were investigated by incubation of cryostat tissue sections with (125)I-iodinated peptides and subsequent autoradiography. We found that in adult females radiolabeled SP and DUP99B bind to peripheral nerves, the subesophageal ganglion, the cervical connective, to discrete parts of the thoracic ganglion, and to the genital tract. Weak and uniform labeling was detected in the neuropil of the brain and the thoracic ganglion. The labeling pattern in the nervous system suggests binding of the peptides to sensory afferents or glial cells. Scatchard analysis of the binding of (125)I-DUP99B to antennal nerves yielded a dissociation constant K(d) of 6.4 nM. Competition experiments with peptide fragments show that the peptides bind with their homologous C-terminal regions. Binding sites in the nervous system of females are established throughout sexual maturation. Prominent binding of the peptides to afferent nerves suggests modification of sensory input.     

Effects of age, dominance, and seasonal changes on proximity relationships in female Japanese macaques (Macaca fuscata) in a free-ranging group at Katsuyama

The present study compares the behavior of old female Japanese macaques (Macaca fuscata) with that of their full adult daughters in a free-ranging group, with respect to dominance and seasonal changes. Old mothers (21 to 25 years old) spent more time resting and alone than did their middle-aged adult daughters (10 to 17 yr old). However, the number of skin-related animals in proximity to the subject females, did not differ between mothers and their adult daughters. Mothers maintained proximity to more non-kin-related immature animals in the mating season than did their adult daughters, perhaps to avoid sexual aggression from males and to reduce the loss of body temperature in the cold. Dominance rank clearly influenced the social interactions of old mothers: high-ranking mothers interacted with more non-related adult females and immature animals than did low-ranking mothers, indicating that old age does not decrease the attractiveness of high-ranking animals.     

Increased SCE levels in Mediterranean Italian buffaloes affected by limb malformation (transversal hemimelia)

In recent years some buffalo farms in Campania have reported the birth of calves with limb malformation, especially with transversal hemimelia. We investigated 20 Mediterranean Italian buffaloes (8 males and 12 females) from one day to six months of age, of which 10 were affected by transversal hemimelia (group 1) and 10 were healthy controls (group 2). The following clinical and radiological patterns were observed in the malformed animals: hind limbs amputated, the right amputated off the second tarsus bones and the left amputated off the proximal epiphysis metatarsus, and the right thoracic limb hypoplasic (1 female); left hind limb amputated off the proximal epiphysis metatarsus (2 females and 1 male); left hind limb amputated off the third tarsus bones (1 female); left hind limb amputated off the tibia (1 female and 1 male); left hind limb amputated off the distal epiphysis metatarsus (1 female); left hind limb amputated off the first phalanx (1 male); right hind limb amputated off the proximal epiphysis metatarsus (1 male). In their malformed limbs all the animals presented more or less developed outlines of claws. The mean rate of SCE/cell in animals with transversal hemimelia was 8.80 +/- 3.19, that of the controls 6.61 +/- 2.73. The difference was statistically significant (P < 0.001).     

Ontogenetic changes and the stability of rhesus monkey dominance relationships

Dominance relationships were studied in a rhesus monkey group during five consecutive years. The group consisted of eight stable matriarchies and an adult male class which was replaced at the start, and again at the midpoint, of the study. Immature males were selectively harvested to maintain a sex ratio typical of natural troops. Maximum group size during the study was 77 animals.Dominance relationships were remarkably stable, with only 4.4% of dyads failing to show unidirectional relationships. Despite this stability, a linear ranking of all group members was not possible. Male dominance relationships with other males were among the most stable, following the fighting which ensued on male introductions. Male introductions did not disrupt female dominance relationships.Adult female dominance relationships were also quite stable, but immature females slowly achieved dominance over older sisters and females subordinate to their mothers. Such reversals were the result of processes lasting over many months. Many dominance assertions occurred prior to puberty but a significant number occurred following sexual maturity. Maturing females did not reverse dominance relationships according to any particular hierarchial order and, as a consequence, many were subordinate to animals that were dominated by others that they dominated.Although there was an alpha male that was dominant to all animals in the group, adult females dominated most adult males. Adult males, however, often reciprocated aggression directed at them. They almost invariably threatened or countercharged aggressive immature animals regardless of matriarchial membership. Adult males dominated some adult and most young females, even in families containing matriarchs and adult females to which the adult males always submitted.The dominance relationships of young males were similar to those of their sisters, until puberty. Young males did not necessarily bypass adult males that their mothers outranked, and often failed to win against adult females that their mothers dominated. Adolescent female aggression against females is seldom interfered with by adult males, and females may actively aid one another against males. In contrast, the aggression of young males often elicits interference by adult males, and young males often become the targets of redirected aggression in the group. As a consequence, whereas young females rise in rank to positions adjacent to their mothers, adolescent males often suffer losses to animals that they had dominated as juveniles.     

Testosterone-induced changes in adult canary brain are reversible

Brain nuclei that control song are larger in male canaries, which sing, than in females, which sing rarely or not at all. Treatment of adult female canaries with testosterone (T) induces song production and causes song-control nuclei to grow, approaching the volumes observed in males. For example, the higher vocal center (HVC) of adult females approximately doubles in size by 1 month following the onset of T treatment. Male HVC projects to a second telencephalic nucleus, RA (the robust nucleus of the archistriatum), which projects in turn to the vocal motor neurons. Whether HVC makes a similar connection in female canaries is not known, although HVC and RA are not functionally connected in female zebra finches, a species in which testosterone does not induce neural or behavioral changes in the adult song system. This experiment investigated whether HVC makes an efferent projection to RA in normal adult female canaries, or if T is necessary to induce the growth of this connection. In addition, we examined whether T-induced changes in adult female canary brain are reversible. Adult female canaries received systemic T implants that were removed after 4 weeks; these birds were killed 4 weeks after T removal (Testosterone-Removal, T-R). Separate groups of control birds received either (a) T implants for 4 weeks which were not removed (Testosterone-Control, T-C) or (b) empty implants (Untreated Control, øO-C). Crystals of the fluorescent tracer DiI were placed in the song-control nucleus HVC in order to anterogradely label both efferent targets of HVC, RA and Area X. Projections from HVC to RA and Area X were present in all treatment groups including untreated controls, and did not appear to differ either qualitatively or quantitatively. Thus, formation of efferent connections from HVC may be prerequisite to hormone-induced expression of song behavior in adult songbirds. The volumes of RA and Area X were measured using the distribution of anterograde label as well as their appearance in Nissl-stained tissue. RA was larger in T-treated control birds than in untreated controls. Experimental birds in which T was given and then removed (T-R) had RA volumes closer in size to untreated controls (ø-C). Because the volume of RA in T-treated controls (T-C) was larger than that of birds that did not receive T (ø-C), we conclude that the volume of RA increased in both T-C and T-R birds but regressed upon removal of T in T-R birds. Surprisingly, the volume of Area X did not increase in T-treated birds. Birds in this study were maintained on short days, suggesting that T-induced growth of Area X reported previously may have resulted from an interaction between T and another seasonal or photoperiodic factor induced by exposure to long daylengths. © 1993 John Wiley & Sons, Inc.     

In vitro Cultivation of the Entomogenous Nematode Filipjevimermis leipsandra

The mermithid nematode, Filipjevimermis leipsandra, was successfully cultivated to the preadult stage in Schneider''s Drosophila medium supplemented with 20% fetal bovine serum. Upon transfer to a solid substrate the preadults continued to develop into ovipositing adult females. Four molts were observed. The first molt occurred in the egg. The second occurred after 6-8 days in culture during which the very thin cuticle was shed completely. The third molt occurred after 18-20 days in culture; the cuticle was retained by the third-stage nematode. This stage was considered comparable to the preadult stage that emerges from host larva, Diabrotica spp. The fourth molt occurred within 12 days after the preadult was transferred from the liquid medium to a solid substrate. Adult females began ovipositing viable eggs 1-3 days after the final molt.     

Localization of vitellogenin mRNA expression and vitellogenin uptake during ovarian maturation in the giant freshwater prawn Macrobrachium rosenbergii

In situ hybridization and immunohistochemical techniques were used to investigate the dynamics of vitellogenin (Vg) mRNA expression and Vg uptake during ovarian maturation in the hepatopancreas and ovary at differing stages of ovarian maturation in both intact and eyestalk ablated female Macrobrachium rosenbergii. In the hepatopancreas of intact animals, Vg mRNA expression was detected faintly two days after ecdysis, and signals showed a gradual increase as the molt cycle advanced to the premolt stages, but decreased at the late premolt stage. Vg mRNA was detected in the R-cells of the hepatopancreas, indicating that these cells are responsible for synthesizing Vg. No Vg mRNA expression was observed in the ovary. Immunohistochemistry results for the hepatopancreas showed a pattern of staining intensity similar to that of in situ hybridization. Increases in the accumulation of yolk protein in the oocytes occurred concomitantly with increasing Vg mRNA expression. In eyestalk ablated animals, Vg mRNA expression and Vg uptake showed similar but accelerated patterns to those of intact animals. This study has confirmed on the cellular level previous results that Vg synthesis is intrinsically correlated to ovarian maturation and the molt cycle in M. rosenbergii.