Ovarian follicular response of mares to GnRH agonist (leuprolide acetate) treatment after pituitary suppression

Follicular growth and ovulation were monitored in 18 horse mares during a control cycle and during a cycle in which the mares received a GnRH agonist, leuprolide acetate (LA; 200 or 400 mug), twice daily until ovulation. Prior to both of these cycles, follicular growth was suppressed using a 10-day estrogen-progesterone treatment regimen, with prostaglandin F-2alpha (10 mg) administered on Day 10. Four of the mares treated with LA remained anovulatory for at least 3 weeks after the end of treatment and were excluded from statistical analysis. The dosage of LA did not affect response. Treatment with LA significantly (P=0.0375) increased the percentage of large follicles per ovulation (i.e., follicles greater than 30 mm in diameter on the day on which the largest follicle reached 35 mm) and also increased (P=0.0539) the diameter of the second largest follicle. However LA did not significantly alter the number of ovulations. Mean daily concentrations of luteinizing hormone (LH) were not significantly different during treatment and control cycles. The LH in blood samples collected repeatedly on Day 19 after the start of estrogen-progesterone treatment did not show a difference in frequency or amplitude of pulses between treatment and control cycles. Mares were artificially inseminated during estrus and the embryos were recovered. Fewer embryos were recovered per ovulation from mares after treatment with LA (26%) than during the control cycle (64%). Results indicate that treatment with LA either suppressed follicular activity or induced multiple follicular growth.     

Further segregation analysis of the fragile X syndrome with special reference to transmitting males

Summary A new series of 96 pedigrees with the fra(X) syndrome was analysed using complex segregation analysis with pointers, defining affection as any degree of mental impairment. These families were found to exhibit the same segregation pattern as the first series of 110 pedigrees (Sherman et al. 1984). The best estimate for penetrance of mental impairment in males was 79% and in females was 35% for the combined data. Again, there was little evidence for sporadic cases among affected males.Many more intellectually normal transmitting males have been observed since the existence of such males and the concomitant need to investigate the paternal side of pedigrees was recognized. On further investigation of all 206 pedigrees from the old and new data sets, the sibships of nonexpressing males appeared to be different from those of expressing males. Our analysis, using mental impairment as the phenotype, suggested that obligate carrier mothers and daughters of intellectually normal transmitting males are rarely, if ever, mentally impaired and that the sibs of transmitting males are much less likely to be retarded than the sibs of mentally impaired males. Though mothers and daughters of transmitting males are similar in phenotype, the expression of the gene in their offspring appears to be different: the penetrance of mental impairment is higher in offspring of intellectually normal daughters of transmitting males than in offspring of intellectually normal mothers of transmitting males. The implications of these observations for genetic counseling and for genetic models of the fra(X) syndrome are discussed.     

Problems with areal definitions of endemism: the effects of spatial scaling

The concept of endemism is useful in quantifying the biological uniqueness of an area, and has been used by many authors as a meaningful alternative to simple species richness. The traditional definition of endemism includes those species with ranges restricted to a particular region, and therefore is useful only in reference to that region. To compare different regions, however, a standardized approach is required, so several authors began using area-based definitions. Accordingly, those species with ranges smaller than a particular area (e.g. 50,000 km ²) are deemed endemic. Nevertheless, several problems are associated with this approach: as the area threshold changes, scaling of endemism also changes, producing a different picture of endemism for each spatial scale. Moreover, the areal definition assumes equal levels of heterogeneity in different landscapes (clearly a simplification), which overemphasizes fine-grained regions. Herein, the importance of distinguishing the regional definition (endemism) from the areal definition (range restriction) is emphasized, and investigators are encouraged to consider multiple spatial scales and geographic dimensions in evaluations of biodiversity.     

The lectotype of Sphenobaiera Ikorfatensis (Seward) Florin, a ginkgophyte from the Lower Cretaceous of western Greenland

Use of the genus Sphenobaiera Florin for deeply divided ginkgoalean leaves lacking a petiole is discussed. The type material of the species Sphenobaiera ikorfatensis (Seward) Florin from the Lower Cretaceous at Ikorfat in West Greenland is diagnosed, redescribed and the lectotype designated. The cuticle, which is described and figured in detail for the first time, shows the leaf to be amphistomatic and allows previous identifications of Sphenobaiera ikorfatensis in Lower Cretaceous floras from Siberia and China to be confirmed.     

Stress amplifies sex differences in primate prefrontal profiles of gene expression

Background

Stress is a recognized risk factor for mood and anxiety disorders that occur more often in women than men. Prefrontal brain regions mediate stress coping, cognitive control, and emotion. Here, we investigate sex differences and stress effects on prefrontal cortical profiles of gene expression in squirrel monkey adults.

Methods

Dorsolateral, ventrolateral, and ventromedial prefrontal cortical regions from 18 females and 12 males were collected after stress or no-stress treatment conditions. Gene expression profiles were acquired using HumanHT-12v4.0 Expression BeadChip arrays adapted for squirrel monkeys.

Results

Extensive variation between prefrontal cortical regions was discerned in the expression of numerous autosomal and sex chromosome genes. Robust sex differences were also identified across prefrontal cortical regions in the expression of mostly autosomal genes. Genes with increased expression in females compared to males were overrepresented in mitogen-activated protein kinase and neurotrophin signaling pathways. Many fewer genes with increased expression in males compared to females were discerned, and no molecular pathways were identified. Effect sizes for sex differences were greater in stress compared to no-stress conditions for ventromedial and ventrolateral prefrontal cortical regions but not dorsolateral prefrontal cortex.

Conclusions

Stress amplifies sex differences in gene expression profiles for prefrontal cortical regions involved in stress coping and emotion regulation. Results suggest molecular targets for new treatments of stress disorders in human mental health.

     

Fouling of nanostructured insect cuticle: adhesion of natural and artificial contaminants

The adhesional properties of contaminating particles of scales of various lengths were investigated for a wide range of micro- and nanostructured insect wing cuticles. The contaminating particles consisted of artificial hydrophilic (silica) and spherical hydrophobic (C(18)) particles, and natural pollen grains. Insect wing cuticle architectures with an open micro-/nanostructure framework demonstrated topographies for minimising solid-solid and solid-liquid contact areas. Such structuring of the wing membranes allows for a variety of removal mechanisms to contend with particle contact, such as wind and self-cleaning droplet interactions. Cuticles exhibiting high contact angles showed considerably lower particle adhesional forces than more hydrophilic insect surfaces. Values as low as 3 nN were recorded in air for silica of ~28 nm in diameter and <25 nN for silica particles 30 μm in diameter. A similar adhesional trend was also observed for contact with pollen particles.     

C-banding patterns in the AustralianBulbine (Liliaceae): The annual group,B. semibarbata s. lato

Chromosome C-band patterns have been studied in 34 populations of the Australian annualBulbine group, which comprises 4x (2n = 26, 28), 8x (2n = 52, 54) and 12x (2n = 78) populations. The 2n = 26B. semibarbata populations have a simple, low heterochromatin pattern with very minor polytypic variation. The 2n = 28 populations, corresponding morphologically to a group given separate status asB. alata, are similar in pattern but exhibit pronounced enhancement of telomeric and, more particularly, centromeric dot bands. NOR heterochromatin and satellites are difficult to identify inB. alata but appear to occur in different positions from the 26-chromosome karyotype. Eastern Australian 8 x patterns are consistent with a proposed hybrid ancestry,B. semibarbata ×B. alata. Annual and perennial C-band profiles in the AustralianBulbine are discussed briefly in relation to the additive and transformation models of heterochromatin evolution and to the possible adaptive significance of variation in heterochromatin content.Cytoevolution in the AustralianBulbine 2; for part 1 see Pl. Syst. Evol.157, 201–217.     

Processive Endoglucanases Mediate Degradation of Cellulose by Saccharophagus degradans

Bacteria and fungi are thought to degrade cellulose through the activity of either a complexed or a noncomplexed cellulolytic system composed of endoglucanases and cellobiohydrolases. The marine bacterium Saccharophagus degradans 2-40 produces a multicomponent cellulolytic system that is unusual in its abundance of GH5-containing endoglucanases. Secreted enzymes of this bacterium release high levels of cellobiose from cellulosic materials. Through cloning and purification, the predicted biochemical activities of the one annotated cellobiohydrolase Cel6A and the GH5-containing endoglucanases were evaluated. Cel6A was shown to be a classic endoglucanase, but Cel5H showed significantly higher activity on several types of cellulose, was the highest expressed, and processively released cellobiose from cellulosic substrates. Cel5G, Cel5H, and Cel5J were found to be members of a separate phylogenetic clade and were all shown to be processive. The processive endoglucanases are functionally equivalent to the endoglucanases and cellobiohydrolases required for other cellulolytic systems, thus providing a cellobiohydrolase-independent mechanism for this bacterium to convert cellulose to glucose.The microbial degradation of cellulose is of interest due to applications in the sugar-dependent production of alternative biofuels (25). There are well-characterized cellulolytic systems of bacteria and fungi that employ multiple endo-acting glucanases and exo-acting cellobiohydrolases in the degradation of cellulose (12). For example, the noncomplexed cellulase system of the wood soft rot fungus Hypocrea jecorina (anamorph Trichoderma reesei), the source for most commercially available cellulase preparations, produces up to eight secreted β-1,4-endoglucanases (Cel5A, Cel5B, Cel7B, Cel12A, Cel45A, Cel61A, Cel61B, and Cel61C), two cellobiohydrolases (Cel6A and Cel7A), and several β-glucosidases (e.g., Bgl3A) (21). Cellobiohydrolases are critical to the function of these systems, as, for example, Cel7A comprises in excess of 50% of the cellulases secreted by this organism (11). Another well-characterized noncomplexed cellulase system is found in Thermobifida fusca, a filamentous soil bacterium that is a major degrader of organic material found in compost piles (32). This bacterium also secretes several endoglucanases and end-specific cellobiohydrolases to degrade cellulose (32). An alternative mechanism for degradation of cellulose is found in microorganisms producing complexed cellulolytic systems, such as those found in cellulolytic clostridia. In these microorganisms, several β-1,4-endoglucanases and cellobiohydrolases assemble on surface-associated scaffoldin polypeptides to form cellulose-degrading multiprotein complexes known as cellulosomes (2, 6). The unifying theme in both complexed and noncomplexed systems is the importance of cellobiohydrolases in converting cellulose and cellodextrins to soluble cellobiose.Recently, a complete cellulolytic system was reported to occur in the marine bacterium Saccharophagus degradans 2-40 (28, 31). This bacterium is capable of growth on both crystalline and noncrystalline celluloses as sole carbon sources and produces multiple glucanases that can be detected in zymograms of cell lysates (28). The genome sequence of this bacterium predicts that the cellulolytic system of this bacterium consists of 10 GH5-containing β-1,4-endoglucanases (Cel5A, Cel5B, Cel5C, Cel5D, Cel5E, Cel5F, Cel5G, Cel5H, Cel5I, and Cel5J), two GH9 β-1,4-endoglucanases (Cel9A and Cel9B), one cellobiohydrolase (Cel6A), five β-glucosidases (Bgl1A, Bgl1B, Bgl3C, Ced3A, and Ced3B), and a cellobiose phosphorylase (Cep94A) (28, 31). The apparent absence of a homolog to a scaffoldin in the genome sequence and to dockerin-like domains in the proposed glucanases suggests that this bacterium produces a noncomplexed cellulolytic system. Two unusual features of this cellulolytic system are the large number of GH5 endoglucanases and the presence of only one annotated cellobiohydrolase, Cel6A (28, 31). The apparent deficiency of cellobiohydrolases in this system raised the question as to the mechanism by which this bacterium degrades cellulose.To understand the mechanism for degradation of cellulose, the biochemical activities for the predicted cellobiohydrolase Cel6A and each of the GH5 glucanases predicted for the S. degradans cellulolytic system were evaluated. Cel6A exhibited properties of a classic endoglucanase, but three of the originally annotated endoglucanases, Cel5G, Cel5H, and Cel5J, were shown to be processive, forming cellobiose as the end product. Processive endoglucanases substitute for cellobiohydrolases in this system to play a major role in the degradation of cellulose.