THE CHROMOSOMES OF TWO SPECIES OF THE GENUS AUSTRALOTETTIX RICHARDS (GRYLLACRIDOIDEA: MACROPATHINAE)

i
The chromosomes of Australotettix montanus Richards and A. carraiensis Richards have been studied. Both species share the following characteristics: the chromosome number is 2n=45 ♂-46 ♀ the sex mechanism is of the XO ♂-XX ♀ type with the X submetacentric; the X chromosome as well as two bivalents (H₁ and H₂) are heterochromatic during first prophase.
The species differ in: (a) the pattern of distribution of heterochromatic blocks in H₁; (b) the H₁ pair consists of two metacentric autosomes in A. carraiensis while these chromosomes are acrocentric in A. montanus ; (c) a medium-sized pair of autosomes is formed by subacrocentric elements in A. carraiensis while they are acrocentric in A. montanus.
The karyotypes of both species do not differ basically from that which is typical for the Macropathinae.     

Phytoecological importance,mutual redundancy and phytological threshold values of certain climatic factors

A combination of methods (intensity of indication, floristic and mesological redundancy analysis, beta-diversity analysis, principal components analysis and Wildi's interactive ranking procedure) were used to evaluate redundancy and relative phytoecological importance among 80 climatic variables in Galicia (N.W. Spain). The information they contained was found to be adequately summarized by just 3 factors thought to play a major role in regulating the distribution of the species considered in the study area and similar areas: Baudiere's QE index, mean minimum temperature in the coldest month and mean temperature range in the coldest month. For these three factors, phytoclimatic thresholds were determined by examining beta-diversity and were used to define phytoclimatic zone types.

---

Resumen Se valora la redundancia e importancia fitoecológica relative de 80 variables climáticas en Galicia (N.O. de España) empleando una combinacion de diferentes metodos (intensidad indicadora, análisis de la redundancia florística y mesológica, análisis de beta-diversidad, análisis de componentes principales y el método de ordenación interactiva de Wildi). La información contenida en esta variables es adecuadamente resumida por 3 factores que juegan un papel predominante en regular la distribución de las especies consideradas en el area de estudio y areas similares: el índice QE de Baudiere, la temperatura media de las mínimas del mes más frío y la oscilación térmica del mes más frío. Para estos factores el análisis de la beta-diversidad permitió determinar los umbrales fitoclimáticos utilizados en la definición y cartografía de las zonas fitoclimáticas.

     

An exceptional amino acid replacement on the distal side of the iron atom in proboscidean myoglobin

Summary Amino acid sequence determination of elephant myoglobin revealed the presence of the unusual substitution E7 His Gln. Stereochemical analyses suggest that the most suitable residue which can functionally substitute for His at this position in vertebrate globins is Gln. Physiochemical studies imply that the slower rate of autooxidation of elephant myoglobin is the result of this substitution which may confer some selective advantage on the species. Comparative sequence data of paenungulate myoglobins suggest that the His Gln mutation probably occurred in an ancestor of Elephantinae.     

Colony aging affects the reproductive performance of Swiss Webster females used as recipients for embryo transfer

The objective was to evaluate the influence of colony aging in a Swiss Webster (SW) outbred stock used as recipients for embryo transfer. In the first study, a retrospective analysis was performed throughout several generations during a 38-month period in 2,398 embryos transferred to 108 SW recipients. A decrease in the percentage of live pups from transferred embryos was found at the end of the period. Impairment occurred due to the incidence of maternal cannibalism that increased from 0% to 67-100% (P<0.05), while pregnancy rate (pregnant/transferred recipients) and number of pups per delivered female were not affected throughout the period (P=NS). A following study was carried out to compare the reproductive performance of SW stock vs. B6D2F1 hybrid females in a 5-year interval. The study was conducted on a total of 893 embryos transferred to 40 females (20 SW and 20 B6D2F1) in Year #1, and 514 embryos transferred to 30 females (15 SW and 15 B6D2F1) in Year #5. No cases of maternal cannibalism were found on Year #1 in any of the strains (0/10 and 0/10). However, an incidence of 44,4% (4/9) was seen on Year #5 for SW, while for B6D2F1 the incidence was 0% (0/12) (P<0.05). Further examination of the uterus showed endometrial cysts and abnormal implantation sites in SW on Year #5 but not in B6D2F1 females. In conclusion, this study reports an impairment of the reproductive performance of an early aged SW outbred stock colony mainly due to the occurrence of maternal cannibalism. This finding has important implications for embryo transfer programs conducted in mouse facilities.     

Variability in Abundance of Temperate Reef Fishes Estimated by Visual Census

Identifying sources of sampling variation and quantifying their magnitude is critical to the interpretation of ecological field data. Yet, most monitoring programs of reef fish populations based on underwater visual censuses (UVC) consider only a few of the factors that may influence fish counts, such as the diver or census methodology. Recent studies, however, have drawn attention to a broader range of processes that introduce variability at different temporal scales. This study analyzes the magnitude of different sources of variation in UVCs of temperate reef fishes off Patagonia (Argentina). The variability associated with time-of-day, tidal state, and time elapsed between censuses (minutes, days, weeks and months) was quantified for censuses conducted on the five most conspicuous and common species: Pinguipes brasilianus, Pseudopercis semifasciata, Sebastes oculatus, Acanthistius patachonicus and Nemadactylus bergi. Variance components corresponding to spatial heterogeneity and to the different temporal scales were estimated using nested random models. The levels of variability estimated for the different species were related to their life history attributes and behavior. Neither time-of-day nor tidal state had a significant effect on counts, except for the influence of tide on P. brasilianus. Spatial heterogeneity was the dominant source of variance in all but one species. Among the temporal scales, the intra-annual variation was the highest component for most species due to marked seasonal fluctuations in abundance, followed by the weekly and the instantaneous variation; the daily component was not significant. The variability between censuses conducted at different tidal levels and time-of-day was similar in magnitude to the instantaneous variation, reinforcing the conclusion that stochastic variation at very short time scales is non-negligible and should be taken into account in the design of monitoring programs and experiments. The present study provides baseline information to design and interpret results from visual census programs in temperate reefs.     

δ15N values of macroalgae as an indicator of the potential presence of waste disposal from land-based marine fish farms

The nitrogen isotope ratio (δ¹⁵N) in tissues of native macroalgae was evaluated as a means of indicating the intensity and spatial extent of organic contamination due to disposal of waste from land-based marine fish farms (LBMFFs). Three species of macroalgae from the genus Fucus and the green macroalgae Codium tomentosum were selected for study. The study was carried out at seven flat marine fish farms located in Galicia (NW Spain). Tests were carried out to determine the intra-annual variation in δ¹⁵N values and any differences between selected macroalgae. The δ¹⁵N values enrichment was observed close to the disposal point, and δ¹⁵N values varied more widely throughout the year (±5.57 ‰) at sites affected by the marine fish farm effluent compared to natural conditions (±2 ‰). No significant differences in the isotopic signals were observed in the different species studied (standard major axis). The δ¹⁵N values of macroalgae may be an ideal means of detecting the presence of LBMFFs effluents.     

The African swine fever virus prenyltransferase is an integral membrane trans-geranylgeranyl-diphosphate synthase.

In a previous study, it was shown that the protein encoded by the gene B318L of African swine fever virus (ASFV) is a trans-prenyltransferase that catalyzes in vitro the condensation of farnesyl diphosphate and isopentenyl diphosphate to synthesize geranylgeranyl diphosphate and longer chain prenyl diphosphates (Alejo, A., Yá?ez, R. J., Rodríguez, J. M., Vi?uela, E., and Salas, M. L. (1997) J. Biol. Chem. 272, 9417-9423). To investigate the in vivo function of the viral enzyme, we have determined, in this work, its subcellular localization and activity in cell extracts. Two systems were used in these studies: cells infected with ASFV and cells infected with a recombinant pseudo-Sindbis virus carrying the complete B318L gene. In this latter system, the trans-prenyltransferase was found to colocalize with the endoplasmic reticulum marker protein-disulfide isomerase, whereas in cells infected with ASFV, the viral enzyme was present in cytoplasmic viral assembly sites, associated with precursor viral membranes derived from the endoplasmic reticulum. In addition, after subcellular fractionation, the viral enzyme partitioned into the membrane fraction. Extraction of membrane proteins with alkaline carbonate and Triton X-114 indicated that the ASFV enzyme behaved as an integral membrane protein. The membrane enzyme synthesized predominantly all-trans-geranylgeranyl diphosphate from farnesyl diphosphate and isopentenyl diphosphate. These results indicate that the viral B318L protein is a trans-geranylgeranyl-diphosphate synthase, being the only enzyme of this type that is known to have a membrane localization.     

Polyprotein processing protease of African swine fever virus: purification and biochemical characterization

The purified recombinant African swine fever virus polyprotein processing protease cleaves the two GG-X sites in polyprotein pp62 with the same efficiency. Cleavage at the site that is first recognized in vivo is not a requisite for cleavage at the second site, suggesting the existence of mechanisms that control the ordered processing of the polyprotein during infection.