Female control of paternity

Of the two components of sexual selection, female choice is much less obvious than male-male competition, and hence has always been considered to be of secondary importance. However, recent field observations and new theory have brought about a radical change of emphasis. It now appears that although a female's choice of who fathers her offspring often occurs in a subtle manner, it may be widespread and take place through a variety of behavioural and physiological mechanisms, including the manipulation of male behaviour and the selection of sperm within the female reproductive tract.     

Molecular evaluation of an Alu repeat including a polymorphic variable poly(dA) (AluVpA) in the vitamin D binding protein (DBP) gene

We investigated an Alu element at the end of intron 8 of the human vitamin D-binding protein (hDBP, group-specific component, GC) gene that shows a polymorphic poly(A) tail due to a variable number of tandem repeats (AluVpA) forming the 3 end of this member of the most abundant class of short interspersed repeated DNA element (SINES). The Alu element sequence in intron 8 of the GC gene was identical in all three common GC alleles (GC*1F, GC*1S, and GC*2) and could be classified as an Alu-Sa or Alu class-II sequence. The polymerase chain reaction was used to amplify selectively a fragment of about 200 bp containing the identified (TAAA)n repeat from genomic DNA of 188 unrelated human subjects. The size of the amplified products was determined by polyacrylamide gel electrophoresis. Four alleles (named GC-18*6, GC-I8*8, GC-I8*10, and GC-18*11) were found that differed in size by multiples of four nucleotides. The allele frequencies ranged from 0.0053 to 0.8511 and the observed heterozygosity was 26%. The stable inheritance of this polymorphic patterned poly(A) sequence was confirmed by a segregation study of a highly informative family with 19 members. Statistically significant linkage disequilibrium between the AluVpA and the GC isoelectric focusing (IEF) phenotypes was found in a sample of 188 unrelated individuals and delta values were calculated from the observed haplotype distribution.     

Screening for point mutations in exon 10 of the low density lipoprotein receptor gene by analysis of single-strand conformation polymorphisms: detection of a nonsense mutation — FH469→Stop

DNA from 40 unrelated familial hypercholesterolemia (FH) heterozygotes were subjected to analyses of single-strand conformation polymorphisms (SSCPs) of exon 10 of the low density lipoprotein receptor (LDLR) gene. Four different SSCP patterns were observed. The underlying mutations were characterized by DNA sequencing. Three of the patterns represented the three genotypes of a recently described sense mutation in codon 450. A method based upon the polymerase chain reaction (PCR) was developed to analyze this mutation. The frequencies of the wild-type (G at nucleotide 1413) and mutant (A at nucleotide 1413) alleles were 0.56 and 0.44, respectively. The fourth pattern was found in only one FH heterozygote and was caused by heterozygosity at nucleotide 1469 (G/A). Nucleotide 1469 is the second base of codon 469_Trp(TGG). The GA mutation changes this codon into the amber stop codon, and is referred to as FH_469Stop. The mutant receptor consists of the amino terminal 468 amino acids. Because the truncated receptor has lost the membrane-spanning domain, it will not be anchored in the cell membrane. FH_469Stop destroys an AvaII restriction site, and this characteristic was used to develop a PCR method to establish its frequency in Norwegian FH subjects. Two out of 204 (1%) unrelated FH heterozygotes possessed the mutation.     

Life cycle of the microbivorous Antarctic Dry Valley nematode Scottnema lindsayae (Timm 1971)

The life cycle of the Antarctic Dry Valley soil nematode, Scottnema lindsayae (Timm 1971) was studied in laboratory culture at two temperatures, 10°C and 15°C. Soil yeast and bacteria isolated with the nematodes were used as the food source. The species reproduced sexually. The higher temperature had a negative effect on the life cycle. The number of eggs per female and the number of juveniles developing per female were greater at 10°C than at 15°C. Juveniles developed faster at 10°C and four juvenile stages were observed outside of the egg at both temperatures. The unusually long life cycle (218 d at 10°C) suggests that more than one austral summer may be required for successful completion. An increase in Dry Valley soil temperatures associated with potential global environmental change may have detrimental effects on soil nematodes.     

Improved pulse sequences for measuring coupling constants in 13C, 15N-labeled proteins

Summary NMR pulse sequences for measuring coupling constants in ¹³C, ¹⁵N-labeled proteins are presented. These pulse sequences represent improvements over earlier experiments with respect to resolution and number of radiofrequency pulses. The experiments are useful for measuring J_NH , J_NCO, J_NC , J_H ^N _CO and J_H ^N _H . Applications to chymotrypsin inhibitor 2 (CI-2) are shown.     

Do NOE distances contain enough information to assess the relative populations of multi-conformer structures?

Summary The feasibility of determining the relative populations of multi-conformer structures from NOE-derived distances alone is assessed. Without cross-validation of the NOE restraints, any population ratio can be refined to a similar quality of the fit. Complete cross-validation provides a less biased measure of fit and allows the estimation of the correct population ratio when used in conjunction with very tight distance restraints. With the qualitative distance restraints most commonly used in NMR structure determination, cross-validation is unsuccessful in providing the correct answer. Other experimental sources are therefore needed to determine relative populations of multi-conformer structures.To whom correspondence should be addressed.     

Ultrastruktur und Differenzierung der prostatoiden Organe von Polystyliphora filum (Plathelminthes,Proseriata)

Zusammenfassung Polystyliphora filum besitzt neben einem dem männlichen Begattungsorgan angeschlossenen Stilett eine Vielzahl gleichartiger prostatoider Organe, stets caudal des Begattungsorgans serial angeordnet. Jedes dieser prostatoiden Organe besteht aus einem Stilett, das in ein Atrium reicht, und einem caudal anschließenden Bulbus. Das Stilett hat die Form eines gebogenen Trichterrohres mit einem plattenförmigen Fortsatz in der Mitte; Trichterrohr und Fortsatz werden zusammen in einer einzelnen Zelle ausdifferenziert. In einer frühen Bildungsphase wird in der basalen Hälfte zunächst ein Gerüst aus Mikrotubuli angelegt, an das sich elektronendichtes Material anlagert. In einem späteren Bildungsstadium werden teilweise die Zwischenräume zwischen der entstehenden Hartstruktur und der Außenmembran der Bildungszelle mit elektronendichtem Material ausgefüllt. Die Spitze des Stiletts wird durch Anlagerung elektronendichten Materials an die Außenmembran gebildet. Die Differenzierung der gesamten Hartstruktur erfolgt simultan und intrazellulär. Gleichzeitig wird auch die gesamte Muskulatur des prostatoiden Organs ausgebildet. Die vollständig ausdifferenzierten prostatoiden Organe enthalten keine Spermien, sondern nur große Mengen eines grobscholligen Sekretes.

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Ultrastructure and differentiation of the prostatoid organs of Polystyliphora filum (Plathelminthes, Proseriata)

Summary In addition to a male copulatory organ containing a stylet, Polystyliphora filum has numerous uniform prostatoid organs which are arranged in series caudally to the copulatory organ. Each of these prostatoid organs consists of a stylet, extending into an atrium, and caudal to this a bulb. The stylet is funnel-shaped with a curved distal part and a flattened projection in the middle; funnel and projection are differentiated together in a single cell. In an early phase of differentiation, a framework of microtubules is built in the basal part, and this becomes enveloped by electron-dense material. In a later phase, the space between the formed hard structure and the outer membrane of the style building cell is partially filled up with electrondense material. The distal part of the stylet if formed by electron-dense material taken up to the outer membrane. The whole hard structure is differentiated simultaneously and intracellularly. At the same time the whole muscular system of the prostatoid organ is formed. The completed prostatoid organs do not contain sperm, but much coarsegrained medium electron-dense secretion.

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Abkürzungen am Atriummuskulatur - bl Basallamina - bm Bulbusmuskulatur - bmk Kernregion einer Bulbusmuskelzelle - bz Stilettbildungszelle - cw Cilienwurzel - ep Epidermis - fz Füllzelle - hz Hüllzelle - mv Mikrovilli - n Nerv - p Protraktor - pa Protraktoransatz - r ciliärer Rezeptor - s Stilett - sd Septatdesmosomen - sm Schließmuskel - sz Sekretzelleg     

Vascular permeability to proteins and peptides in the mouse pineal gland

Summary The permeability of fenestrated capillaries in the mouse pineal gland to proteins and peptides was demonstrated by means of ultrastructural tracers. Horseradish peroxidase (HRP) and microperoxidase (MP) were injected intravenously and allowed to circulate for approximately 30 s, 1 min, 5 min, 1 or 2h. The tissue was then fixed by vascular perfusion or by immersion with aldehydes. In all experiments a pronounced extravasation of HRP and MP occurred. Transendothelial vesicular transport seemed to have occurred across the fenestrated capillaries. The most pronounced tracer labeling of vesicles was found after 1 min of MP- or HRP-circulation. The vesicles were uncoated and more than 70 % of the HRP-and MP-containing vesicles exhibited diameters between 50 and 110 nm. Furthermore, three other transcapillary pathways taken by the tracers are suggested: 1) via intercellular junctions, 2) through fenestrae and 3) via channels formed by fusion of vesicles with the luminal and abluminal cell membranes. Based on these results, it is assumed that the capillaries in the mouse pineal gland are also permeable to peptides synthesized and secreted by the pineal gland.Part of this study was presented at the EMCELL-76 meeting, Copenhagen, 1976