A new armored searobin <Emphasis Type="Italic">Paraheminodus longirostralis</Emphasis> (Teleostei: Peristediidae) from New Caledonia

A new species of armored searobin, Paraheminodus longirostralis, is described from five specimens collected from New Caledonia at depths of 412–467 m. It is distinguishable from its three known congeners in having 34 bony plates in the upper lateral row, a forward-directed spine on each plate between the 23rd–26th and 31st–32nd plates in the upper lateral row, 6–7 + 1 + 20–21 = 27–28 gill rakers, an elongate body posterior to the anus (49.9–52.1% standard length), an elongate rostral projection (53.0–59.3% head length), short upper jaw (42.1–43.4% head length), an elongate pectoral fin (70.6–79.4% head length), and long preopercular spine (39.2–57.7% head length).     

The Sphyraena obtusata group (Perciformes: Sphyraenidae) with a description of a new species from southern Japan

Sphyraena iburiensis sp. nov. is described, and taxonomic reviews are provided for S. obtusata and S. pinguis. These species, characterized by having 2 gill rakers, are defined as the S. obtusata group. Sphyraena iburiensis, known only from the Pacific coast of southern Japan, is characterized by 8.5–9.5 scales above the lateral line, a single row of scales in the groove along the lower margin of the suborbital region from the posterior tip of the maxilla to below the eye (=suborbital groove) not covered with skin, 2 distinct longitudinal stripes on the lateral surface of the body when fresh (upper stripe usually lost in preserved specimens), the lower stripe reaching the caudal-fin base just below the lateral line. Sphyraena obtusata, distributed in the Indo-West Pacific, is characterized by 5–7.5 scales above the lateral line, a single row of scales in the suborbital groove covered with skin, 2 somewhat indistinct longitudinal stripes on the lateral surface of the body when fresh (upper stripe usually lost in preserved specimens), the lower stripe joining the lateral line midway between the end of the second dorsal-fin base and caudal peduncle and extending to the middle of the caudal-fin base. Sphyraena pinguis, distributed in the Indo-West Pacific, is characterized by 7.5–9.5 scales above the lateral line, a single row of scales in the suborbital groove not covered with skin, and a single longitudinal stripe on the lateral surface of the body joining the lateral line slightly before or just below the end of the second dorsal-fin base and extending to the middle of the caudal-fin base. Seven (S. aureoflammea, S. brachygnathos, S. flavicauda, S. grandisquamis, S. langsar, S. lineata, and S. strenua) and 2 (S. chrysotaenia and S. schlegelii) nominal species are regarded as junior synonyms of S. obtusata and S. pinguis, respectively. In addition, lectotypes are designated for S. flavicauda, S. langsar, S. lineata, and S. obtusata. A key to the three species of the S. obtusata group is provided.     

<Emphasis Type="Italic">Adrianichthys roseni</Emphasis> and <Emphasis Type="Italic">Oryzias nebulosus</Emphasis>, two new ricefishes (Atherinomorpha: Beloniformes: Adrianichthyidae) from Lake Poso,Sulawesi, Indonesia

Two new species of ricefishes or buntingi, Adrianichthys roseni and Oryzias nebulosus, are described from Lake Poso, Sulawesi Tengah, Indonesia, bringing to 12 the number of endemic ricefishes known from Sulawesi. Adrianichthys roseni and its sole congener, A. kruyti, are distinguished from other relatively large-bodied ricefishes, Xenopoecilus, in having orbits that project beyond the dorsal profile of the head; paired preethmoid cartilages (versus single or absent in Xenopoecilus); and 13–16 (versus 8–13) dorsal fin rays. Also, as in A. kruyti, the lower jaw of A. roseni is enclosed in the upper jaw when the mouth is closed; however, the upper jaw is not as large and broadly expanded as in A. kruyti. Adrianichthys roseni differs further from A. kruyti in having fewer scales in a lateral series (approximately 63–65 versus 70–75), attaining a smaller maximum recorded standard length (90mm versus 109mm), and having the lateral process of the pelvic bone in line with the fifth, rather than the eighth, pleural rib. Oryzias nebulosus shares with O. nigrimas, also from Lake Poso, a unique sexual dichromatism in preserved specimens: adult males are dark gray to black, whereas females are a lighter grayish-yellow to brown. Relative to O. nigrimas, O. nebulosus is a small species (maximum recorded SL 33mm versus 51mm), with pelvic fins relatively anterior (lateral process of pelvic bone is in line with the third, fourth, or fifth, modally fourth, rather than the fourth or fifth, modally fifth, pleural rib), dorsal fin relatively anterior (origin above the 12–14th anal fin ray as opposed to the 15–17th anal fin ray), precaudal vertebrae 11–13, modally 12 (versus 13–14, modally 13), and relatively straight, narrow and slender (as opposed to curved, broad, and robust) ossified and cartilaginous portions of the gill arches. Endemic buntingi are threatened by introduction of exotic species, overfishing, and pollution. A conservation plan includes rearing native fishes for local use as ornamental fishes and possible reintroduction.     

A new species of amblycipitid catfish, <Emphasis Type="Italic">Xiurenbagrus gigas</Emphasis> (Teleostei: Siluriformes), from Guangxi,China

A new species of amblycipitid catfish is described based on five specimens (88.0–164.5mm in standard length: SL) collected from the vicinity of Duan, Guangxi Zhuangzu Autonomous Region, southern China. The new species, Xiurenbagrus gigas, is different from all other known amblycipitid catfish, but similar to X. xiurenensis by having two patches of vomerine teeth. The new species can be distinguished from X. xiurenensis by having a larger head (head length: 27.9–34.9% vs. 21.8–26.4% SL; head depth: 14.4–17.9% vs. 12.4–14.1% SL; head width: 22.4–29.4% vs. 18.1–20.3% SL), lower adipose fin (4.6–6.0% vs. 6.5–8.3% SL), shorter distance from dorsal origin to adipose origin (25.7–32.0% vs. 32.9–38.9% SL), longer dorsal fin (21.2–24.9% vs. 16.2–19.1% SL), longer pectoral fin (18.4–20.7% vs. 13.5–16.8% SL), longer pelvic fin (13.1–14.3% vs. 8.8–11.8% SL), and more gill rakers (7–9 vs. 5). Xiurenbagrus gigas, the largest known species in the family Amblycipitidae, is distributed in the Xijiang River, the longest tributary of the Zhujiang (Pearl) River basin.     

<Emphasis Type="Italic">Magadania skopetsi</Emphasis>, a new genus and species of Zoarcidae (Teleostei: Perciformes) from the Sea of Okhotsk

A new genus and species of zoarcid fish, Magadania skopetsi, is described on the basis of 17 specimens (83.4–115.9mm SL) from the intertidal zone of the northern coast of the Sea of Okhotsk, near Magadan, Russia. This species differs from other known zoarcid genera and species by having the following combination of characters: suborbital bones 5, the suborbital canal with 6–8 small pores; first epibranchial fan-shaped; palatopterygoid series reduced; supraoccipital broadly contacting exoccipital; posttemporal ventral ramus weak; upper lip continuous at symphysis; palatine teeth, pelvic fins and scales present; lateral line configuration mediolateral, incomplete, absent on posterior half of body; vertebrae 18–22+78–83=97–104. The closest genus cannot be determined cladistically except that the species is a member of the subfamily Gymnelinae. During the spawning season, M. skopetsi lives under stones near the outer marginal area of the intertidal zone.     

A bloom of Dunaliella parva in the Dead Sea in 1992: biological and biogeochemical aspects

A bloom of the unicellular green alga Dunaliella parva (up to 15 000 cells m1^–1) developed in the upper 5 m of the water column of the Dead Sea in May-June 1992. This was the first mass development of Dunaliella observed in the lake since 1980, when another bloom was reported (up to 8800 cells m1^–1). For a bloom of Dunaliella to develop in the Dead Sea, two conditions must be fulfilled: the salinity of the upper water layers must become sufficiently low as a result of dilution with rain floods, and phosphate must be available. During the period 1983–1991 the lake was holomictic, hardly any dilution with rainwater occurred, and no Dunaliella cells were observed. Heavy rain floods in the winter of 1991–1992 caused a new stratification, in which the upper 5 m of the water column became diluted to about 70% of their former salinity. Measurements of the isotopic composition of inorganic carbon in the upper water layer during the bloom (¹³C = 5.1) indicate a strong fractionation when compared with the estimated –3.4 prior to the bloom. The particulate organic carbon formed was highly enriched in light carbon isotopes ( ¹³ C = – 13.5). The algal bloom rapidly declined during the months June–July, probably as a result of the formation of resting stages, which sank to the bloom. A smaller secondary bloom (up to 1850 cells m1–1) developed between 6 and 10 m depth at the end of the summer. Salinity values at this deep chlorophyll maximum were much beyond those conductive for the growth of Dunaliella, and the factors responsible for the development of this bloom are still unclear.     

Chlorophyll fluorescence as an indicator of photosynthetic functioning of in vitro grapevine and chestnut plantlets under ex vitro acclimatization

This study reports the effects of light availability during the acclimatization phase on photosynthetic characteristics of micropropagated plantlets of grapevine (Vitis vinifera L.) and of a chestnut hybrid (Castanea sativa × C. crenata). The plantlets were acclimatized for 4 weeks (grapevine) or 6 weeks (chestnut), under two irradiance treatments, 150 and 300 mol m^–2 s^–1 after in vitro phases at 50 mol m^–2 s^–1. For both treatments and both species, leaves formed during acclimatization (so-called `new leaves') showed higher photosynthetic capacity than the leaves formed in vitro either under heterotrophic or during acclimatization (so-called `persistent leaves'), although lower than leaves of young potted plants (so-called `greenhouse leaves'). In grapevine, unlike chestnut, net photosynthesis and biomass production increased significantly with increased light availability. Several parameters associated with chlorophyll a fluorescence indicated photoinhibition symptoms in chestnut leaves growing at 300 mol m^–2 s^–1. The results taken as a whole suggest that 300 mol m^–2 s^–1 is the upper threshold for acclimatization of chestnut although grapevine showed a better response than chestnut to an increase in light.     

The mineralization and hardness of the radular teeth of the limpet Patella vulgata L.

Summary A study of the Patella vulgata radula has been made using: the scanning electron microscope in its normal and compositional contrast modes of operation, the electron microprobe analyser, ion etching with argon ions and microhardness testing.Only iron, silicon and small amounts of sulphur were detected in the radula. The teeth can be subdivided into a cusp, a junctional area where the cusp is joined to the base, and the base which is embedded in the radular membrane. From a study of longitudinal vertical and transverse sections of the mature teeth it was found that the cusp could be subdivided into a posterior iron-rich area (44–51% Fe, 1–6% Si) and an anterior silicon-rich area (22–30% Fe, 27–32% Si). The junctional zone consisted of a poorly mineralised layer at its border with the cusp and an iron-rich layer where it joined the base. The upper part of the base (5% Fe, 16% Si) could be clearly differentiated from the silicon-rich anterior and lower parts of the base (3–4% Fe, 28–35% Si). No minerals were detected in the membrane. The changes in the mineral content of the teeth cusps along the length of the radula were studied. Iron appeared in the cusps at the 25th row and the concentration increased to 28% at the 50th row. The iron was here evenly distributed throughout the cusp. Silicon appeared in the anterior part of the cusp at the 50th row and as it increased in concentration so the iron was displaced, and at the same time the concentration of iron increased in the posterior part of the cusp. Mineralization appeared to be complete by the 150th row.The teeth cusps appear to consist of 800 Å fibres grouped into 1 thick bundles and the tooth appears to be covered by a thin enamel-like layer. It is suggested that the fibres contain the silicon-rich phase and the matrix the iron-rich phase.The significance of the arrangement of the fibres and the distribution of the minerals are discussed with relation to the function of the teeth.We wish to thank Mr. A. Rees and Mr. A. Davies for their technical assistance; Prof. Lewis and Dr. James for the use of the Electron Microprobe; and the S.R.C. for their financial support.     

Decrease of polypeptides in the PS I antenna complex with increasing growth irradiance in the red alga Porphyridium cruentum

Thylakoids isolated from cells of the red alga Porphyridium cruentum exhibit an increased PS I activity on a chlorophyll basis with increasing growth irradiance, even though the stoichiometry of Photosystems I and II in such cells shows little change (Cunningham et al. (1989) Plant Physiol 91: 1179–1187). PS I activity was 26% greater in thylakoids of cells acclimated at 280 mol photons · m^–2 · s^–1 (VHL) than in cells acclimated at 10 mol photons · m^–2 · s^–1 (LL), indicating a change in the light absorbance capacity of PS I. Upon isolating PS I holocomplexes from VHL cells it was found that they contained 132±9 Chl/P700 while those obtained from LL cells had 165±4 Chl/P700. Examination of the polypeptide composition of PS I holocomplexes on SDS-PAGE showed a notable decrease of three polypeptides (19.5, 21.0 and 22 kDa) in VHL-complexes relative to LL-complexes. These polypeptides belong to a novel LHC I complex, recently discovered in red algae (Wolfe et al. (1994a) Nature 367: 566–568), that lacks Chl b and includes at least six different polypeptides. We suggest that the decrease in PS I Chl antenna size observed with increasing irradiance is attributable to changes occurring in the LHC I-antenna complex. Evidence for a Chl-binding antenna complex associated with PS II core complexes is lacking at this point. LHC II-type polypeptides were not observed in functionally active PS II preparations (Wolfe et al. (1994b) Biochimica Biophysica Acta 1188: 357–366), nor did we detect polypeptides that showed immunocross-reactivity with LHC II specific antisera (made to Chlamydomonas and Euglena LHC II).Abbreviations Bis-Tris bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane - DCPIP 2,6-dichlorophenol indophenol - -dm dodecyl--d-maltoside - HL high light of 150 mol photons · m^–2 · s^–1 - LGB lower green band - LHC I light-harvesting complex of PS I - LHC II light-harvesting complex of PS II - LL low light of 10 mol photons · m^–2 · s^–1 - ML medium light of 50 mol photons · m^–2 · s^–1 - MES 2-(N-morpholino) ethanesulfonic acid - P700 reaction center of PS I - PFD photon flux density - Trizma tris(hydroxymethyl)aminomethane - UGB upper green band - VHL very high light of 280 mol photons · m^–2 · s^–1     

Influence of cold soil and snowcover on photosynthesis and leaf conductance in two Rocky Mountain conifers

Summary The influence of cold soil and snowcover on photosynthesis and conductance of Picea engelmannii and Pinus contorta was investigated early in the growing season in the Medicine Bow Mountains, Wyoming, USA. Trees of both species growing in cold soil (<1°C) associated with snowpack had 25–40% lower leaf photosynthesis than trees in warm soils (>10°C). In cold soils leaf conductance of both species was lower, but more so in Pinus, leading to lower intercellular CO₂ concentrations and greater stomatal limitation of photosynthesis. Soil temperature had no effect on predawn and midday shoot water potentials of Pinus and Picea and lower photosynthesis and conductance did not appear to be a result of lower bulk shoot water potential. Predawn, as well as midday, water potentials of Pinus were consistently higher than Picea suggesting that Pinus may have deeper roots, although trenching experiments indicated young Picea trees have more extensive lateral root systems than similar sized Pinus trees. Young Picea trees (<2 m in height) in snowbanks were capable of utilizing warmer soil 4 m from their base. Under similar conditions Pinus in snowbanks had lower photosynthesis and conductance than controls and Pinus did not appear capable of utilizing warmer soils nearby. Under full sunlight, PPFD reflected from the snow surface was 400–1400 mol m^-2 s^-1 higher than from snow-free surfaces. This reflected light resulted in a 10%–20% increase in photosynthesis of Picea. The beneficial effect of reflected light was apparent whether or not photosynthesis was reduced by low soil temperatures.     

Re-appearance of rotifers in hypersaline Mono Lake, California, during a period of rising lake levels and decreasing salinity

The surface elevation of Mono Lake, California, rose 2 m and mixed-layer salinities declined about 5 g kg^–1 during the 3 years (1995–1997) following the decision to restrict water diversions out of the Mono Basin. Abundant (18000 m^–2) Hexarthra jenkinae de Beauchamp were noted in pelagic samples in October 1997 after three decades of absence or very low abundance. Abundance subsequently increased to 100000 m^–2 in December 1997 before declining to low numbers through 1998 and 1999. The re-appearance of Branchionus plicatilis Müller in pelagic samples occurred in September 1998. B. plicatilis areal abundance increased to 15000 m^–2 in October–December of both 1998 and 1999 but was low throughout the rest of the year. Both rotifers were noted in nearshore ponds, but were only abundant in those with salinities below 53 g kg^–1. During 1998–1999 when the salinities of the upper water column were 73–75 g kg^–1, less saline shoreline habitats may have been seeding the offshore rotifer populations.     

Feeding rate inhibition in crowded Daphnia pulex

Feeding rates of Daphnia pulex fed a range of levels of the alga Chlamydomonas reinhardi of 15 °C are strongly density-dependent. At lower densities, Daphnia (30 1^–1) fed at higher rates than crowded (270 1^–1) Daphnia which manifest a relatively depressed saturation feeding response. At 30 individuals/liter, Daphnia consumed 8.5 – 15.7 × 10⁴ cells d^–1h^–1 (on a volume basis, 12.1 – 22.2 × 10⁶ m³), at 270 L^–1 3.7 – 3.9 × 10⁴ (5.2 – 5.5 = 10⁶ m³ cells d^–1h^–1 when feeding on algae at 80 000 cells ml^–1 (11.3 × 10⁶ m³ ml^–1). The feeding rate data best fit an Ivlev feeding function. An autoallelopath might be causing the repression. Water preconditioned with crowded Daphnia completely repressed feeding in uncrowded Daphnia after six hours.     

Expression of <Emphasis Type="Italic">Escherichia coli</Emphasis> AppA2 phytase in four yeast systems

To develop an effective fermentation system for producing Escherichia coliphytase AppA2, we expressed the enzyme in three inducible yeast systems: Saccharomyces cerevisiae (pYES2), Schizosaccharomyces pombe (pDS472a), and Pichia pastoris (pPICZ A), and one constitutive system: P. pastoris (pGAPZA). All four systems produced an extracellular functional AppA2 phytase with apparent molecular masses ranging from 51.5 to 56 kDa. During 8-day batch fermentation in shaking flasks, the inducible Pichia system produced the highest activity (272 units ml^–1 medium), whereas the Schizo. pombesystem produced the lowest activity (2.8 units ml^–1). The AppA2 phytase expressed in Schizo. pombehad 60–75% lower K_mfor sodium phytate and 28% higher heat-stability at 65 °C than that expressed in other three systems. However, all four recombinant AppA2 phytases had pH optimum at 3.5 and temperature optimum at 55 °C and similar efficacy in hydrolyzing phytate–phosphate from soybean meal.Revisions requested 18 November 2004; Revisions received 7 January 2005     

An ammonia-oxidizing bacterium,Nitrosovibrio tenuis nov. gen. nov. sp.

An ammonia-oxidizing, autotroph growing, slender, curved rod was isolated from the soil of Hawaii. It is well distinguishable from any other nitrifying bacteria thus far described by their morphology. The cells are 1.1–3.0 m long and 0.3–0.4 m wide. They are motile by means of 1–4 subpolar to lateral flagella. In contrast to most of the ammonia-oxidizing bacteria the isolated vibrio is void of an extensive cytomembrane system. To categorize this not yet described species we propose to create the new genus Nitrosovibrio and to classify the isolated strain as Nitrosovibrio tenuis.     

Seasonal variation in the microbial contamination of game carcasses in an Austrian hunting area

In 2003, 50 game carcasses (ungulates) originating from one Austrian hunting ground were subject to visual examination for (fecal) contamination of the body cavities and microbiological testing of the body cavities in order to assess variations in microbial surface contamination in the season June–August compared to October–December. No carcass tested positive for the bacterial pathogens Salmonella or Listeria. Bacterial surface counts in October–December (median values: total aerobic count: 4.12 log₁₀ colony-forming-units (cfu)/cm²; Enterobacteriaceae: 2.48 log₁₀ cfu/cm²) were significantly lower than those in June–August (median values: total aerobic count: 5.65 log₁₀ cfu/cm²; Enterobacteriaceae: 3.45 log₁₀ cfu/cm²). The cooling regime (0.4 °C, 62% relative humidity) allowed no microbial growth for 96 h but was associated with weight loss of the carcasses. All carcasses had undergone a precooling phase of 8–12 h, with temperatures of 17.8±1.2 °C in the season June–August and 9.8±1.2 °C in October–December. This temperature difference was identified as the most probable effector for the observed seasonal variation. The results demonstrate the need for a continuous cool chain after evisceration of game carcasses.     

Root system development of Larix gmelinii trees affected by micro-scale conditions of permafrost soils in central Siberia

Spatial distributions of root systems of Larix gmelinii (Rupr.) Rupr. trees were examined in two stands in central Siberia: an even-aged stand (ca. 100 yrs-old) and a mature, uneven-aged (240–280 yrs-old) stand. Five larch trees of different sizes were sampled by excavating coarse roots (diameter > 5 mm) in each stand. Dimensions and ages of all first-order lateral roots were measured. Micro-scale conditions of soil temperature and soil water suction (each 10 cm deep) were also examined in relation to earth hummock topography (mound vs. trough) and/or ground floor vegetation types (moss vs. lichens). All larch trees developed superficial root systems, consisting of the aborted short tap root (10–40 cm in soil depth) and some well-spread lateral roots (n= 4-13). The root network of each tree was asymmetric, and its rooting area reached about four times the crown projection area. Lateral roots generally expanded into the upper soil layers of the mounds where summer soil temperature was 1–6°C higher than inside nearby troughs. Chronological analysis indicated that lateral root expansion started successively from lower to upper parts of each aborted tap root, and some lateral roots occurred simultaneously at several decades after tree establishment. The process of root system development was likely to be primarily linked with post-fire dynamics of rhizosphere environment of the permafrost soils.     

The distribution of Heterotrissocladius oliveri Saether (Diptera: Chironomidae) in Lake Michigan

Fifty one chironomid species were identified from 504 samples collected at depths ranging 8 to 267 m in Lake Michigan, U.S.A. Heterotrissocladius oliveri Saether occurred in 32% of these samples and had an average abundance of 22 m^–2 which was similar to other estimates from the Great Lakes. Maximum average lake-wide density was at 30 to 60 m (41 m^–2). At depths 60 m, H. oliveri was the dominant chironomid species comprising 75% of total Chironomidae. The substrate preference of H. oliveri differed within each depth regime considered: at 30–60 m, 2–3 ; at 60–120 m, 3–5 , 7–9 ; and at 120–180 m, 6–8 . Abundance was notably reduced at all depths in substrates characterized as medium silt (5–6 ). On a lake-wide basis, the distribution pattern suggested H. oliveri was most numerous from 30 to 60 m along the southwestern, eastern, and northern shorelines and at 60–120 m depths along the southern and eastern shorelines. Increased abundance in the South Basin was concurrent with evidence of increased sedimentation at 60 to 100 m. However, in several other areas of the lake, high densities were associated with medium to very fine sands relatively free of silts and clays. This observation suggested occurrence of H. oliveri was minimally affected by sediment type.Widely variable, but generally elevated water temperatures likely prevent H. oliveri from establishing a substantial population density at depths < 30 m. With increased depth, temperature fluctuation is negligible and food is more stable, though the source is variable. Factors limiting abundance of H. oliveri at depths 30 m were related to decreased food supply due to distance from shore, food sources of lower value (clays), and, most importantly, to reproductive replenishment.Although still oligotrophic in nature, high density occurrences in both high and low sedimentation areas of the lake suggest the trophic indicator status of H. oliveri might be broader than previously thought.     

Adaptive photosynthetic strategies of the Mediterranean maquis species according to their origin

In consideration of their origin the adaptive strategies of the evergreen species of the Mediterranean maquis were analysed. Rosmarinus officinalis L., Erica arborea L., and Erica multiflora L. had the lowest net photosynthetic rate (P_N) in the favourable period [7.8±0.6 mol(CO₂) m^–2s^–1, mean value], the highest P_N decrease (on an average 86 % of the maximum) but the highest recovery capacity (>70 % of the maximum) at the first rainfall in September. Cistus incanus L. and Arbutus unedo L. had the highest P_N during the favourable period [15.5±5.2 mol(CO₂) m^–2s^–1, mean value], 79 % decrease during drought, and a lower recovery capacity (on an average 54 %). Quercus ilex L., Phillyrea latifolia L., and Pistacia lentiscus L. had an intermediate P_N in the favourable period [9.2±1.3 mol(CO2) m^–2s^–1, mean value], a lower reduction during drought (on an average 63 %), and a range from 62 % (Q. ilex and P. latifolia) to 39 % (P. lentiscus) of recovery capacity. The Mediterranean species had higher decrease in P_N and stomatal conductance during drought and a higher recovery capacity than the pre-Mediterranean species. Among the pre-Mediterranean species, P. latifoliahad the best adaptation to long drought periods also by its higher leaf mass per area (LMA) which lowered leaf temperature thus decreasing transpiration rate during drought. Moreover, its leaf longevity determined a more stable leaf biomass during the year. Among the Mediteranean species, R. officinalis was the best adapted species to short drought periods by its ability to rapidly recover. Nevertheless, R. officinalis had the lowest tolerance to high temperatures by its P_N dropping below half its maximum value when leaf temperature was over 33.6°C. R. officinalismay be used as a bioindicator species of global change.This revised version was published online in March 2005 with corrections to the page numbers.     

Ectothiorhodosinus mongolicum gen. nov., sp. nov., a New Purple Bacterium from a Soda Lake in Mongolia

A new nonmotile purple sulfur bacterium (strain M9) was isolated from the steppe soda lake Lake Dzun Uldziin Nur (pH 9.4; mineralization, 3.3%) situated in southeastern Mongolia. Individual cells appear as vibrios 0.3–0.5 × 0.7–1 m in size. The dividing cells often do not separate from each other, forming an almost closed ring. The internal photosynthetic membranes are represented by concentric lamellae lining the cell wall. Photosynthetic pigments are bacteriochlorophyll a and carotenoids of the spirilloxanthin series. The main carotenoid (>96%) is spirilloxanthin. Two typical light-harvesting complexes (LH1 and LH2) are present in the membranes in a 1 : 1 ratio. The bacterium is an anaerobe and facultative photoorganoheterotroph. Photolithoautotrophic growth on sulfide is scarce. Thiosulfate is utilized as an electron donor only in the presence of organic matter. Globules of elemental sulfur are formed as an intermediary product of sulfide and thiosulfate oxidation and are deposited outside the cells. The end product of oxidation is sulfate. In the presence of sulfide and carbonates, acetate, lactate, malate, pyruvate, propionate, succinate, and fumarate are used as additional sources of carbon in anoxygenic photosynthesis. Vitamins are not required. The bacterium is an alkaliphile, the pH optimum is at 8.3–9.1, the pH range is 7.6–10.1. The optimum NaCl concentration in the medium is 1 to 7%; the range is 0.5 to 0.9%. The optimum carbonate content in the medium is 2%; the range is 1 to 10%. The best growth occurs at 30–35°C. The DNA G+C content is 57.5 mol %. According to the results of analysis of the 16S rRNA gene sequences, the new isolate M9 belongs to the phylogenetic cluster containing representatives of the family Ectothiorhodospiraceae within the class Gammaproteobacteria. In this class, the new isolate forms a new branch, which occupies an intermediate position between the representatives of the genera Ectothiorhodospira and Thiorhodospira. Based on the phenotypic and genetic characteristics, the new purple sulfur bacterium was assigned to a new species of a new genus of the family Ectothiorhodospiraceae, Ectothiorhodosinus mongolicum gen. nov., sp. nov.     

Stomatal conductance in a tropical xerophilous shrubland at a lava substratum

Diurnal variation in leaf stomatal conductance (g _s) of three xerophilous species (Buddleia cordata, Senecio praecox and Dodonaea viscosa) was measured over a 10-month period during the dry and wet seasons in a shrubland that is developing in a lava substratum in Mexico. Averaged stomatal conductances were 147 and 60.2 (B. cordata), 145 and 24.8 (D. viscosa) and 142.8 and 14.1 mmol m^–2 s^–1 (S. praecox) during the wet and dry season respectively. Leaf water potential () varied in a range of –0.6 to –1.2 (S. praecox), –0.6 to –1.8 (B. cordata) and –0.9 to –3.4 MPa (D. viscosa) during the same measurement periods. Stomata were more sensitive to changes in irradiance, air temperature and leaf–air vapour pressure difference in the rainy season than the dry season. Although stomatal responses to were difficult to distinguish in any season (dry or rainy), data for the entire period of measurement showed a positive correlation, stomata tending to open as increased, but there is strong evidence of isohydric behaviour in S. praecox and B. cordata. A multiplicative model relating g _s to environmental variables and to accounted for 79%–83% of the variation of g _s in three sites (pooled data); however, the performance of the model was poorer (60%–76%) for individual species from other sites not included in the pooled data.