Identification of Genetic Variants of Human Papillomavirus in a Group of Mexican HIV/AIDS Patients and Their Possible Association with Cervical Cancer

Infections caused by the human immunodeficiency virus (HIV) and human papillomavirus (HPV) cause thousands of deaths worldwide each year. So far, there has been no consensus on whether there is a direct relationship between the incidence of neoplasms and the immunosuppression caused by HIV that could help understand if coinfection increases the likelihood of cervical cancer. The objective of the study was to identify the presence of genetic variants of HPV in a group of HIV-positive women and their possible association with cervical cancer. Cervical samples were taken from HIV-positive patients for cytological analysis to identify the HPV genotype by polymerase chain reaction (PCR) and sequencing. The most prevalent L1 capsid protein mutations in the HPV genotype were analyzed in silico. Various types of HPV were identified, both high-risk (HR) and low-risk (LR). The most prevalent genotype was HPV51. Analysis of the L1 gene sequences of HPV51 isolates showed nucleotide variations. Of the samples analyzed in Puebla, Mexico, HPV51 had the highest incidence (17.5%, 7/40). Different mutations, which could be used as population markers, were detected in this area, and they have not been reported in the L1 databases for HPV51 in Mexico. Genotypes 6, 14, 86, 87, 89, and 91, not detected or reported in samples from patients with HPV in Mexico, were also identified. Data from the population analyzed suggest no direct relationship between HIV immunosuppression and cervical cancer, regardless of the high- or low-risk HPV genotype. Furthermore, it is possible to develop regional population markers for the detection of HPV based on the mutations that occur in the sequence of nucleotides analyzed.     

Properties and Possible Physiological Significance of Cell Wall Calcium Binding in Etiolated Pea Epicotyls

Baydoun, E. A-H. and Brett, C. T. 1988. Properties and possiblephysiological significance of cell wall calcium binding in etiolatedpea epicotyls.—J. exp. Bot. 39: 199–208. The binding of ⁴⁵Ca²⁺ ions to cell walls prepared from pea epicotylswas examined in young and old parts of the epicotyl, and wasfound to be considerably greater, on a carbohydrate basis, inthe older, non-growing cells. A similar comparison between light-and dark-grown stems showed greater binding in the dark-grownstems. The polygalacturonase-insensitive component of the bindingcontained at least three types of binding with different affinities,and had an apparent pK of 4.3. The specificity of the bindingfor calcium ions was examined and a considerable degree of specificitywas observed. The specificity of inhibition by calcium of epicotylelongation was similar to the specificity of calcium binding.A specific calcium chelator, EGTA, when present at a concentrationof above 10 mol m^–3, promoted the extension of matureregions of the epicotyl, while inhibiting extension of youngertissue. Key words: Cell wall, calcium, pea epicotyl     

Fine structural basis of the cutaneous water barrier in nestling Zebra Finches Poephila guttata

Transepidermal water loss was studied in nestlings, fledglings and adults of the xerophylic Zebra Finch Poephila guttata. Nestlings lose little water (2–4 ppm/0–5 cm²/h) through the skin as compared to adults (60–70 ppm/0–5 cm²/h). Light and electron microscopic examination of the skin sections of both age classes revealed an abundance of lipids in the form of vacuoles and large multigranular bodies in the epidermis of nestlings, but few such lipid bodies in the epidermis of adults. Some of the disc-like contents of granular bodies appear to be extruded into the intercellular spaces. Based on earlier studies with mammals and reptiles, it is concluded that epidermal lipids are the basis of the integumentary permeability barrier in nestlings.     

A signal-substrate match in the substrate-borne component of a multimodal courtship display

The environment can impose strong limitations on the efficacy of signal transmission. In particular, for vibratory communication, the signaling environment is often extremely heterogeneous at small scales. Nevertheless, natural selection is expected to select for signals well-suited for effective transmission. Here, we test for substrate-dependent signal efficacy in the wolf spider Schizocosa stridulans Stratton 1991. We first explore the transmission characteristics of this important signaling mo-dality by playing recorded substrate-bome signals through three different substrates (leaf Utter, pine litter, and red clay) and measuring the propagated signal. We found that the substrate-borne signal of S stridulans attenuates the least on leaf litter, the substrate upon which the species is naturally found. Next, by assessing mating success with artificially muted and non-muted males across different signaling substrates (leaf litter, pine litter, and sand), we explored the relationship between substrate-bome signaling and signaling substrate for mating success. We found that muted males were unsuccessful in obtaining copulations re-gardless of substrate, while mating success was dependent on the signaling substrate for non-muted males. For non-muted males, more males copulated on leaf litter than any other substrate. Taken together, these results confirm the importance of sub-strate-borne signaling in & stridulans and suggest a match between signal properties and signal efficacy - leaf litter transmits the signal most effectively and males are most successful in obtaining copulations on leaf litter.     

A yellow–green algal symbiont in the freshwater sponge, Corvomeyenia everetti: convergent evolution of symbiotic associations

1. A previously undescribed symbiotic relationship is reported between the freshwater sponge Corvomeyenia everetti , which occurs throughout eastern North America, and a yellow-green alga.
2. Ultrastructural and pigment analyses place the algal endosymbiont within the class Eustigmatophyceae in the division Heterokontophyta.
3. The relationship of the alga with C. everetti appears to be specific and it contributes significantly to the energy budget of the host.
4. Although the growth form of C. everetti is very similar to other freshwater sponges that usually have green-algal symbionts, its phylogeny has been proposed to be quite distinct, suggesting convergent evolution by both algae and sponges in the development of symbiotic associations in fresh water.     

Studies on Ectomycorrhizae of Pine II. Growth Inhibition of Mycorrhizal Fungi by Volatile Organic Constituents of Pinus silvestris (Scots Pine) Roots

The effects of several monoterpenes and the sesquiterpene longifolene on the vegetative growth of two mycorrhizal fungi, Boletus variegatus and Rhizopogon roseolus, were studied in petri plate experiments on an agar medium. The test substances are natural constituents of Pinus silvestris (Scots pine) roots. Vapors from 20 μl of all the test substances, upon a 5 day exposure inhibited the growth of both the mycorrhizal fungi 55% to 86%. The two fungi, however, differed in their tolerance to individual compounds. It is suggested that the terpenes and the sesquiterpenes play an important role in the development of the symbiotic condition in ectomycorrhizae by restricting the growth of the mycorrhizal fungi within the host root.