Permineralized seed fern cupules from the Triassic of Antarctica: implications for cupule and carpel evolution

In this paper we describe the first anatomically preserved Mesozoic seed fern cupule–Petriellaea. The multiovulate cupules were produced singly at the end of a short dichotomizing axis. Cupules are bilateral with a dorsal groove and transverse narrow ventral opening. The vascular system of the cupule consists of a series of traces that extend up the dorsal surface of the cupule and down the ventral face. Ovules are orthotropus, sessile, and borne on the adaxial surface of the leaflike cupule either singly or in multiple rows. They are up to 1.5 mm long, triangular in transverse section, and characterized by a multilayered integument. Nucellus and integument are fused throughout their length, but no pollen chamber is present. In the chalaza is a small vascular disc of transfusion tracheids that represents the extent of the ovule vascular system. Ovules are interpreted as being fossilized at a prepollination stage, although a few possess some evidence of a cellularized megagametophyte. These permineralized cupules indicate that in at least one Mesozoic seed fern group, ovule enclosure resulted from the transverse folding (tip to petiole) of a megasporophyll bearing adaxial ovules. Cupule morphology and ovule enclosure in other Late Paleozoic and Mesozoic seed ferns is discussed.     

Superovulatory response of ovarian follicles of Wave 1 versus Wave 2 in heifers

Experiments were designed to test the hypotheses that ovarian follicular response to superstimulatory treatment initiated during Wave 1 is equivalent to that of Wave 2, and recovery rate and quality of ova embryos derived from follicles of Wave 1 are equivalent to those derived from follicles of Wave 2. In a preliminary experiment (Experiment 1), heifers were given Folltropin-V (20 mg NIH-FSH-P1, im, bid for 5 d) beginning the day after emergence of the first (n=10) or second (n=10) follicular wave of the estrous cycle, equivalent to approximately Day 1 and Day 10, respectively (Day 0=ovulation). Luteolysis was induced with cloprostenol (500 mug im, bid) on the fourth day of treatment. Fewer (P<0.05) ovulations per heifer were induced in the Wave 1 group than in the Wave 2 group (4.6+/-1.0 vs 9.1+/-1.3). However, the interval from wave emergence to initiation of treatment was found, in retrospect, to have been longer (P<0.05) in the Wave 1 group, i.e., treatment was initiated relatively later with respect to wave emergence. Experiment 2 was designed to correct this disparity and to initiate the same treatment protocol on the day of wave emergence rather than the day after (n=21 per Wave group). There was no difference between Wave 1 and Wave 2 groups in the interval from wave emergence to initiation of treatment (0.4+/-0.1 d), the number of ovulations detected by ultrasonography (6.6+/-1.0 vs 8.2+/-1.7), the number of CL detected at slaughter (6.5+/-0.9 vs 8.1+/-1.8), the total number of ova embryos recovered (5.2+/-0.7 vs 5.1+/-0.8), or the number of fertilized embryos collected (2.8+/-0.6 vs 3.0+/-0.6). In addition, there was no difference between groups in the proportion of heifers that ovulated in either experiment; collectively, luteolysis and ovulation was induced in 58 of 60 heifers. The results supported the general hypothesis that follicles and oocytes of the first and second follicular waves are equivalent in the response to superstimulatory treatment. Regardless of which follicular wave, initiation of treatment near the time of wave emergence appears critical for maximal superovulatory response. Because of the consistency in the time of emergence of Wave 1 (day of ovulation) and equivalence in superovulatory response, use of Wave 1 rather than subsequent follicular waves may be more convenient and time-sparing in superovulation programs; the day of estrus (day before ovulation) may be used as a consistent point of reference for the start of treatment.     

A refined restriction map of YAC clones spanning the entire human dystrophin gene

The enormous size of the human dystrophin gene (2300 kb) has so far hindered the analysis of its organization and the characterization at the genomic level of the deletion and duplication mutations causing Duchenne or Becker muscular dystrophy. A detailed physical map of the gene locus would considerably simplify these studies. We constructed a refined, long-range restriction map of the entire human dystrophin gene, using 12 overlapping YAC clones as DNA sources. The sites for six rare cutting enzymes (SfiI, NruI, EagI, BssHII, SacII, and NotI) were mapped by partial digest analysis of YACs over a region of 2600 kb, within a level of resolution of about 10 kb. Such a map provides the first detailed representation of the physical structure of the dystrophin gene. It will be useful for mapping unlocalized exons and, eventually, for the characterization of deletions and duplications leading to disease.     

Cross-Reactive Antigens Between Pea and Some Fungal Plant Pathogens

Antiserum to pea was used to analyse cross-reactive antigens (CRA) between pea and some fungal plant pathogens with different levels of specificity towards this host by using both double diffusion and immunoblotting techniques. Non pathogens of pea were also included in the study. Nectria haematococca MPVI, the three formae speciales dianthi, lycopersici and pisi of Fusarium oxysporum and Ascochyta pisi produced strong reactions with both techniques. In N. haematococca MPI, F. solani f. sp. phaseoli, V. dahliae and Phoma medicaginis var. pinodella instead, reactions were not detected by double diffusion but only the more sensitive immunoblotting technique. No CRA were observedin, the non-specific pathogens Rhizoctonia solani, Sclerotium rolfsii and Sclerotinia sclerotiorum, as well as in the non-pathogen Phytophthora capsici. The immunoblotting patterns of the most reactive fungi showed common bands with molecular weights of 84, 75 and 62 kDa. Some bands were present only in the specific pathogens N. haematococca MPVI and F. oxysporum f.sp. pisi. The possible involvement in host-parasite interactions of cross-reactive antigens which are, present in the analyzed fungi is discussed.     

Species richness and endemism of birds in Bioko

The status of 50 taxonomically unique bird taxa found in Bioko is described. A complete updated species list for birds in Bioko is also given. Notes on habitat occupied and altitudinal distribution of each species as well as information on their general abundance is also included. Species distributions may have been affected by habitat modifications brought about by humans but most taxonomically unique forms are found in the montane areas. Comparisons are made with the neighbouring Mount Cameroon area.     

Comparative analysis of multiple protein-sequence alignment methods [published erratum appears in Mol Biol Evol 1994 Sep;11(5):811]

We have analyzed a total of 12 different global and local multiple protein-sequence alignment methods. The purpose of this study is to evaluate each method's ability to correctly identify the ordered series of motifs found among all members of a given protein family. Four phylogenetically distributed sets of sequences from the hemoglobin, kinase, aspartic acid protease, and ribonuclease H protein families were used to test the methods. The performance of all 12 methods was affected by (1) the number of sequences in the test sets, (2) the degree of similarity among the sequences, and (3) the number of indels required to produce a multiple alignment. Global methods generally performed better than local methods in the detection of motif patterns.      

On the use of the quenching of luminol luminescence to evaluate sod activity

Addition of horseradish peroxidase to a luminol solution (pH = 9.4) produces a burst of light followed by a steady luminescence that lasts for several minutes. This steady-state luminescence is readily quenched by SOD, with a concentration (the additive concentration needed to decrease by one-half the emitted luminescence intensity) of c.a. 4 ng/ml (14 mU/ml). The luminescence intensity decrease can then be employed to evaluate SOD activity in SOD-containing samples. However, the light intensity can also be quenched by additives, such as Trolox, that are able to trap luminol-derived intermediates. It is proposed that double quenching experiments must be performed in order to be able to relate the observed effect of an additive to its SOD-like activity.     

Distribution of microtubules during the growth of tobacco pollen tubes

Summary— The distribution of microtubules was investigated in Nicotiana tabacum pollen tubes at different stages of tube growth by immunofluorescence microscopy. Using specific antibodies, the presence of microtubules consisting of different tubulin isoforms was tested. α-, β- and tyrosinated α-tubulin were present within the tube, whereas the acetylated form was lacking. The presence of tubulin subunits in pollen tube extracts was also investigated by immunoblotting analyses. The use of a confocal laser scanning microscope integrated with computer-assisted imaging, allowed a detailed visualization of the microtubule distribution and organization. Cytoplasmic microtubules organized as short bundles with various orientations were detected at the apex of long tubes.     

Environmental tracking by females

Human females are generally reserved in their sexuality, in keeping with their heavy investment in reproduction. Males tend to be less reserved. Relative to males, however, females demonstrate more variability in sexuality and are more likely to inhibit or express high levels of sexuality. The heightened variability may in part originate with genetic mechanisms that predispose females toward greater variability (the Lyon hypothesis). Menarche, menstrual cycles, menopause, food reactions, responses to living conditions, reactions to cultural factors, and responses to sexual stimuli and potential mates are unique to or are more variable among females than males. There is a correlation between the variation expressed and female reproductive potential—females tend to shift dramatically from sexual inhibition to sexual expression. Females apparently track the quality of the environment and link their sexuality to reproductive opportunities. Successful male reproduction depends less on quality environments and more on the availability of females. In short, females track the environment; males track the females.