An acoustic tracking of a megamouth shark, Megachasma pelagios: a crepuscular vertical migrator

A 4.9 m TL megamouth shark, only the sixth specimen known to science, was tracked continuously for 50.5 h, during which it exhibited distinct vertical migrations at the dawn and dusk transitions. The male shark was captured on 21 October 1990 in a drift gill net off Dana Point, California, restrained overnight in a harbor, and released at sea the next afternoon. Horizontally, the shark moved slowly southward, covering 62 km on a relatively straight path with no significant diel changes. For the major part of the tracking, its rate of movement was 1.15 km h^–1, as determined from positions at 15 min intervals. Considering a probable head current of 10–25 cm sec^–1, its estimated through-the-water swimming speed was more likely 1.5–2.1 km h^–1 (X¯ = 1.8, representing 0.1 body lengths sec^–1). Vertically, the shark stayed shallow at night (12–25 m depth range, X¯ = 17) and deep during the days (120–166 m, X¯ = 149) but still well above the bottom at 700–850 m. The four twilight depth-change events were very distinct and always spanned the times of sunset or sunrise. The ascent and descent profiles are a reasonble match to isolumes on the order of 0.4 lux for an extinction coefficient (0.07) calculated from water transparency measurements. Furthermore, the steepest parts of the shark's profiles correspond closely to the times of maximum rate-of-change of illumination. These findings suggest that, except during nights, the shark's chosen depth was to a large degree determined by light level.     

Statistical methods for estimating doubling time in in vitro cell growth

Summary Doubling time has been widely used to represent the growth pattern of cells. A traditional method for finding the doubling time is to apply gray-scaled cells, where the logarithmic transformed scale is used. As an alternative statistical method, the log-linear model was recently proposed, for which actual cell numbers are used instead of the transformed gray-scaled cells. In this paper, I extend the log-linear model and propose the extended log-linear model. This model is designed for extra-Poisson variation, where the log-linear model produces the less appropriate estimate of the doubling time. Moreover, I compare statistical properties of the gray-scaled method, the log-linear model, and the extended log-linear model. For this purpose, I perform a Monte Carlo simulation study with three data-generating models: the additive error model, the multiplicative error model, and the overdispersed Poisson model. From the simulation study, I found that the gray-scaled method highly depends on the normality assumption of the gray-scaled cells; hence, this method is appropriate when the error model is multiplicative with the log-normally distributed errors. However, it is less efficient for other types of error distributions, especially when the error model is additive or the errors follow the Poisson distribution. The estimated standard error for the doubling time is not accurate in this case. The log-linear model was found to be efficient when the errors follow the Poisson distribution or nearly Poisson distribution. The efficiency of the log-linear model was decreased accordingly as the overdispersion increased, compared to the extended log-linear model. When the error model is additive or multiplicative with Gamma-distributed errors, the log-linear model is more efficient than the gray-scaled method. The extended log-linear model performs well overall for all three data-generating models. The loss of efficiency of the extended log-linear model is observed only when the error model is multiplicative with log-normally distributed errors, where the gray-scaled method is appropriate. However, the extended log-linear model is more efficient than the log-linear model in this case.     

刚竹毒蛾幼虫空间分布型及其在实践中的应用

本应用比较频次分布法,聚集度指标法和相关系数法,测定了刚竹毒蛾(Panatana phyllostachysae Chao)幼虫的空间分布型;同时用刀切法对其种群的平均拥挤度(m^*)进行估计。研究结果表明,其分布型属于负二项分布,其分布的基本成分为个体群,中分析并计算了林间调查的最适抽样数,列出幼虫序贯抽样分析表。     

An insect cell line discrimination method by RAPD-PCR

Summary RAPD-PCR with a tenmar single primer for discrimination of insect cell lines was devised. The base sequence of the primers used were TTCGAGCCAG, CCGCATCTAC, GAACGGACTC, and TGAGTGGGTG (GC contents were 60%). Genome DNA was extracted by modified Landry et al. (1993) method. The reaction mixture consisted of 10 μl buffer, 8 μl dNTP mixture (2.5 mM each), 4 μl primer (50 μM), Taq DNA polymerase (2.5 units), 1 μl template DNA; and the reaction was run at 94° C for 2 min (denaturation), followed by 31 cycles of 94° C for 1 min, 42° C for 1 min (annealing), and 72° C for 2 min (extension) and terminated with 72° C for 7 min. By developing the reaction products with agarose gel electrophoresis, it became evident that DNA fragments were amplified with all the primers used. Among four primers, the second primer was selected as a suitable primer for distinguishing cell lines. With this method, cell lines derived from different species were clearly distinguished.     

Synthesis of an analogue of the lipoglycopeptide membrane intermediate I of peptidoglycan biosynthesis

Summary α-Dihydroheptaprenyl-pyrophosphoryl-N-acetylmuramoyl-L-Ala-γ-D-Glu-meso-diaminopimeloyl(N ^∈-dansyl)-D-Ala-D-Ala (1), an analogue of lipid I of peptidoglycan biosynthesis, was synthesized from natural UDP-N-acetylmuramoyl-pentapeptide in three steps. Compound1 was shown to be a substrate for the MurG transferase fromEscherichia coli, even in the absence of membranes. When membranes were present, dansylated peptidoglycan was also formed.     

Urinary Thromboxane B2 in Cardiac Transplant Patients as a Screening Method of Rejection

Noninvasive methods for regular monitoring of cardiac transplant patients for acute rejection are preferable to the only currently accepted method involving frequent endomyocardial biopsies. Thromboxane A₂ (TXA₂) is synthesized in large amounts by monocytes/macrophages during organ graft rejection. It enhances T-lymphocyte clonal expansion and cytotoxic function as well as upregulating the major histocompatibility class II expression on antigen presenting cells. Experimentally increased urinary excretion of TXA₂ metabolites is associated with cardiac transplant rejection. We therefore compared urinary immunoreactive thromboxane B₂ (i-TXB₂) levels to the rejection score of the endomyocardial biopsies. In addition we graded the degree of activated lymphocytes in peripheral blood. Urinary i-TXB₂ was significantly higher in patients exhibiting medium to severe rejection than in patients without rejection (1236 ± 372 vs. 526 ± 57 pg/mL). The urine i-TXB₂ (704 ± 48 pg/mL) of all patients who participated in this study, whose endomyocardial biopsy indicated rejection, was also significantly higher than in the non-rejecting group. Increased levels of urine i-TXB₂ were associated with increased biopsy scores. Circulating activated lymphocytes was also significantly increased in patients with moderate/severe rejection compared to patients with no rejection (66 ± 11 vs. 39 ± 4 per mm (3)) (p < 0.01). Further, this study shows that urine i-TXB₂ is associated with increased endomyocardial biopsy scores (acute rejection scores) and blood lymphocyte activation. Thus we conclude that urine i-TXB₂ may be of potential value as a diagnostic screening test for helping identify cardiac transplant patients undergoing acute rejection.     

The impact of sampling frequency and sampling times on chamber-based measurements of N2O emissions from fertilized soils

An automated closed‐chamber system was developed to measure N₂O fluxes in the field. It was deployed at two N‐fertilized grassland sites in two successive years, together with replicated manual chambers, to investigate the spatial and temporal variability in fluxes, and the likely impact of sampling frequency on cumulative flux values. The automated system provided flux data at 8‐h intervals, while manual sampling was conducted at intervals of 3–7 days. The autochambers showed fluctuations in emissions not detected by manual sampling. However, integrated flux values based on the more intensive measurements were on average no more than 14% greater than those based on data from the autochambers that were obtained at the same time as manual sampling. This difference was not significant and well within the spatial variability determined with manual chambers. If daily sampling intervals were used immediately after fertilization, the agreement was closer still, increasing the confidence that can be placed in manual procedures. Diurnal variations in temperature and flux were small, and results from sampling at mid‐day were not significantly different from those based on early morning or evening sampling. Where diurnal fluctuations in temperature and flux are likely to be much larger, the autochamber/sampler system could prove very useful to quantify the effect.     

Phylogenetic relationships among six species of Epistylis inferred from 18S-ITS1 sequences

Phylogenetic relationships among six species of Epistylis (i. e. E. plicatilis, E. urceolata, E. chrysemydis, E. hentscheli, E. wenrichi, and E. galea) were investigated using sequences of the first internal transcribed spacer region (ITS-1) of ribosomal DNA (rDNA). Amplified rDNA fragment sequences consisted of 215 or 217 bases of the flanking 18S and 5.8S regions, and the entire ITS-1 region (from 145 to 155 bases). There were more than 33 variable bases between E. galea and the other five species in both the 18S region and the ITS-1 region. The affiliation of them was assessed using Neighbor-joining (NJ), maximum parsimony (MP) and maximum likelihood (ML) analyses. In all the NJ, MP and ML analyses E. galea, whose macronucleic position and shape are distinctly different from those of the other five species, was probably diverged from the ancestor of Epistylis earlier than the other five species. The topology in which E. plicatilis and E. hentscheli formed a strongly supported sister clade to E. urceolata, E. chrysemydis, and E. wenrichi was consistent with variations in the thickness of the peristomial lip. We concluded that the macronucleus and peristomial lip might be the important phylogenetic characteristics within the genus Epistylis.     

Evolution of jumping capacity in Tropidurinae lizards: does habitat complexity influence obstacle‐crossing ability?

Jumping performance is relevant for lizards in many ecological contexts and might be favoured during the colonization of structurally complex habitats. Although ground-dwelling lizards use jumps to overcome small obstacles in their natural environments, jumping capacity has been mostly studied in arboreal species. Here, we analysed the evolution of jumping behaviour and performance in lizards from eight ground-dwelling species of Tropidurinae attempting to cross obstacles of different heights in a jumping track, both when undisturbed and under continuous stimulation. To establish ecological correlates with habitat complexity, individuals from two contrasting Brazilian habitats, the arid Caatingas (sand species) and the savannah-like Cerrados (rock species), were compared. Rock species jumped more often and crossed higher obstacles than sand ones in both tests, and performed more vertical than horizontal jumps. Although sand species performed less jumps, they were more successful at crossing the obstacles presented in comparison with rock species. Phylogenetic analyses confirmed these findings and demonstrated a large divergence in jumping capacity between sister-species from different habitats. Therefore, the differences in propensity and endurance for jumping activity appear to be independent of phylogenetic relationships in Tropidurinae and likely reflect an adaptation to the contrasting environments inhabited. The ecological implications of these findings are discussed.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 393–402.     

Unifying and distinguishing diversity ordering methods for comparing communities

Diversity indices have been widely used in ecological research, but they remain problematic in that different indices may rank communities inconsistently. This problem can be solved by using diversity ordering methods, the output of which is a diversity profile in graphical form for each community being compared. In this paper, we demonstrate that existing diversity ordering methods can be classified into four groups and that within-group methods are essentially equivalent, while among-group methods are not. We find that the intrinsic diversity-related methods—i.e., the group containing the right tail-sum method, the logarithmic dominance plot, the majorization method, and the k-dominance plot—provide the most stringent test of diversity ordering, and we recommend the right tail-sum method as the method of preference for practical purposes.