Gill morphometrics in relation to gas transfer and ram ventilation in high‐energy demand teleosts: Scombrids and billfishes

This comparative study of the gill morphometrics in scombrids (tunas, bonitos, and mackerels) and billfishes (marlins, swordfish) examines features of gill design related to high rates of gas transfer and the high‐pressure branchial flow associated with fast, continuous swimming. Tunas have the largest relative gill surface areas of any fish group, and although the gill areas of non‐tuna scombrids and billfishes are smaller than those of tunas, they are also disproportionally larger than those of most other teleosts. The morphometric features contributing to the large gill surface areas of these high‐energy demand teleosts include: 1) a relative increase in the number and length of gill filaments that have, 2) a high lamellar frequency (i.e., the number of lamellae per length of filament), and 3) lamellae that are long and low in profile (height), which allows a greater number of filaments to be tightly packed into the branchial cavity. Augmentation of gill area through these morphometric changes represents a departure from the general mechanism of area enhancement utilized by most teleosts, which lengthen filaments and increase the size of the lamellae. The gill design of scombrids and billfishes reflects the combined requirements for ram ventilation and elevated energetic demands. The high lamellar frequencies and long lamellae increase branchial resistance to water flow which slows and streamlines the ram ventilatory stream. In general, scombrid and billfish gill surface areas correlate with metabolic requirements and this character may serve to predict the energetic demands of fish species for which direct measurement is not possible. The branching of the gill filaments documented for the swordfish in this study appears to increase its gill surface area above that of other billfishes and may allow it to penetrate oxygen‐poor waters at depth. J. Morphol. 2010. © 2009 Wiley‐Liss, Inc.     

Hypoxia-induced developmental plasticity of larval growth,gill and labyrinth organ morphometrics in two anabantoid fish: The facultative air-breather Siamese fighting fish (Betta splendens) and the obligate air-breather the blue gourami (Trichopodus trichopterus)

Larval and juvenile air breathing fish may experience nocturnal and/or seasonal aquatic hypoxia. Yet, whether hypoxia induces respiratory developmental plasticity in larval air breathing fish is uncertain. This study predicted that larvae of two closely related anabantid fish—the facultative air breather the Siamese fighting fish (Betta splendens) and the obligate air breathing blue gourami (Trichopodus trichopterus)—show distinct differences in developmental changes in body, gill, and labyrinth morphology because of their differences in levels of dependency upon air breathing and habitat. Larval populations of both species were reared in normoxia or chronic nocturnal hypoxia from hatching through 35–38 days postfertilization. Gill and labyrinth variables were measured at the onset of air breathing. Betta splendens reared in normoxia possessed larger, more developed gills (~3× greater area) than T. trichopterus at comparable stages. Surface area of the emerging labyrinth, the air breathing organ, was ~ 85% larger in normoxic B. splendens compared to T. trichopterus. Rearing in mild hypoxia stimulated body growth in B. splendens, but neither mild nor severe hypoxia affected growth in T. trichopterus. Condition factor, K (~ 1.3 in B. splendens, 0.7 in T. trichopterus) was unaffected by mild hypoxia in either species, but was reduced by severe hypoxia to <0.9 only in B. splendens. Severe, but not mild, hypoxia decreased branchial surface area in B. splendens by ~40%, but neither hypoxia level affected Trichopodus branchial surface. Mild, but not severe, hypoxia increased labyrinth surface area by 30% in B. splendens. However, as for branchial surface area, labyrinth surface area was not affected in Trichopodus. These differential larval responses to hypoxic rearing suggest that different larval habitats and activity levels are greater factors influencing developmental plasticity than genetic closeness of the two species.     

Gross structure of the respiratory organs and dimensions of the gill in the mud–skipper, Periophthalmodon schlosseri (Bleeker)

In Periopkrlialnwdon scldosseri the respiratory organs consist of the gills, the suprabranchial and opercular chambers. The gills are more suited for aerial than aquatic respiration as is shown by the presence of the vascular papillae, blood sinusesand dilated blood vessels in their lamellae. The gill lamellae possess a surface coat of sulphated mucopolysaccharides that prevents water loss during exposure to the air. The filaments of the outer hemibranchs in the first gill arch are reduced to nearly one quarter of those of its posterior hemibranch. The gill area in relation to body weight shows a high slope value ( b =0·93).     

Stereological estimation of the surface area and oxygen diffusing capacity of the respiratory stomach of the air‐breathing armored catfish Pterygoplichthys anisitsi (Teleostei: Loricariidae)

The stomach of Pterygoplichthys anisitsi has a thin, translucent wall and a simple squamous epithelium with an underlying dense capillary network. In the cardiac and pyloric regions, most cells have short microvilli distributed throughout the cell surface and their edges are characterized by short, densely packed microvilli. The mucosal layer of the stomach has two types of pavement epithelial cells that are similar to those in the aerial respiratory organs. Type 1 pavement epithelial cells, resembling the Type I pneumocyte in mammal lungs, are flat, with a large nucleus, and extend a thin sheet of cytoplasm on the underlying capillary. Type 2 cells, resembling the Type II pneumocyte, possess numerous mitochondria, a well‐developed Golgi complex, rough endoplasmic reticulum, and numerous lamellar bodies in different stages of maturation. The gastric glands, distributed throughout the mucosal layer, also have several cells with many lamellar bodies. The total volume (air + tissue), tissue, and air capacity of the stomach when inflated, increase along with body mass. The surface‐to‐tissue‐volume ratio of stomach varies from 108 cm^?1 in the smallest fish (0.084 kg) to 59 cm^?1 in the largest fish (0.60 kg). The total stomach surface area shows a low correlation to body mass. Nevertheless, the body‐mass‐specific surface area varied from 281.40 cm² kg^?1 in the smallest fish to 68.08 cm² kg^?1 in the largest fish, indicating a negative correlation to body mass (b = ?0.76). The arithmetic mean barrier thickness between air and blood was 1.52 ± 0.07 μm, whereas the harmonic mean thickness (τ_h) of the diffusion barrier ranged from 0.40 to 0.74 μm. The anatomical diffusion factor (ADF = cm² μm^?1 kg^?1) and the morphological O₂ diffusion capacity (D_morpholO₂ = cm³ min^?1 mmHg^?1 kg^?1) are higher in the smallest specimen and lower in the largest one. In conclusion, the structure and morphometric data of P. anisitsi stomach indicate that this organ is adapted for oxygen uptake from air. J. Morphol. 2009. © 2008 Wiley‐Liss, Inc.     

The aerobic metabolism of 14C-sugars and 14CO2 by the daughter sporocysts of Microphallus similis (JÄG) and Macrophallus pygmaeus (Levinsen) (Digenea: Microphallidae)

The sporocysts of Microphallus similis and M. pygmaeus can aerobically utilise radiosugars and ¹⁴ CO₂in vitro. Both have an EMP pathway, TCA cycle, pentose-phosphate shunt, are able to undergo transamination reactions and can synthesise some essential amino acids. Carbon dioxide fixation involves the carboxylation of phosphoenolpyruvate to form oxaloacetate.     

Isolation and characterization of acidic glycosphingolipids from the gill of the Pacific Salmon (Oncorhynchus keta): A novel hybrid-type ganglioside with isoglobo- and neolacto-Series

Monosialosyl gangliosides and sulfoglycolipids in the gill of pacific salmon, Oncorhynchus keta, have been prepared by solvent extraction and DEAE-Sephadex column chromatography. Acidic glycolipid bands (M1-M13) detected by thin layer chromatography were separated by Iatrobeads column chromatography and 13 components were characterized by TLC, compositional analysis, methylation analysis, chemical and enzymatic degradation, liquid secondary ion mass spectrometry and (1)H nuclear magnetic resonance spectroscopy. In addition to the acidic glycolipids with known structures (SM4s, SM3, GM3, LM1, GM1b and V(3)alphaFuc,IV(3)betaGalNAc-GM1a), two fractions (M11 and M13) of unknown monosialosyl gangliosides with TLC mobility slower than GM1a were isolated and characterized as having the following structure with a hybrid of isoglobo- and neolacto-series. [formula: see text] Analysis of fatty acid indicated predominance of C24:1 fatty acid in the upper band (M11) and shorter chain saturated fatty acids in the lower band (M13). The tissue concentrations of M11 and M13 were 1.15 and 0.96 mumol/kg wet weight, respectively.     

Taxonomic assessment of sharks,rays and guitarfishes (Chondrichthyes: Elasmobranchii) from south‐eastern Arabia,using the NADH dehydrogenase subunit 2 (NADH2) gene

An 829‐bp fragment of the NADH dehydrogenase subunit 2 (NADH2) gene was used to assess the taxonomic status of 1487 elasmobranch specimens, representing 52 putative species. Strong evidence was found for the existence of an undescribed Echinorhinus species and for cryptic speciation within Rhynchobatus djiddensis. The results also provide strong molecular support for the existence of two previously reported, but undescribed, guitarfish species. Potential, but less conclusive, cryptic lineage diversification was also noted in Carcharhinus leucas, Loxodon macrorhinus, Iago omanensis and Gymnura poecilura. A complex situation was found in the genus Himantura, with potentially three distinct lineages evident, one of which is probably an undescribed species, in the H. gerrardi complex. One dasyatid specimen could not be identified, but appears to be closely related to Dasyatis ushiei, while Himantura leoparda and Carcharhinus longimanus are reported from Oman for the first time. The results of the present study also reinforce previously reported geographical divisions within certain putative species, which has important implications for fishery management and conservation. © 2015 The Linnean Society of London     

Comparison of the reproductive ecology of two sympatric blacktip sharks (Carcharhinus limbatus and Carcharhinus tilstoni) off north-eastern Australia with species identification inferred from vertebral counts

Precaudal vertebral counts were used to distinguish between 237 morphologically similar Carcharhinus limbatus and Carcharhinus tilstoni and were congruent with differences in reproductive ecology between the species. In addition to differing lengths at maturity and adult body size, the two species had asynchronous parturition, were born at different sizes and the relative frequencies of neonates differed in two coastal nursery areas. Despite evidence that hybridization can occur, these differences suggest the species are largely reproductively isolated.     

Seasonal changes in the oxygen storage capacity and aerobic dive limits of the muskrat (Ondatra zibethicus)

Summary The oxygen storage capacity and partitioning of body oxygen reserves were compared in summer-and winter-acclimatized muskrats (Ondatra zibethicus). Blood volume, blood oxygen capacity, and skeletal muscle myoglobin content were higher in December than in July (P<0.02). Total lung capacity increased only slightly in winter (P>0.05). The oxygen storage capacity of a diving muskrat was calculated at 25.2 ml O₂ STPD · kg^-1 in July, compared to 35.7 ml O₂ STPD · kg^-1 in December. Blood comprised the major storage compartment in both seasons, accounting for 57% and 65% of the total oxygen stores in summer and winter, respectively. Based on available oxygen stores and previous estimates of the cost of diving, the aerobic dive limit (ADL) increased from 40.9 s in July to 57.9 s in December. Concurrent behavioral studies suggested that most voluntary diving by muskrats is aerobic. However, the proportion of dives exceeding the calculated ADL of these animals was shown to vary with the context of the dive. Only 3.5% of all dives initiated by muskrats floating in the water exceeded their estimated ADL. Provision of a dry resting site and access to a submerged food source increased this proportion to 18–61%, depending on the underwater distance that foraging muskrats were required to swim. Serial dives exceeding the estimated ADL were not accompanied by extended postdive recovery periods.Abbreviations ADL acrobic dive limit - Hb hemoglobin - Hct hematocrit - Mb myoglobin - PaO₂ arterial O₂ tension - STPD standard temperature and pressure, dry     

Effects of substrate roughening on the swimming performance of Schizothorax wangchiachii (Fang, 1936) in the Heishui River: Implications for vertical slot fishway design

Re-establishing the natural connectivity of rivers using fishways may mitigate the unfavourable effects of dam construction on riverine biodiversity and freshwater fish populations. Knowledge of the swimming performance of target species in specific regions is critical for designing fishways with a high passage efficiency. Substrate roughening with river stones of fishways is considered to improve fish swimming capacity by benefiting from reduced-velocity zones with lower energetic costs. However, the effectiveness of rough substrates in energy metabolism is rarely tested. We investigated the effect of substrate roughening on the swimming capacity, oxygen consumption and behaviour of Schizothorax wangchiachii from the Heishui River in a flume-type swimming respirometer. The results showed that substrate roughening improved critical and burst swimming speed by ~12.9% and ~15.0%, respectively, compared to the smooth substrate. Our results demonstrate that increased reduced-velocity zones, lowered metabolic rate and tail-beat frequency support our hypothesis that lower energetic costs improve fish swimming performance in rough substrate compared to smooth treatment. The traversable flow velocity model predicted that maximum traversable flow velocity and maximum ascent distance were higher over rough compared to smooth substrate fishways. Fishway substrate roughening may be a practical approach to improve fish swimming upstream for demersal riverine fish.     

Responses of the killifish (Aphanius dispar) to long-term exposure to elevated temperatures: growth,survival and microstructure of gill and heart tissues

Some fish species, such as killifish, that normally inhabit temperate water environments are also found in extreme thermal environments such as thermal springs. The extent of the adaptations involved is not known. In the present laboratory study, we exposed killifish (Aphanius dispar) acclimated to a normal thermal environment to elevated temperatures (37–40 °C) in which related killifish species live permanently. Our objective was to determine whether there is evidence that killifish have heat-shock characteristics that make permanent adaptation likely. The fish was exposed to this temperature for a period of 44 days and then compared with control fish kept at their normal temperature (24 °C) with respect to growth, survival and histopathology of gill and heart tissues. At the end of the experimental time, the percentage of body weight gain and specific growth rate were significantly lower in fish kept in thermal stress compared with the control group. Feed conversion ratio (FCR) was also significantly affected by water temperature, so that during thermal stress the values of FCR were negative. Fish condition (Condition factor: CF) did not differ significantly between both groups at the end of the experiment. On days 11 and 33, however, CF was significantly lower in the thermal stress group. The gill showed blood congestion in primary lamellae and shortened secondary lamellae in fish kept at 37–40 °C. No specific alterations were found in the cardiac tissue of fish kept in thermal stress conditions. Under thermal stress, 40% of fish survived until the end of the experiment. A preliminary conclusion drawn from this work is that A. dispar, which lives at normal temperatures, shows evidence of adaptability to elevated temperatures that could be a factor in the ability of killifish to adapt permanently over time to thermal environment.     

胶蚧属昆虫的自然分布扩散及地理起源(半翅目:胶蚧科)

在对南亚、东南亚及邻近地区胶蚧属昆虫分布资料归纳的基础上,结合近年实地调查资料,提出了胶蚧属昆虫的自然分布、扩散路线及地理起源。结果如下:胶蚧属昆虫主要分布在南亚、东南亚及邻近地区,主要包括中国、印度、巴基斯坦、孟加拉国、尼泊尔、不丹、缅甸、泰国、老挝、越南、马来西亚、印度尼西亚、菲律宾、澳大利亚等地。胶蚧属昆虫有2个分布区,即南亚分布区和东南亚分布区。国际流域恒河、印度河、布拉马普特拉河、萨尔温江-怒江、澜沧江-湄公河、元江-红河及它们的部分支流是胶蚧属昆虫扩散的通道。南亚扩散路线以印度为中心,分别向北、向西和向东3个方向扩散;东南亚扩散路线以马来西亚为中心,向北扩散。胶蚧属昆虫有2个地理起源,南亚范围以印度为中心,东南亚范围内以马来西亚为中心。胶蚧属昆虫的寄主植物是其分布扩散的先决条件,气候条件是限制分布扩散的关键因子。     

Structure and functional analysis of the microbial community in an aerobic: anaerobic sequencing batch reactor (SBR) with no phosphorus removal

The bacterial community of an aerobic:anaerobic non-P removing SBR biomass fed a mixture of acetate and glucose was analysed using several 16S rRNA based methods. Populations responsible for anaerobic glucose and acetate assimilation were determined with fluorescent in situ hybridization (FISH) in combination with microautoradiography (FISH/MAR). At 'steady state' this community consisted of alpha-Proteobacteria (26%) and gamma-Proteobacteria (14%), mainly appearing as large cocci in tetrads (i.e. typical 'G-Bacteria'). Large numbers of low G+C bacteria (22%), and high G+C Gram-positive bacteria (29%) seen as small cocci in clusters or in sheets were also detected after FISH. DGGE fingerprinting of PCR amplified 16S rDNA fragments and subsequent cloning and sequencing of several of the major bands led to the identification of some of these populations. They included an organism 98% similar in its 16S rRNA sequence to Micropruina glycogenica, and ca. 76% of the high G+C bacteria responded to a probe MIC 184, designed against it. The rest responded to the KSB 531 probe designed against a high G+C clone sequence, sbr-gs28 reported in other similar systems. FISH analyses showed that both these high G+C populations were almost totally dominated by small clustered cocci. Only ca. 2% of cells were beta-Proteobacteria. None of the alpha- and gamma-Proteobacterial 'G-bacteria' responded to FISH probes designed for the 'G-Bacteria' Amaricoccus spp. or Defluvicoccus vanus. FISH/MAR revealed that not all the alpha-Proteobacterial 'G-Bacteria' could take up acetate or glucose anaerobically. Almost all of the gamma-Proteobacterial 'G-Bacteria' assimilated acetate anaerobically but not glucose, the low G+C clustered cocci only took up glucose, whereas the high G+C bacteria including M. glycogenica and the sbr-gs28 clone assimilated both acetate and glucose. All bacteria other than the low G+C small cocci and a few of the alpha-Proteobacteria accumulated PHB. The low G+C bacteria showing anaerobic glucose assimilation ability were considered responsible for the lactic acid produced anaerobically by this SBR biomass, and M. glycogenica for its high glycogen content.     

Hypoxia impairs the digestive advantage of individual southern catfish (Silurus meridionalis) with high resting metabolic rates and postprandial metabolic responses

Empirical studies suggest that individuals with a high resting metabolic rate (RMR) are at an advantage under favourable conditions because they digest food rapidly and exhibit a greater growth potential. However, we hypothesised that high-RMR individuals have less energy available for digestion under hypoxia than they do under normoxia due to their relatively high maintenance cost. To test this hypothesis, we measured the RMR and postprandial metabolic responses of juvenile southern catfish, Silurus meridionalis, under normoxia and moderate hypoxia. The results provided the first evidence that (1) both the RMR and postprandial metabolic rate showed repeatability across different water [O₂] conditions and (2) the correlation between the RMR and postprandial metabolic traits differs with changes in environmental factors (water [O₂]). These findings suggested that the digestive advantage of individual southern catfish with a high RMR is impaired under hypoxia.     

Differentiation of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) with egg surface morphology and morphometrics using scanning electron microscopy

Aedes aegypti and Aedes albopictus are potential arboviral vectors leading to high human fatality worldwide. Efforts in the present study were made to differentiate the eggs of A. aegypti and A. albopictus morphologically and morphometrically using scanning electron microscopy (SEM). Morphometrically, these species’ eggs were 48.48% significantly different of the 33 attributes including egg dimensions, micropylar apparatus, dimensions and density of outer chorionic cells (OCCs), tubercles and width of exochorionic network. In comparison to A. aegypti eggs, A. albopictus eggs were significantly smaller and more tapered at the posterior end; however, the micropylar disc of A. aegypti was wider and had incomplete circular sectors whereas it was a narrower polygon without sectors in A. albopictus. These species were also significantly different with regards to OCC which enclose both large central and small peripheral tubercles. Specifically, the exochorionic networks in A. aegypti were interwoven, reticulated and extensively wide whereas they were narrow, prominent and solid-wall-like in A. albopictus. This feature may strengthen A. albopictus eggs against desiccation, when they are laid in containers. The morphometrical and morphological analysis of the egg’s attributes of A. aegypti and A. albopictus may be helpful in understanding egg biology as well as in species confirmation.     

Ceriometry,a combined method for chemical oxygen demand and dissolved oxygen (with a discussion on the precision of the winkler technique)

A ceriometric method is described in which Ce³⁺ salts are used for the determination of dissolved oxygen and Ce⁴⁺ salts for the determination of the chemical oxygen demand. The interference of COD in the O₂ determination, a common feature of most Winkler determinations, is corrected. The standard deviation is typically about 1% of the mean, and bias (inaccuracy) is very small.The method is simple, quick and reliable.The precision and accuracy of the Winkler method is discussed and compared with that of the Cerium method.     

昆虫携播螨-下盾螨属二新种和密卡螨属一新种(蜱螨亚纲:革螨股:厉螨科,裂胸螨科)

记述下盾螨属2新种和密卡螨属1新种：重庆下盾螨Hypoaspis chongqingensis sp．nov．t似陆下盾螨Hypoaspis terrestrisimilissp．nov．和粗刺密卡螨Melichares crassispinus sp．nov．。     

4种弹涂鱼鳃的形态度量学比较及其生态学意义

通过对背眼虎鱼亚科中薄氏大弹涂鱼(Boleophthalmus boddarti)、青弹涂鱼(Scartelaos histophorus)、新几内亚弹涂鱼(Periophthalmus novaeguineaensis)和点弹涂鱼(P.spilotus)3属4种弹涂鱼鳃参数的测定,比较了各种之间鳃的形态度量学差异。结果表明,4种弹涂鱼的鳃参数(Y)与其体重(W)均符合方程logY=log a+b logW,且各鳃参数与体重的相关性显著(R2=0.50～0.98,P0.05)。等体重的弹涂鱼相比较,青弹涂鱼的总鳃丝数、总鳃丝长(mm)、鳃丝一侧鳃小片数(/mm)、总鳃面积(mm2)和相对鳃面积(mm2/g)均最大,薄氏大弹涂鱼相应鳃参数次之,新几内亚弹涂鱼和点弹涂鱼相应鳃参数较小。弹涂鱼鳃结构的这种梯度退化,表明青弹涂鱼和薄氏大弹涂鱼水生性较强,而新几内亚弹涂鱼和点弹涂鱼陆生性较强。4种弹涂鱼的总鳃丝长和总鳃面积明显小于其他等体重水生鱼类,这与弹涂鱼的两栖生活特征相符。     

仿胭螨属1新种和革赛螨属1新种及细毛革赛螨补充描述【蜱螨亚纲：中气门目：胭螨科）

记述仿胭螨属1新种：湖北仿胭螨Rhodacarellus hubeiensis sp．nov．和革赛螨属1新种：拟羽革赛螨Gamasellus imitoplumosus sp．nov．。并对细毛革赛螨Gamasellus leptinochaetus Ma,2005进行补充描述。