Purification, cDNA structure and biological significance of a single insulin-like growth factor-binding domain protein (SIBD-1) identified in the hemocytes of the spider Cupiennius salei

Cupiennius salei single insulin-like growth factor-binding domain protein (SIBD-1), which exhibits an IGFBP N-terminal domain-like profile, was identified in the hemocytes of the spider C. salei. SIBD-1 was purified by RP-HPLC and the sequence determined by a combination of Edman degradation and 5'-3'- RACE PCR. The peptide (8676.08 Da) is composed of 78 amino acids, contains six intrachain disulphide bridges and carries a modified Thr residue at position 2. SIBD-1 mRNA expression was detected by quantitative real-time PCR mainly in hemocytes, but also in the subesophageal nerve mass and muscle. After infection, the SIBD-1 content in the hemocytes decreases and, simultaneously, the temporal SIBD-1 expression seems to be down-regulated. Two further peptides, SIBD-2 and IGFBP-rP1, also exhibiting IGFBP N-terminal domain variants with unknown functions, were identified on cDNA level in spider hemocytes and venom glands. We conclude that SIBD-1 may play an important role in the immune system of spiders.

Why boys will be boys: two pathways of fetal testicular androgen biosynthesis are needed for male sexual differentiation

Human sexual determination is initiated by a cascade of genes that lead to the development of the fetal gonad. Whereas development of the female external genitalia does not require fetal ovarian hormones, male genital development requires the action of testicular testosterone and its more potent derivative dihydrotestosterone (DHT). The "classic" biosynthetic pathway from cholesterol to testosterone in the testis and the subsequent conversion of testosterone to DHT in genital skin is well established. Recently, an alternative pathway leading to DHT has been described in marsupials, but its potential importance to human development is unclear. AKR1C2 is an enzyme that participates in the alternative but not the classic pathway. Using a candidate gene approach, we identified AKR1C2 mutations with sex-limited recessive inheritance in four 46,XY individuals with disordered sexual development (DSD). Analysis of the inheritance of microsatellite markers excluded other candidate loci. Affected individuals had moderate to severe undervirilization at birth; when recreated by site-directed mutagenesis and expressed in bacteria, the mutant AKR1C2 had diminished but not absent catalytic activities. The 46,XY DSD individuals also carry a mutation causing aberrant splicing in AKR1C4, which encodes an enzyme with similar activity. This suggests a mode of inheritance where the severity of the developmental defect depends on the number of mutations in the two genes. An unrelated 46,XY DSD patient carried AKR1C2 mutations on both alleles, confirming the essential role of AKR1C2 and corroborating the hypothesis that both the classic and alternative pathways of testicular androgen biosynthesis are needed for normal human male sexual differentiation.

Effects of Aerobic Versus Resistance Exercise Without Caloric Restriction on Abdominal Fat, Intrahepatic Lipid, and Insulin Sensitivity in Obese Adolescent Boys: A Randomized, Controlled Trial

The optimal exercise modality for reductions of abdominal obesity and risk factors for type 2 diabetes in youth is unknown. We examined the effects of aerobic exercise (AE) versus resistance exercise (RE) without caloric restriction on abdominal adiposity, ectopic fat, and insulin sensitivity and secretion in youth. Forty-five obese adolescent boys were randomly assigned to one of three 3-month interventions: AE, RE, or a nonexercising control. Abdominal fat was assessed by magnetic resonance imaging, and intrahepatic lipid and intramyocellular lipid were assessed by proton magnetic resonance spectroscopy. Insulin sensitivity and secretion were evaluated by a 3-h hyperinsulinemic-euglycemic clamp and a 2-h hyperglycemic clamp. Both AE and RE prevented the significant weight gain that was observed in controls. Compared with controls, significant reductions in total and visceral fat and intrahepatic lipid were observed in both exercise groups. Compared with controls, a significant improvement in insulin sensitivity (27%) was observed in the RE group. Collapsed across groups, changes in visceral fat were associated with changes in intrahepatic lipid (r = 0.72) and insulin sensitivity (r = -0.47). Both AE and RE alone are effective for reducing abdominal fat and intrahepatic lipid in obese adolescent boys. RE but not AE is also associated with significant improvements in insulin sensitivity.

Spider phobia is associated with decreased left amygdala volume: a cross-sectional study

Evidence from animal and human studies imply the amygdala as the most critical structure involved in processing of fear-relevant stimuli. In phobias, the amygdala seems to play a crucial role in the pathogenesis and maintenance of the disorder. However, the neuropathology of specific phobias remains poorly understood. In the present study, we investigated whether patients with spider phobia show altered amygdala volumes as compared to healthy control subjects.

A venom-derived neurotoxin, CsTx-1, from the spider Cupiennius salei exhibits cytolytic activities

CsTx-1, the main neurotoxic acting peptide in the venom of the spider Cupiennius salei, is composed of 74 amino acid residues, exhibits an inhibitory cysteine knot motif, and is further characterized by its highly cationic charged C terminus. Venom gland cDNA library analysis predicted a prepropeptide structure for CsTx-1 precursor. In the presence of trifluoroethanol, CsTx-1 and the long C-terminal part alone (CT1-long; Gly-45-Lys-74) exhibit an α-helical structure, as determined by CD measurements. CsTx-1 and CT1-long are insecticidal toward Drosophila flies and destroys Escherichia coli SBS 363 cells. CsTx-1 causes a stable and irreversible depolarization of insect larvae muscle cells and frog neuromuscular preparations, which seem to be receptor-independent. Furthermore, this membranolytic activity could be measured for Xenopus oocytes, in which CsTx-1 and CT1-long increase ion permeability non-specifically. These results support our assumption that the membranolytic activities of CsTx-1 are caused by its C-terminal tail, CT1-long. Together, CsTx-1 exhibits two different functions; as a neurotoxin it inhibits L-type Ca(2+) channels, and as a membranolytic peptide it destroys a variety of prokaryotic and eukaryotic cell membranes. Such a dualism is discussed as an important new mechanism for the evolution of spider venomous peptides.

To look or not to look at threat? Scanpath differences within a group of spider phobics

Predicting the behavior of phobic patients in a confrontational situation is challenging. While avoidance as a major clinical component of phobias suggests that patients orient away from threat, findings based on cognitive paradigms indicate an attentional bias towards threat. Here we present eye movement data from 21 spider phobics and 21 control subjects, based on 3 basic oculomotor tasks and a visual exploration task that included close-up views of spiders. Relative to the control group, patients showed accelerated reflexive saccades in one of the basic oculomotor tasks, while the fear-relevant exploration task evoked a general slowing in their scanning behavior and pronounced oculomotor avoidance. However, this avoidance strongly varied within the patient group and was not associated with the scores from spider avoidance-sensitive questionnaire scales. We suggest that variation of oculomotor avoidance between phobics reflects different strategies of how they cope with threat in confrontational situations.

Silhouettella loricatula (Arachnida, Araneae, Oonopidae): a Haplogyne spider with complex female genitalia

The female genital system of the oonopid Silhouettella loricatula is astonishingly complex. The genital opening is situated medially and leads into an oval receptaculum that is heavily sclerotized except for the ventral half of the posterior wall that appears chitinized only. A large striking sclerite lying in the posterior wall of the uterus externus is attached anteriorly to the receptaculum and continues dorsally into a globular appendix that bears a furrow. The uterus externus shows a peculiar modification in its anterior wall: a paddle-like sclerite with a nail-like posterior process. This sclerite lies opposite to the furrow proceeding in the globular appendix and may serve females to lock the uterus externus by muscle contractions. Massive muscles connect the sclerite with the anterior scutum of the opisthosoma and with two other sclerites that are attached to the receptaculum and serve as attachments for further muscles. Gland cells extend around a pore field of the receptaculum. They produce secretion that encloses spermatozoa in a discrete package (secretory sac) inside the receptaculum. In this way, the mixing of sperm from different males and thus sperm competition may be severely limited or completely prevented. During a copulation in the laboratory the ejection of a secretory sac that most probably contained spermatozoa was observed, indicating sperm dumping in S. loricatula. The ejection of the secretory sac may be caused by female muscle contractions or by male pedipalp movements. The majority of the investigated females have microorganisms in the receptacula that could represent symbionts or infectious agents. The microorganisms can be identified partly as bacteria. They are enclosed in secretion and are always found in the same position inside the receptaculum.

Complex genital system of a haplogyne spider (Arachnida, Araneae, Tetrablemmidae) indicates internal fertilization and full female control over transferred sperm

The female genital organs of the tetrablemmid Indicoblemma lannaianum are astonishingly complex. The copulatory orifice lies anterior to the opening of the uterus externus and leads into a narrow insertion duct that ends in a genital cavity. The genital cavity continues laterally in paired tube-like copulatory ducts, which lead into paired, large, sac-like receptacula. Each receptaculum has a sclerotized pore plate with associated gland cells. Paired small fertilization ducts originate in the receptacula and take their curved course inside the copulatory ducts. The fertilization ducts end in slit-like openings in the sclerotized posterior walls of the copulatory ducts. Huge masses of secretions forming large balls are detectable in the female receptacula. An important function of these secretory balls seems to be the encapsulation of spermatozoa in discrete packages in order to avoid the mixing of sperm from different males. In this way, sperm competition may be completely prevented or at least severely limited. Females seem to have full control over transferred sperm and be able to express preference for spermatozoa of certain males. The lumen of the sperm containing secretory balls is connected with the fertilization duct. Activated spermatozoa are only found in the uterus internus of females, which is an indication of internal fertilization. The sperm cells in the uterus internus are characterized by an extensive cytoplasm and an elongated, cone-shaped nucleus. The male genital system of I. lannaianum consists of thick testes and thin convoluted vasa deferentia that open into the wide ductus ejaculatorius. The voluminous globular palpal bulb is filled with seminal fluid consisting of a globular secretion in which only a few spermatozoa are embedded. The spermatozoa are encapsulated by a sheath produced in the genital system. The secretions in females may at least partly consist of male secretions that could be involved in the building of the secretory balls or play a role in sperm activation. The male secretions could also afford nutriments to the spermatozoa.

Grey-matter abnormalities in boys with Tourette syndrome: magnetic resonance imaging study using optimised voxel-based morphometry

The genesis of Tourette syndrome is still unknown, but a core role for the pathways of cortico-striatal-thalamic-cortical circuitry (CSTC) is supposed. Volume-rendering magnetic resonance imaging data-sets were analysed in 14 boys with Tourette syndrome and 15 age-matched controls using optimised voxel-based morphometry. Locally increased grey-matter volumes (corrected P < 0.001) were found bilaterally in the ventral putamen. Regional decreases in grey matter were observed in the left hippocampal gyrus. This unbiased analysis confirmed an association between striatal abnormalities and Tourette syndrome, and the hippocampal volume alterations indicate an involvement of temporolimbic pathways of the CSTC in the syndrome.