The dorsal column system: I. Existence of long ascending postsynaptic fibres in the cat's fasciculus gracilis

Summary Microelectrode recordings were made from dorsal column fibres at the 12th thoracic segment in cats. Two kinds of activity were elicited by electric shocks applied on the sciatic nerve in the popliteal fossa: primary afferent activity and trans-synaptically evoked activity. The dorsal column postsynaptic (DCPS) fibres represented 9.3% of the total population of fibres studied in the fasciculus gracilis and 14.5% of those with receptors in the skin. They were found to lie between the primary fibres of cutaneous and those of deep origin. The fastest fibres of the alpha range contributed to their activation and it is likely that C fibres contributed as well. 87% of the DCPS fibres studied at Th 12 were antidromically activated from the first cervical segment, and their conduction velocities measured between cervical and thoracic levels ranged from 16 to 71 m/sec.     

Periovulatory increase in temperature difference within the rabbit oviduct

BACKGROUND: Earlier studies demonstrated a small temperature difference between the sperm storage and fertilization sites within the oviducts of rabbits and pigs. Our aim was to reveal the time dependence of this temperature difference relative to ovulation, and to determine how this difference is generated-by temperature elevation at one of these sites or by temperature decrease at the other site. METHODS: The temperature at the sperm storage site (at the isthmus near the uterotubal junction) and at the fertilization site (the isthmic-ampullary junction) of rabbit oviducts were measured before, during, and after ovulation by two probes, connected to digital thermometers. Rectal temperature was constantly measured and served as a control for body temperature. RESULTS: The temperature difference between the fertilization site and the storage site was 0.8+/-0.2 degrees C before ovulation. This difference increased at ovulation, reaching 1.6+/-0.1 degrees C after ovulation (P<0.03). This increased difference was mainly due to temperature decrease in the sperm storage site. CONCLUSION: The temperature-difference increase within the rabbit oviduct is generated at ovulation by a reduced temperature at the sperm storage site. This temperature gradient may play a role in mammalian reproduction via sperm thermotaxis.     

Role of volume-stimulated osmolyte and anion channels in volume regulation by mammalian sperm

The ability to maintain cellular volume is an important general physiological function. Swelling induced by hypotonic stress results in the opening of channels, through which ions exit with accompanying water loss (regulatory volume decrease, RVD). RVD has been shown to occur in mammalian sperm, primarily through the opening of quinine-sensitive potassium channels. However, as yet, direct evidence for the participation of anion channels in sperm RVD has been lacking. The chloride channel type ClC-3 is believed to be involved in RVD in other cell types. Using electronic cell sizing for cell volume measurement, the following results were obtained. (i) The anion channel blockers 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), tamoxifen and 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS) increased hypotonic swelling in concentration-dependent fashion, whereas verapamil (P-glycoprotein inhibitor) had little effect. The most potent, NPPB and DIDS, blocked RVD without affecting cell membrane integrity at effective concentrations. (ii) When gramicidin was included to dissipate Na+/K+ gradients, major secondary swelling was observed under hypotonic conditions. This secondary swelling could be reduced by NPPB, and suppressed completely by replacing chloride in the medium with sulphate, an ion which does not pass through chloride channels. It was deduced that the initial hypotonic swelling activated an anion channel through which chloride ions could then enter freely down a concentration gradient, owing to the lack of a counter-gradient of potassium. (iii) Taurine, an osmolyte often involved in RVD, does not appear to play a role in sperm RVD because lengthy preincubation with taurine did not alter sperm RVD response. Our observations provide direct evidence that a chloride channel (possibly ClC-3) is involved in the process of volume regulation in mammalian sperm.     

Reduced nocturnal morphine analgesia in mice following a geomagnetic disturbance

Latency to respond to an aversive thermal stimulus and the degree of analgesia induced by morphine were examined in mice injected with either isotonic saline or morphine sulfate (10 mg/kg) during midscotophase of a 12:12 h LD cycle. When mean response latencies were compared to the degree of geomagnetic disturbance (Ap index) present on test days, it was found that during the geomagnetic storm on December 17th, 1982, a significant reduction (P<0.01) in response latency was evident in both saline- and morphine-treated mice. The reduction in response latencies was greater, and lasted longer in the morphine-treated animals. It is suggested that the pineal gland may mediate this biomagnetic effect.     

Craniosynostosis in Twist heterozygous mice: A model for Saethre‐Chotzen syndrome

Saethre‐Chotzen syndrome is a common autosomal dominant form of craniosynostosis, the premature fusion of the sutures of the calvarial bones of the skull. Most Saethre‐Chotzen syndrome cases are caused by haploinsufficiency for the TWIST gene. Mice heterozygous for a null mutation of the Twist gene replicate certain features of Saethre‐Chotzen syndrome, but have not been reported to exhibit craniosynostosis. We demonstrate that Twist heterozygous mice exhibit fusions of the coronal suture and other cranial suture abnormalities, indicating that Twist heterozygous mice constitute a better animal model for Saethre‐Chotzen syndrome than was previously appreciated. Anat Rec 268:90–92, 2002. © 2002 Wiley‐Liss, Inc.     

Anonymous or identity-registered sperm donors? A study of Dutch recipients' choices

BACKGROUND: The aim of the present study was to gain insight into parents' own donor preferences within a system offering the choice between an anonymous and identity-registered donor. A comparison was made between recipients choosing for an anonymous donor (AD choosers) and those choosing for an identifiable donor (ID choosers) with regard to their sexual orientation, demographic characteristics, disclosure issues and infertility distress. METHODS: Data from 105 couples (61% heterosexual, 39% lesbian) were registered on a standardized form during implication counselling sessions previous to treatment. RESULTS: Sixty-three per cent of the heterosexual couples and 98% of the lesbian couples had chosen an ID donor. Major differences between ID and AD choosers were identified. Among the ID choosers secrecy towards the child was no option, whereas 83% of the AD choosers did not intend to inform their child. Compared with heterosexual ID choosers, AD choosers were more distressed about their infertility and had a lower educational level. CONCLUSION: Legislation imposing ID donors appears to be acceptable for the majority of this study population. For a vulnerable group of heterosexual couples, who remained secretive about the use of a donor, adaptation to the new system is not self-evident.     

Muscle-epidermis interactions affect exoskeleton patterning in Caenorhabditis elegans.

The C. elegans hypodermis is a single epithelial cell layer separated from the musculature by a thin basement membrane on its basal surface. The hypodermis secretes the extracellular material of the cuticle from its apical surface. The regulation of cuticle synthesis and apical secretion is not well understood. UNC-95 is a component of the muscle dense bodies and M-lines, which are integrin-based adhesion complexes required for force transduction to the cuticle. Using gene expression profiling and in vivo assays, we show that, in unc-95 mutant worms, there is an increase in expression levels of a group of hypodermal and pharyngeal genes related to cuticle structure and molting. Moreover, the cuticle structure of unc-95 mutant adult is impaired. Our findings suggest that aberrant force transduction from the structurally impaired muscle attachments across the basement membrane to the underlying hypodermis elicits intercellular signaling that plays a role in regulating cuticle synthesis and patterning.     

Semi-automated analysis of manually reconstructed tracks of progressively motile human spermatozoa

Several alternative algorithms for computer-assisted derivationof measurements of movement characteristics from manually reconstructedtracks of progressively motile human spermatozoa were compared.Fifty tracks were reconstructed at 30 Hz from video recordingsand analysed using traditional manual methods and by four combinationsof computer algo rithms. The best algorithm set was identified(‘Video-mot.mdpt’) and the values for the curvilinear,average path and linear velocities (V_CVL, V_AVE and V_LIN respectively),the amplitude of lateral displacement of the sperm head aboutthe axis of progression (A_H) and the number of times the spermhead crossed the average path (the ‘beat/cross frequency’,BXF) obtained using it were compared to those obtained by manualanalysis. There was a considerable time saving when the computer-assistedmethod was used and the values it gave for the various movementcharacteristics showed good correspondence with those obtainedmanually. In addition, repeated data entry and analysis wasfound to be highly reproducible. When the tracks were re-plottedat 6 Hz (as used by the multiple-exposure photomicrography methodfor sperm motility analysis) insufficient information remainedin the tracks for reliable determination of anything other thanV_LIN We conclude that the Videomot.mdpt program provides reliablevalues for the movement characteristics of progressively motilehuman spermatozoa, and believe it will be of great value inthe validation of commercial systems providing automated spermmovement analysis and in laboratories which do not have accessto such costly equipment.     

Frequent polymorphism of the mitochondrial DNA polymerase gamma gene (POLG) in patients with normal spermiograms and unexplained subfertility

BACKGROUND: Male fertility largely depends on the quality of sperm production, which may be affected by environmental and genetic factors. In this study, we explored a possible role of the polymerase gamma (POLG) gene polymorphism, recently reported to be associated with male infertility in some populations. METHODS: The polymorphic CAG repeat (usually 10 codons long) in the POLG gene was studied in 1298 male subjects: 429 patients with infertility/subfertility, and 869 controls (495 men from the general population with unknown fertility and 374 recent fathers). In all subjects, the POLG polymorphism was assessed in relation to their semen quality, and--in the fertile controls--with biological fecundity measured as waiting time-to-pregnancy (TTP) for the couples. In the patients lacking the common POLG allele, the outcome of the assisted reproductive techniques (ART) for the couples was evaluated. RESULTS: The absence of one (10/ not equal to 10) or both common POLG alleles (not equal to 10/not equal to 10) was more frequent among the subfertile patients than among fertile controls (P=0.021 and P=0.04 respectively). The estimated predictive value for infertility in a man homozygous for the POLG polymorphism was 15.5% (95% CI: 4.8-51%). There was a positive association with sperm concentration: 14.3% of the normospermic subfertile patients were homozygous for the absence of the common POLG allele (not equal to 10/not equal to 10), in comparison with 2.3% of unselected controls (P=0.001) and 0.9% of the fertile men (P=0.0001). No association with sperm motility, morphology and TTP was found. Spermatozoa of the three not equal to 10/not equal to 10 patients treated with IVF retained the ability to penetrate the egg, but the fertilization rate was low. Nine homozygous not equal to 10/ not equal to 10 patients were treated with ICSI, resulting in pregnancy in seven couples. CONCLUSIONS: The POLG gene polymorphism should be considered as a possible contributing factor in patients with unexplained subfertility and normal spermiograms. The oocyte penetration ability of sperm may be partially impaired in the not equal to 10/not equal to 10 patients but most of them can be successfully treated with ICSI.