Scanning electron microscopy of the post-embryonic stages of the climbing perch,Anabas testudineus

Different developmental stages, fertilized eggs through hatchlings, of the climbing perch,Anabas testudineus, have been studied by scanning electron microscopy. The surface specialization of eggs and hatchlings reveals that while the egg surface is reticulate in appearance, the hatchlings are covered with microridges. Vitelline arteries are seen at the pharyngeal and abdominal regions. They supply nutrients directly from the yolk sac to the developing embryo. Three pairs of such arteries are distinctly seen in the pharyngeal region. Mucous glands are discernible at places over the entire body surface of the embryo before the formation of scales. The skin seems to be helpful in gaseous exchange till the gills and accessory respiratory organs develop and become functional.     

Scanning electron microscopy of the respiratory organs of juvenile and adult climbing perch,Anabas testudineus

The gills and air-breathing organs of fingerlings (1–2.5 g) and adult (30 g)Anabas testudineus have been studied by scanning electron microscopy. The labyrinthine organs bear only one or two leaf-like plates in fingerlings of 1–2.5 g body weight. In very small finglerlings (1 g) no proper development of respiratory islets could be seen on the labyrinthine plates. There is evidence of the suprabranchial chambers being used for aquatic respiration in juvenile stages. In adults the inhalent and exhalent apertures become well defined with shutters developed on the first pair of gills, when they become obligatory air-breathers.     

Surface area of the respiratory organs of the Climbing perch, Anabas testudineus (Pisces: Anabantidae)

Measurements have been made of the surface area of the gills and accessory respiratory organs of Anabas in the weight range 1–120 g, and the data analysed with respect to body weight using logarithmic transformations. The slope of the regression line for total gill area (0–615) is less than that found in most fish, the number of secondary lamellae/mm decreased more rapidly with body weight than for most water-breathing species (h = -0.152). The gill area of Anabas is relatively small but when the area of the accessory organs is added, the total respiratory area is of the same order as inactive water-breathing fish. The regression coefficient for combined areas of labyrinthine organs and lining of the suprabranchial chambers (0.713) exceeds that for the gills and together with other evidence (including estimates of diffusing capacity from morphological measurements), indicates an increasing importance of air-breathing of larger specimens. The average surface area of the accessory organs available for 1 ml of air within the suprabranchial chambers was found to be 2226 mm².     

Development of the respiratory swimbladder of Pangasius sutchi

The swimbladder of Pangusius sutchi first appears on the dorsal surface of the oesophagus at about 5 days after hatching. The swimbladder has double chambers when it is separated by a medial septum at 8–10 days. Alveoli start to develop and function in air-breathing at 12–14 days. Their number is increased by subdivision, and the respiratory portion grows towards the centre. Morphometric analysis shows that the swimbladder increases in respiratory surface, volume and surface area: volume ratio during development. On a histological basis, the development of the swimbladder is divided into three distinct periods: a blind tube, a double chamber and an alveolus period. It is characteristic that the flat epithelial cell arises from a primordial cuboidal cell and that a double capillary system is arranged in the interalveolar septa. Multilamellar bodies appear and a blood-air barrier is established when the swimbladder becomes functional.     

The gill of fish larvae. Is it primarily a respiratory or an ionoregulatory structure?

Based on surface area and chloride cell number, rainbow trout Oncorhynchus mykiss gills appear initially to be more important in terms of ion balance than gas exchange. Chloride cells appear on the gill 3–6 days before hatch at 10°C. This is about 9 days before secondary lamellae, the definitive adult gas exchange structure, begin to form. At hatch, 22% of all chloride cells but only 7% of total surface area are located on the gill. This discrepancy gradually diminishes but even at complete yolk absorption the gill still seems to be about twice as important in terms of ion balance (75% of chloride cells) as gas exchange (37% of total surface area represented by gill filaments and lamellae combined). Surface area measurements and chloride cell counts reported in the literature for larvae of other species show a similar pattern suggesting that this may be a general phenomenon. If true, the implications are profound not only for developmental physiologists but also for those interested in the evolutionary history of gills and their function in adult fish.     

Fine structure of the respiratory organs of the Climbing perch, Anabas testudineus (Pisces: Anabantidae)

An electron microscopic study has been made of the three respiratory organs of climbing perch. The gill structure is similar to that of the other telcosts but the thickness of the water/blood barrier is much greater, being as great as 20 μm in some specimens. The increased thickness is due to a multilayered epithelium which is thinner (3.5–7 μm) over the marginal channel of the secondary lamellae. The other two main layers, basement membrane and pillar cell flange, are relatively thin (about 1 μm).
The pillar cells have a typical structure, but in certain regions they are contiguous with one another and line well-defined blood channels. Some of the columns of basement membrane material in such regions may be common to adjacent pillar cells.
The air-breathing organs are (a) the lining of the suprabranchial chambers , and (b) the labyrinthine plates attached to the dorsal region of branchial arches. Electron microscopy showed that their structure is well adapted for gas exchange, the air/blood barriers being only 0.12–0.3 μm, comprising an epithelial layer, basement membrane, and thin capillary endothelium. The many parallel blood channels of the respiratory islets of both organs are separated by pillar-like structures which differ from the pillar cells of the secondary lamellae. Thus the hypothesis that the air-breathing organs represent modified gills is not supported by this study.
The fine structure of the non-respiratory region of the air-breathing organs is similar to that of the skin, and includes chemoreceptor-like cells. Evidence concerning the possible homology of pillar cells with plain muscle cells is discussed.     

Environmental and developmental effects on external gill loss in the red-eyed tree frog, Agalychnis callidryas

I examined the effects of development, hatching, and oxygen availability on external gill loss in red-eyed tree frogs, Agalychnis callidryas. Under natural conditions, the arboreal embryos maintained large external gills until hatching, which occurred from 5-8 d after oviposition. At hatching, when tadpoles entered the water, external gills began to regress. In older hatchlings this process was extremely rapid. Gill circulation was lost on average within 16 min and sometimes within 5 min. Gills often regressed completely in under 2 h. Younger hatchlings reduced gill circulation, shortened and adducted their gills, then resumed normal circulation for some time after hatching; half had completely lost external gills within 24 h. Experimentally increasing the area of egg surface exposed to the air induced loss of external gills in unhatched embryos. Older hatchlings in hypoxic water without access to air maintained their external gills. This suggests that loss of external gills is a response to increased oxygen availability, rather than a response to hatching per se. Extended maintenance of external gills by large, late-hatching embryos may facilitate continued rapid development in closely packed eggs.     

Morphometries of the respiratory organs of the Indian green snake-headed fish, Channa punctata

Measurements of the dimensions of the different gills and the suprabranchial chambers have been made and the data analysed with respect to body weight using logarithmic transformations (Y = aW^b). The slope (b) for area of the total gill surface is 0–592 and for the supra-branchial chamber 0–696, and their combined respiratory surface: 0–623. The slope values for the surface areas of the 1st, 2nd, 3rd and the 4th gill arches were 0–595,0–578,0–614 and 0–572 respectively.
The slope for secondary lamellae/mm is –0138 and that for the bilateral surface area of an average-sized lamella 0–304.
These results indicate differences in growth patterns for the dimensions of the different gills. The growth-related decrease in the number of secondary lamellae/mm and size of an average secondary lamella together with evidence from "drowning" experiments and diffusing capacity calculation, suggest that this fish is better adapted for aquatic respiration than Anabas or Saccobranchus. The slopes for the total respiratory surface area and gill area seem to be comparatively low in this species.     

Surviving submerged—Setal tracheal gills for gas exchange in adult rheophilic diving beetles

The gas exchange in adult diving beetles (Coleoptera: Dytiscidae) relies on a subelytral air store, which has to be renewed in regular intervals at the water surface. The dive duration varies from a few minutes to 24 h depending on the species, activity, and temperature. However, some species remain submerged for several weeks. Stygobiont species do not ascend to the surface and gas exchange of these species remains unclear, but it is assumed that they require air filled voids for respiration or they use cutaneous respiration. In this study, we investigate the gas exchange in the running water diving beetle Deronectes aubei, which survive submerged for over 6 weeks. The diffusion distance through the cuticle is too great for cutaneous respiration. Therefore, the dissolved oxygen uptake of submerged beetles was determined and an oxygen uptake via the rich tracheated elytra was observed. Fine structure analyses (SEM and TEM) of the beetles showed tracheated setae mainly on the elytral surface, which acts as tracheal gills. Prevention of the air bubble formation at the tip of the abdomen, which normally act as physical gill in Dytiscidae, resulted in no effect in oxygen uptake in D. aubei, but this was the sole way for a submerged Hydroporus palustris to get oxygen. The setal gas exchange technique explains the restriction of D. aubei to rivers and brooks with high oxygen concentration and it may also be used by subterran living diving beetles, which lack access to atmospheric oxygen. The existence of setal tracheal gills in species in running water which are often found in the hyporheic zone and in stygobiont species supports the known evolution of stygobiont Dytiscidae from species of the hyporheic zone. For species in running water, setal tracheal gills could be seen as an adaptation to avoid drifting downstream by the current. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

Problems in meiofauna energy-flow studies

The direct estimation of energy flow through marine meiobenthic populations poses several difficulties, mainly relating to sampling problems. The usefulness of some indirect estimation methods is discussed.Direct production estimates and respiration measurements for three brackish water crustacean populations are given, indicating a relative constant proportion between population production and respiration. The production: assimilation ratio for these populations fluctuates between 0.3 and 0.4. This is contrasted to literature data revealing much higher production: assimilation ratios as determined in the laboratory for nematode populations. Using data on laboratory cultures of the nematode Monhystera disjuncta some factors that can possibly generate this discrepancy are discussed. An analysis of P:B in different life stages of this population justifies the use of a life-cycle turnover of about 3 for meiobenthic populations, provided some conditions are met. Among these is that no drastic change in productivity occurs between juveniles and adults, and that the biomass of hatchlings, not of freshly laid eggs, is considered as generative production.     

Time course of osmotic adaptation and gill energetics of rainbow trout (Salmo gairdneri R.) following abrupt changes in external salinity

Summary The physiological and biochemical responses of rainbow trout (mean weight 250 g) to abrupt increases in salinity have been investigated. An initial crisis period lasting about 30 h was characterized by an increase in plasma and muscle ions, a rapid gill dehydration and a pronounced acidosis following a transient alkalosis. Mortality was low during this period. During the following days, gradual changes resulted in new steady state levels for most parameters examined.Analysis of adenylate pool (ATP, ATP/ADP ratio and energy charge) in the gills demonstrated an increased energy demand exhibiting two phases (4 h and 3 days), and a return to freshwater values. The gill respiration rate was constant during 3 days in sea water and decreased slightly later on. It was not influenced during the reverse transfer of seawater adapted fish into fresh water at the level of either isolated gills or perfused heads.     

Effect of hatching time on time to first feed intake,organ development,enzymatic activity and growth in broiler chicks hatched on-farm

The conventional commercial hatcheries used today do not allow the newly hatched chicks to consume feed or water. Combined with natural variation in hatching time, this can lead to early hatched chicks being feed-deprived for up to 72 h before being unloaded at the rearing site. This study investigated the effects of hatching time on time to first feed intake and development of organs, digestive enzymes and productivity in terms of growth and feed conversion ratio in chicks hatched on-farm. Chicks were divided into three hatching groups (early, mid-term and late), and assessed over a full production cycle of 34 days. The results revealed that chicks remain inactive for a considerable amount of time before engaging in eating-related activities. Eating activity of 5% (i.e. when 5% of birds in each hatching group were eating or standing close to the feeder) was recorded at an average biological age (BA) of 25.4 h and a proportion of 50% birds with full crop was reached at an average BA of 30.6 h. Considering that the hatching window was 35 h in this study, the average chick probably did not benefit from access to feed and water immediately post-hatch in this case. At hatch, mid-term hatchlings had a heavier small intestine (30.1 g/kg bw) than both early (26.4 g/kg bw) and late (26.0 g/kg bw) hatchlings. Relative length of the small intestine was shorter in late hatchlings (735 cm/kg bw) than in mid-term (849 cm/kg bw) and early (831 cm/kg bw) hatchlings. However, the relative weight of the bursa fabricii was greater in mid-term (1.30 g/kg bw) than in early hatchlings (1.01 g/kg bw). At hatch, late hatchlings were heavier than early and mid-term hatchlings (P < 0.05), but by 3 days of age early hatchlings were heavier than mid-term and late hatchlings (P < 0.01). The only effect persisting throughout the study was a difference in the relative weight of the small intestine, where late hatchlings had heavier intestines than early hatchlings (P < 0.05). Thus, while there were differences between hatching groups, this study showed that the hatchlings seemed capable of compensating for these as they grew.     

The effect of environmental salinity on the level of heat shock proteins in gill epithelium of Mytilus edilis L. mussel

The composition and the level of heat shock proteins in the gill epithelium cells of mussels Mytilus edulis L. from the White Sea under different levels of environmental salinity were studied by the method of immunoblotting. In mussels maintained under normal salinity (26%), constitutive Hsp70 and protein of about 40 kDa were revealed. After long-term (11?C14 days) acclimation to 14 and 35?? of the level Hsp70 in gill epithelium cells increased. Hsp70 induction was also observed in cells of isolated gills after salinity shock at 14% for 3 and 24 h.     

Circadian timing of cricket calling song: a clock persisting from nymphs to adults

ABSTRACT. Male Australian field crickets (Teleogryllus commodus , Walker) reared in LD 12:12 h were transferred to LL at different developmental stages and the timing of their circadian calling song rhythm was analysed in regard to the previous zeitgeber. The phase settings for the onset and end of activity were similar in crickets experiencing the LD/LL transition: (i) 3–52 days after the final moult, (ii) within 24 h before the final moult, or (iii) 1–10 days before the final moult. For all groups the results reveal entrainment of the circadian mechanism at the last LD, thus excluding age-related differences. The rhythms of crickets, transferred from LD to LL as larval instars and also exposed to a reduced temperature (5–8^oC) during their last night, were delayed by about 11 h, an effect similar to that in adult crickets after a comparable cold exposure (Loher & Wiedenmann, 1981).
The results are interpreted showing that the circadian control of (the adult's) calling song already functions in the previous (non-singing) larval stages. Since the rhythmicity continued through moults and sexual maturation, it is concluded that the control centres regulating those physiological processes (e.g. pars intercerebralis, corpora allata) are not essential to the basic circadian mechanism.     

The ontogeny of complement component C3 in Atlantic cod (Gadus morhua L.)--an immunohistochemical study

The complement system in fish is well developed and plays an important role in the immune response. Very little is known about the ontogeny of C3 in fish and no study has previously been done on the development of C3 in teleosts. In this study we have detected the presence of C3 in cod larvae from the age of 1 day post hatching (p.h.) till 57 days p.h., using immunohistochemistry. The specific primary antibodies used, were produced against the beta-chain of cod C3. Immunostaining on cod larvae sections revealed that C3 is detectable in the yolksac membrane from day 1 p.h., and in liver, brain, kidney and muscle from day 2 p.h. C3 was also detected in other organs such as eye, notochord, stomach, intestines, pancreas, heart and gills at different stages of cod larval development. These findings suggest that complement is not only important in immune defence against invading pathogens but may also play a role in the formation and generation of different organs.     

Functional respiratory anatomy of a deep-sea orbiniid polychaete from the Brine Pool NR-1 in the Gulf of Mexico

Abstract. An undescribed species of Orbiniidae (Annelida; Polychaeta) is found in large numbers associated with communities of the mussel, Bathymodiolus childressi at hydrocarbon seeps on the Louisiana slope (Gulf of Mexico). Their microhabitat is often hypoxic and sulfidic, which poses serious respiratory challenges for an aerobic metazoan. They display several anatomical features that are quite unusual for this family, which likely allow them to live in their food-rich, but oxygen-limited, habitat. The anterior gills are hypertrophied whereas the posterior gills are not. These anterior gills provide the worms with a large gill surface area (≤9.9 cm²/g wet weight), which represents 90–95% of the total gill surface area. The gills contain two blood vessels: a central blood vessel, delimited by a coelomic epithelium, and an intra-epidermal vessel. The diffusion distance between this latter and the environment is only 3 μ-m in the anterior gills, which facilitates gas diffusion. Only the anterior gills are ciliated, which may also facilitate gas exchange across this respiratory surface. The gill cells also contain numerous mitochondria and other electron-dense organelles that might be involved in sulfide detoxification.     

Clonogenic hemopoietic cells (CFU-S) in mouse pre- and postnatal ontogeny

Content of three classes of clonogenic haemopoietic cells (CFU-S-7, CFU-S-11 and CFU-S-ep) was determined in haemopoietic organs of mouse during embryogenesis (10, 14 and 18 day) and postnatal ontogenesis (2, 3 and 7 day, 1, 2, 3 and 18 month). CFU-S-7 and CFU-S-11 that from big splenic colonies on 7th and 11th days of transplantation are present in liver, spleen and bone marrow at all developmental stages. However their concentration and CFU-S-7 CFU-S-11 ratio change in haemopoietic organs. CFU-S-ep that form small colonies on 11th day are observed before birth in liver and spleen and 1 week after birth there and also in bone marrow but are practically absent from haemopoietic organs of older animals. Thus, CFU-S compartment structure is characterized by definite ratio of its subpopulations. It seems to reflect functional state of haemopoietic system during development.     

Allocation of carbon to growth, storage and respiration in the vegetative barley plant

Abstract. It is proposed that the growing plant can be divided into three compartments with reference to carbon: soluble, storage and structural. Experiments carried out at 10, 15, 20 and 30°C in the light followed changes in size of these compartments in barley plants 10–24 days old. The redistribution of ^I4C photo-assimilated by 10 day old plants was monitored simultaneously. The soluble and storage compartments are a higher percentage of plant weight at lower temperatures, and are turned over rapidly at all temperatures; they form the source of respired ¹⁴C. About 30% of the ¹⁴C fixed enters structural material; in the first 24 h after labelling, for each unit of ¹⁴C entering the structural compartment, between 0–9 (at 15°C) and 3.2 (at 30°C) units of ¹⁴C are lost by respiration. At 15°C in the dark, respiratory loss of ¹⁴C is initially from soluble and storage compartments; thereafter respiration of ^I4C occurs at the expense of structural material.     

Assessment of scots pine (Pinus sylvestris L.) respiration at culmination stage of its current growth in forest-steppe zone of Pre-Baikal area

Respiration and growth of vegetative organs of the Scotch pine model trees have been studied at the culmination stage of its current growth in forest-steppe zone of Pre-Baikal area during vegetation periods in 1976–2005. The presence of a close relationship between vegetative organ respiration and the temperature and processes of their growth is the basis of the assessment of respiration, a calculation of the intensity of which is performed per the surface and absolute dry mass (a.d.m.) of these organs. Regardless of the basis for calculating the respiration rate in the studied organs, its value decreases from apical meristems towards the base of organs. The ratio between the total respiration of over- and underground pine organs during its calculation per the surface and a.d.m. was 3: 2 and almost 2: 1, respectively. The pine respiration increased approximately two times from the beginning to the end of the observation period (regardless of the base of calculation its intensity), while its average value calculated per the surface and a.d.m. during this period was 32.8 and 36.9 kg CO₂, respectively.