Four new species of Hydnellum (Thelephorales, Basidiomycota) with a note on Sarcodon illudens.

Four new Hydnellum species are described. Hydnellum roseoviolaceum sp. nov. grows in dry pine heaths on acidic, sandy soil. It is close to H. fuligineoviolaceum, another pine-associated species, but differs by smaller spores, an initially rose-coloured instead of violet flesh in fresh basidiomata and a mild taste. Hydnellum scabrosellum sp. nov. grows in coniferous forests on calcareous soil. It shares a general morphology with H. scabrosum, which also is its closest relative. It differs by having smaller and slenderer basidiomata and by the yellowish ochraceous colour of flesh and spines in dried specimens compared to the whitish or reddish brown colour seen in H. scabrosum. Hydnellum fagiscabrosum sp. nov. is another species with morphological and phylogenetic affinities to H. scabrosum. However, it is associated with trees from Fagales whereas H. scabrosum is associated with Pinaceae. Hydnellum nemorosum sp. nov. is yet another species that associates with broadleaved trees. It seems to be a rare species, morphologically reminiscent of H. fuligineoviolaceum, H. ioeides and H. scabrosum, but it is phylogenetically close to H. fennicum. Sequences from the type specimens of H. glaucopus, H. lepidum, H. scabrosum, Sarcodon illudens and S. regalis are included in the analyses. Specimens given the provisional name "Sarcodon pseudoglaucopus" in Sweden are now shown to be referable to S. illudens. The analyses further showed that S. illudens is close to H. lepidum. The new combination Hydnellum illudens is proposed. Sarcodon regalis and H. lepidum are shown to be conspecific and, although their basionyms were simultaneously published, the name S. regalis was only validated in a later publication. Hydnellum lepidum therefore takes priority and S. regalis becomes a synonym. Citation: Nitare J, Ainsworth AM, Larsson E, Parfitt D, Suz LM, Svantesson S, Larsson K-H (2021). Four new species of Hydnellum (Thelephorales, Basidiomycota) with a note on Sarcodon illudens. Fungal Systematics and Evolution 7: 233-254. doi: 10.3114/fuse.2021.07.12.

A high-entropy manganite in an ordered nanocomposite for long-term application in solid oxide cells.

The implementation of nano-engineered composite oxides opens up the way towards the development of a novel class of functional materials with enhanced electrochemical properties. Here we report on the realization of vertically aligned nanocomposites of lanthanum strontium manganite and doped ceria with straight applicability as functional layers in high-temperature energy conversion devices. By a detailed analysis using complementary state-of-the-art techniques, which include atom-probe tomography combined with oxygen isotopic exchange, we assess the local structural and electrochemical functionalities and we allow direct observation of local fast oxygen diffusion pathways. The resulting ordered mesostructure, which is characterized by a coherent, dense array of vertical interfaces, shows high electrochemically activity and suppressed dopant segregation. The latter is ascribed to spontaneous cationic intermixing enabling lattice stabilization, according to density functional theory calculations. This work highlights the relevance of local disorder and long-range arrangements for functional oxides nano-engineering and introduces an advanced method for the local analysis of mass transport phenomena.

Early clinical failure of the ACCIS® metal on metal hip arthroplasty system - A metal on metal hip with a difference.

The ACCIS hip system has been marketed with a unique bearing surface which the manufacturers claim to reduce wear below the level of other MoM bearings and consequently less metal ion release. The cobalt-chrome-molybdenum alloy is heat treated to reduce the number and size of block carbides and the surface is modified with titanium-niobium-nitride to create a ceramic-like surface. We present our experience with ACCIS. 148 surgical procedures were carried out in 126 patients using the ACCIS hip resurfacing (77) or large head MOM total hip replacement(71). Patients were followed up with regular clinical and radiological assessment. In addition, metal ion levels were obtained. There have been 27 revision procedures carried out for a variety of indications with a current revision rate of 18%. Seven failures could not be attributed to the prosthesis itself, still leaving a failure rate of 13.5%. The mean survival time of these is 33 months, ranging from 1 to 72 months. 13 revisions were -performed for pain and revision demonstrated poor cup integration. 7 were revised because of high ion levels but this was patient choice despite remaining asymptomatic. Whilst the testing phases indicated benefits in wear characteristics, this is not apparent in our group. We have demonstrated an unacceptably high revision rate due to unknown causes and have ceased implanting the ACCIS.

Characterisation of interfacial segregation to Cu-enriched precipitates in two thermally aged reactor pressure vessel steel welds.

To understand the contribution of long term thermal ageing to Reactor Pressure Vessel (RPV) embrittlement two high Cu steel welds with different Ni contents were thermally aged for times up to 100,000 h at 330 °C and 365 °C. Microstructural characterisation using Atom Probe Tomography was performed. Thermal ageing produced a high number density of nano-scale Cu-enriched precipitates. The precipitate-matrix interfaces were enriched in Ni, Mn and Si. The characterisation of these interfaces using a double cluster search approach is the subject of this work. The interface region around thermally-induced precipitates was found to be wider in steels with higher bulk Ni contents and where precipitates had larger core radii. The effect of ageing temperature on interface width was small when comparing precipitates of equal core radius. The narrower interface width in the lower Ni steels is reflected in the composition of the interface, which has a lower Ni content than in the higher Ni material. The reduction in interfacial energy due to the segregation of Ni, Mn and Si has been calculated and shows enhanced reductions in interfacial energy with increasing precipitate size, but no obvious effect of temperature.

The heat-shock response co-inducer arimoclomol protects against retinal degeneration in rhodopsin retinitis pigmentosa.

Retinitis pigmentosa (RP) is a group of inherited diseases that cause blindness due to the progressive death of rod and cone photoreceptors in the retina. There are currently no effective treatments for RP. Inherited mutations in rhodopsin, the light-sensing protein of rod photoreceptor cells, are the most common cause of autosomal-dominant RP. The majority of mutations in rhodopsin, including the common P23H substitution, lead to protein misfolding, which is a feature in many neurodegenerative disorders. Previous studies have shown that upregulating molecular chaperone expression can delay disease progression in models of neurodegeneration. Here, we have explored the potential of the heat-shock protein co-inducer arimoclomol to ameliorate rhodopsin RP. In a cell model of P23H rod opsin RP, arimoclomol reduced P23H rod opsin aggregation and improved viability of mutant rhodopsin-expressing cells. In P23H rhodopsin transgenic rat models, pharmacological potentiation of the stress response with arimoclomol improved electroretinogram responses and prolonged photoreceptor survival, as assessed by measuring outer nuclear layer thickness in the retina. Furthermore, treated animal retinae showed improved photoreceptor outer segment structure and reduced rhodopsin aggregation compared with vehicle-treated controls. The heat-shock response (HSR) was activated in P23H retinae, and this was enhanced with arimoclomol treatment. Furthermore, the unfolded protein response (UPR), which is induced in P23H transgenic rats, was also enhanced in the retinae of arimoclomol-treated animals, suggesting that arimoclomol can potentiate the UPR as well as the HSR. These data suggest that pharmacological enhancement of cellular stress responses may be a potential treatment for rhodopsin RP and that arimoclomol could benefit diseases where ER stress is a factor.

Dexamethasone and stressor-magnitude regulation of stress-induced transcription of HPA axis secretagogues in the rat.

Regulation of the production of hypothalamic-pituitary-adrenal (HPA) axis secretagogues, corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP), may be differentially sensitive to the negative feedback effects of glucocorticoids. We chose to study this phenomenon by examining the ability of dexamethasone to influence CRH and AVP heteronuclear RNA (hnRNA) levels in an escapable/inescapable (ES/IS) foot-shock stress paradigm. On Day 1, adult male rats were subjected to either ES or IS foot-shock; on Day 2, saline or dexamethasone (100 microg/kg) was administered 2 h prior to the stressor. We found that ES/IS foot-shock stimulated similar robust increases in plasma adrenocorticotrophic hormone (ACTH) and corticosterone concentrations, and medial parvocellular division of the paraventricular nucleus (mpPVN) AVP and CRH hnRNA and c-fos mRNA levels in saline-treated ES/IS rats. Dexamethasone pretreatment suppressed ACTH and corticosterone levels similarly in IS and ES animals. Dexamethasone pretreatment also suppressed mpPVN CRH and AVP hnRNA levels at 30 min. However, by 120 min, the mpPVN AVP hnRNA levels in dexamethasone-treated rats were similar to those measured in the saline group. We also found that rats that received the most shocks on Day 1 had greater HPA axis activation on Day 2. We conclude that the magnitude of the foot-shock stressor, determined by learned and immediate cues, is important in determining the magnitude of the HPA response.

Field note phytovolatilization of oxygenated gasoline-impacted groundwater at an underground storage tank site via conifers.

A stand of five conifers (Pinus sp.) bordering a gasoline service station was studied to estimate the methyl tert-butyl ether (MTBE) emission rate from gasoline-impacted groundwater. Groundwater was impacted with gasoline oxygenates MTBE and tert-butyl alcohol (TBA) at combined concentrations exceeding 200,000 microg/L. Condensate from trees was collected in sealed environmental chambers and analyzed. Concentrations of MTBE in condensate ranged from 0.51 to 460 microg/L; TBA ranged from 12 to 4100 microg/L (n=19). Transpirate concentrations were derived from MTBE air-liquid partitioning data exhibited in controls spiked with known concentrations of analyte. Tree emissions were estimated by multiplying average transpirate concentrations by transpiration rates derived from evapotranspiration data. Stand evapotranspiration was calculated using meteorological data from the California Irrigation Management Information System (CIMIS) applied in the Standardized Reference Evapotranspiration Equation.

Relation between the hypothalamic-pituitary-thyroid (HPT) axis and the hypothalamic-pituitary-adrenal (HPA) axis during repeated stress.

Previous work has indicated that acute and repeated stress can alter thyroid hormone secretion. Corticosterone, the end product of hypothalamic-pituitary-adrenal (HPA) axis activation and strongly regulated by stress, has been suggested to play a role in hypothalamic-pituitary-thyroid (HPT) axis regulation. In the current study, we sought to further characterize HPT axis activity after repeated exposure to inescapable foot-shock stress (FS), and to examine changes in proposed regulators of the HPT axis, including plasma corticosterone and hypothalamic arcuate nucleus agouti-related protein (AGRP) mRNA levels. Adult male Sprague-Dawley rats were subjected to one daily session of inescapable FS for 14 days. Plasma corticosterone levels were determined during and after the stress on days 1 and 14. Animals were killed on day 15, and trunk blood and brains were collected for measurement of hormone and mRNA levels. Repeated exposure to FS led to a significant decrease in serum levels of 3,5,3'-triiodothyronine (T3) and 3,5,3',5'-tetraiodothyronine (T4). Stress-induced plasma corticosterone levels were not altered by repeated exposure to the stress. Despite the decrease in peripheral hormone levels, thyrotropin-releasing hormone (TRH) mRNA levels within the paraventricular nucleus of the hypothalamus were not altered by the stress paradigm. Arcuate nucleus AGRP mRNA levels were significantly increased in the animals exposed to repeated FS. Additionally, we noted significant correlations between stress-induced plasma corticosterone levels and components of the HPT axis, including TRH mRNA levels and free T4 levels. Additionally, there was a significant correlation between AGRP mRNA levels and total T3 levels. Changes in body weight were also correlated with peripheral corticosterone and TRH mRNA levels. These results suggest that repeated exposure to mild-electric foot-shock causes a decrease in peripheral thyroid hormone levels, and that components of the HPA axis and hypothalamic AGRP may be involved in stress regulation of the HPT.

Differential expression of putative floral genes in Pharbitis nil shoot apices cultured on glucose compared with sucrose.

If, following an inductive treatment of 2 d of continuous darkness, shoot apices of Pharbitis nil are cultured 1 d later on White's medium supplemented with 2% sucrose, they cannot form carpels, but they can if they are cultured on 2% glucose. It was hypothesized that the differential effect of these sugars was because of differential expression of carpel-specific genes. Partial cDNA homologues to the Arabidopsis genes, LEAFY (PnLFY), AGAMOUS (PnAG1/2), and CRABS CLAWS (PnCRC1/2) were cloned. PnLFY was expressed in the shoot apex 1 d following the start of induction and remained higher than in non-induced apices for a further 6 d before exhibiting a major peak of expression on day 7. Peaks of expression of PnAG1 and PnAG2 spanned days 7-11, coinciding with the appearance of stamens and then carpels. The Pharbitis 'PnCRC2' showed greatest homology to Arabidopsis YABBY2 (PnYABBY). Its expression peaked on day 8 when the carpels first appeared. 'PnCRC1' showed greatest homology to Arabidopsis FILAMENTOUS (PnFIL). Its expression was approximately the same in inductive and non-inductive treatments. Apart from PnFIL these partial cDNAs could be used as markers to test the hypothesis concerning differential effects of sucrose and glucose. Cultured shoot apices from induced plants were sampled at weekly intervals. All four genes were expressed more strongly in the glucose compared with the sucrose treatment, most notably at day 17. A more intensive sampling (days 15-19) indicated that PnLFY and PnYABBY exhibited much higher expression on glucose compared with sucrose, most notably on days 15-16 and days 18-19.

Antidepressants blunt the effects of inescapable stress on male mating behaviour and decrease corticotropin-releasing hormone mRNA expression in the hypothalamic paraventricular nucleus of the Syrian hamster (Mesocricetus auratus).

Stress decreases sexual activity. However, emerging research suggests that the psychological aspect of control prevents the detrimental effects of stress on male mating behaviour. The present study examined the effects of chronic escapable/inescapable stress on mating behaviour in the male Syrian hamster. Additionally, the ability of the antidepressant clomipramine to prevent the adverse effects of stress on mating behaviour was explored. In this paradigm, two groups received the same electric footshock stress, but differed in the psychological aspect of control. Cohorts were divided into two groups. One group received clomipramine via a sugar water solution while the other received plain sugar water. Mating behaviour was quantified before and after 12 consecutive days of stress. The morning following the final stress and behaviour session, trunk blood and brains were collected to assess: (i) plasma concentrations of testosterone and glucocorticoids and (ii) corticotropin-releasing hormone (CRH) mRNA expression within the paraventricular nucleus of the hypothalamus (PVN). In the drug-free groups, several aspects of mating behaviour were disrupted by inescapable but not escapable stress, including anogenital investigation before the first ejaculation and time of first ejaculation. Additionally, both escapable and inescapable stress caused a decrease in total hit rate compared to the no-stress control group. Unlike the sugar-water treated animals, hamsters in either stress condition receiving clomipramine showed no differences in anogenital investigation, time of first ejaculation, hit rate, or any other aspect of mating behaviour measured, compared to the clomipramine no-stress control males. The stress-induced inhibition of mating behaviour could not be explained by changes in baseline plasma concentrations of testosterone or total glucocorticoids; these values did not vary between any of the six treatment groups. It was found that clomipramine lowers CRH mRNA expression in the PVN by 74%, regardless of stressor conditions. The results of the present study have broad implications for understanding the relationships between stress, depression and reproduction, and for the treatment of people and animals suffering from the adverse effects of stress.

Evidence for a causal role of low energy availability in the induction of menstrual cycle disturbances during strenuous exercise training.

Cross-sectional and short-term prospective studies in humans support the concept that low energy availability, and not other factors associated with exercise, causes the development of exercise-induced reproductive dysfunction. To rigorously test this hypothesis, we performed a longitudinal study, examining the role of low energy availability on both the development and the reversal of exercise-induced amenorrhea, using a monkey model (Macaca fascicularis). Eight adult female monkeys developed amenorrhea (defined as absence of menses for at least 100 d, with low and unchanging concentrations of LH, FSH, E2, and P4) after gradually increasing their daily exercise to 12.3 +/- 0.9 km/d of running over a 7- to 24-month period. Food intake remained constant during exercise training. To test whether amenorrhea is caused by low energy availability, four of the eight amenorrheic monkeys were provided with supplemental calories (138-181% of calorie intake during amenorrhea) while they maintained their daily training. All four monkeys exhibited increased reproductive hormone levels and reestablished ovulatory cycles, with recovery times for circulating gonadotropin levels ranging from 12-57 d from the initiation of supplemental feeding. The rapidity of recovery within the reproductive axis in a given monkey was directly related to the amount of energy that was consumed during the period of supplemental feeding (r = -0.97; P < 0.05). Repeated measurements of plasma T3 concentrations, a marker of cellular energy availability, revealed a tight correlation between the changes in reproductive function and T3 levels, such that T3 significantly decreased (27%) with the induction and significantly increased (18%) with the reversal of amenorrhea (P < 0.05). These data provide strong evidence that low energy availability plays a causal role in the development of exercise-induced amenorrhea.

Longitudinal changes in reproductive hormones and menstrual cyclicity in cynomolgus monkeys during strenuous exercise training: abrupt transition to exercise-induced amenorrhea.

Cross-sectional studies of exercise-induced reproductive dysfunction have documented a high proportion of menstrual cycle disturbances in women involved in strenuous exercise training. However, longitudinal studies have been needed to examine individual susceptibility to exercise-induced reproductive dysfunction and to elucidate the progression of changes in reproductive function that occur with strenuous exercise training. Using the female cynomolgus monkey (Macaca fascicularis), we documented changes in menstrual cyclicity and patterns of LH, FSH, estradiol, and progesterone secretion as the animals developed exercise-induced amenorrhea. As monkeys gradually increased running to 12.3 +/- 0.9 km/day, body weight did not change significantly although food intake remained constant. The time spent training until amenorrhea developed varied widely among animals (7-24 months; mean = 14.3 +/- 2.2 months) and was not correlated with initial body weight, training distance, or food intake. Consistent changes in function of the reproductive axis occurred abruptly, one to two menstrual cycles before the development of amenorrhea. These included significant declines in plasma reproductive hormone concentrations, an increase in follicular phase length, and a decrease in luteal phase progesterone secretion. These data document a high level of interindividual variability in the development of exercise-induced reproductive dysfunction, delineate the progression of changes in reproductive hormone secretion that occur with exercise training, and illustrate an abrupt transition from normal cyclicity to an amenorrheic state in exercising individuals, that is not necessarily associated with weight loss.

GnRH mRNA increases with puberty in the male Syrian hamster brain.

Puberty in the male Syrian hamster (Mesocricetus auratus) is characterized by decreased responsiveness to testosterone mediated negative feedback, but the neural mechanism for this change remains elusive. We hypothesized that decreased inhibition of the gonadotropin-releasing hormone (GnRH) system results in increased neurosecretory activity, which includes an increase in GnRH gene expression. This study examined GnRH mRNA in male hamsters before and after puberty, and sought to determine if any increase in mRNA was specific to particular subpopulations of GnRH neurones. Brains were collected from 21-day-old prepubertal males (n = 5) and 56-day-old postpubertal males (n = 5). Alternate 10 microm coronal sections from fresh-frozen brains were collected throughout the septo-hypothalamic region, and 25% of those sections were processed for in-situ hybridization histochemistry using an 35S-riboprobe complementary to hamster GnRH. No differences were observed in the number of GnRH mRNA expressing cells in any region, but in the diagonal band of Broca (DBB)/organum vasculosum of the lamina terminalis (OVLT) there was a significant increase in labelling intensity (defined as area of the cell occupied by silver grains) in postpubertal males. A second analysis compared the frequency distributions of cells based on labelling intensity between prepubertal and postpubertal males. This analysis revealed significant differences between the two frequency distributions in all areas analysed (DBB/OVLT, medial septum (MS), and preoptic area (POA)). Furthermore, examining the distribution of cells in these regions revealed a shift to the right in the postpubertal population of cells, which indicated an increased number of GnRH neurones with greater labelling intensity. These data clearly demonstrate increased GnRH mRNA during puberty. Furthermore, they suggest that the previous observation of brain region specific pubertal decreases in GnRH-immunoreactivity only within the DBB/OVLT and MS but not the POA are not due to differential levels of GnRH gene expression, but could indicate increased release from these neurones during puberty.

Fos-immunoreactivity within the extended amygdala is correlated with the onset of sexual satiety.

We hypothesized that c-fos expression in the medial amygdala (Me), the bed nucleus of the stria terminalis (BNST), and the medial preoptic area (MPOA) of the male Syrian hamster brain correlated with sexual satiety. To address this hypothesis, males were mated for 4 consecutive days. Experiment 1 determined whether the number of Fos-immunoreactive (Fos-ir) nuclei was equivalent in two groups of males mated to sexual satiety, one group of rested males (9.67 +/- 0.80 ejaculations) and a second group mated for 4 consecutive days (3.50 +/- 0.56 ejaculations). Fos-ir was increased within the caudal posterodorsal Me (cMePD), the anterodorsal and posteroventral subdivisions of the posteromedial BNST [BNSTpm(ad) and BNSTpm(pv)], the dorsolateral MPOA, and the medial preoptic nucleus of all males mated to sexual satiety compared to nonmated controls. In addition, Fos-ir "clusters" within the cMePD and BNSTpm(ad) were present in males mated to satiety regardless of the number of ejaculations. However, all males achieved multiple ejaculations. Therefore, Experiment 2 examined whether two groups of males stopped at one ejaculation exhibit different patterns of Fos-ir depending on proximity to sexual satiety. Brains of consecutively mated males, closer to satiety than rested males, showed greater BNSTpm(pv) Fos-ir and 5/6 males, but no rested male, exhibited cMePD Fos-ir clusters. These results support the hypothesis that cMePD and BNSTpm(pv) neuronal activation is associated with satiety and may constitute a discrete circuit to terminate mating.

Pheromones elicit equivalent levels of Fos-immunoreactivity in prepubertal and adult male Syrian hamsters.

Male reproductive behavior in the Syrian hamster is dependent on both pheromones from the female and the presence of gonadal steroid hormones. The pheromones are contained within female hamster vaginal secretions (FHVS) and stimulate anogenital investigation and mounting by the male. Administration of testosterone to castrated male hamsters facilitates anogenital investigation, mounts, and intromissions in adults, but elicits only anogenital investigation in prepubertal males. One hypothesis for why the full complement of reproductive behaviors is not activated by testosterone in prepubertal males is that the neural processing of pheromonal cues encountered during anogenital investigation is different in juveniles and adults. In the present experiment, we investigated the influence of sexual maturity on Fos expression in response to FHVS in the male Syrian hamster. We predicted a greater increase in Fos-immunoreactivity after exposure to FHVS within the neural circuit mediating male reproductive behaviors in adult compared to prepubertal males. Intact adult and prepubertal males were exposed to either a clean cotton swab or a swab containing FHVS. We found that, compared to animals exposed to a clean cotton swab, both prepubertal and adult males exposed to FHVS have a greater amount of Fos-immunoreactivity within several brain nuclei comprising the neural circuit mediating male reproductive behavior. Furthermore, this Fos response was equivalent in the two age groups. These results suggest that the inability of the prepubertal male hamster to perform the full repertoire of male reproductive behaviors is not due to a lack of a neuronal activation in response to the pheromonal cues present in FHVS.

Phylogeny of the genus Pistacia as determined from analysis of the chloroplast genome.

Classification within the genus Pistacia has been based on leaf morphology and geographical distribution. Molecular genetic tools (PCR amplification followed by restriction analysis of a 3.2-kb region of variable chloroplast DNA, and restriction fragment length polymorphism analysis of the Pistacia cpDNA with tobacco chloroplast DNA probes) provided a new set of variables to study the phylogenetic relationships of 10 Pistacia species. Both parsimony and cluster analyses were used to divide the genus into two major groups. P. vera was determined to be the least derived species. P. weinmannifolia, an Asian species, is most closely related to P. texana and P. mexicana, New World species. These three species share a common origin, suggesting that a common ancestor of P. texana and P. mexicana originated in Asia. P. integerrima and P. chinensis were shown to be distinct whereas the pairs of species were monophyletic within each of two tertiary groups, P. vera:P. khinjuk and P. mexicana:P. texana. An evolutionary trend from large to small nuts and leaves with few, large leaflets to many, small leaflets was supported. The genus Pistacia was shown to have a low chloroplast DNA mutation rate: 0.05-0.16 times that expected of annual plants.

Endogenous opioid peptides control the amplitude and shape of gonadotropin-releasing hormone pulses in the ewe.

This study was designed to test the hypothesis that endogenous opioid peptides (EOP) mediate the negative feedback action of estradiol on GnRH pulse size in breeding season ewes. If this hypothesis is correct, one would predict that an EOP antagonist should increase GnRH pulse size in estradiol-treated ovariectomized (OVX+E), but not in OVX, ewes. We, therefore, examined the effects of naloxone on GnRH pulse profiles in the hypophyseal portal blood of OVX and OVX+E ewes (n = 6/group). Samples were collected every 10 min for 6 h before, 6 h during, and 4 h after naloxone infusion. Estradiol treatment decreased GnRH pulse size and increased GnRH pulse frequency. Naloxone treatment had no effect on GnRH pulse frequency, but significantly increased GnRH pulse size. However, this stimulatory action of naloxone on GnRH pulse size was evident in both OVX and OVX+E ewes. These results are thus not consistent with the hypothesis that EOP mediate the negative feedback action of estradiol. Interestingly, naloxone not only increased GnRH pulse amplitude, but also prolonged the duration of GnRH release during a pulse. To obtain a more precise characterization of the effects of naloxone on the dynamics of GnRH release, pulse profiles in six OVX ewes were examined in hypophyseal portal blood sampled every minute for 4 h before and 4 h during naloxone infusion. Naloxone again increased both the amplitude and duration of GnRH pulses. The increase in GnRH pulse duration was caused by a prolongation of both the plateau and declining phases of the GnRH pulse. In addition to these effects on GnRH release during a pulse, naloxone increased the amount of GnRH collected between pulses in both experiments. The stimulatory effects of naloxone on GnRH release in OVX ewes indicate that the role of EOP in the control of GnRH is not limited to mediating the feedback actions of steroids. In particular, the dramatic effects of naloxone on GnRH pulse shape and interpulse GnRH levels raise the possibility that EOP play an important role in synchronizing the activity of the GnRH neurons involved in episodic GnRH secretion.

Phylogenetic relationships of cultivated Prunus species from an analysis of chloroplast DNA variation.

Chloroplast DNA (cpDNA) restriction-site mutations in seven cultivated Prunus species were compared to establish the phylogenetic relationships among them. Mutations were detected in 3.2-kb and 2.1-kb amplified regions of variable cpDNA, cut with 21 and 10 restriction endonucleases, respectively, to reveal polymorphisms. Parsimony and cluster analyses were performed. The species pairs P. persica-P. dulcis, P. domestica-P. salicina, and P.cerasus-P. fruticosa were completely monophyletic. All of the species were grouped with conventional subgenus classifications. The subgenus Cerasus was the most diverged. Cerasus ancestors separated from the remainder of Prunus relatively early in the development of the genus. P. persica-P. dulcis, P. domestica-P. salicina and P. armeniaca formed a second monophyletic group. Prunophora species were less diverged than Amygdalus species. The results also suggest that the rate of mutation in Cerasus spp. chloroplast genomes is significantly greater than for the other subgenera sampled.