Purification and Some Properties of Two Carboxypeptidases from the Hepatopancreas of the Crab Paralithodes camtschatica

High activity of carboxypeptidases was detected in the hepatopancreas of the crab Paralithodes camtschatica, while aminopeptidase activity in this tissue was low. Two crab carboxypeptidases were purified by chromatography on DEAE-cellulose, phenyl-Sepharose, and Sephadex G-75 to homogeneity. The molecular weight values of carboxypeptidases I and II were 40,000 and 37,000, respectively. The isoelectric point value for both carboxypeptidases was 4.5. The crab carboxypeptidases were activated by NaCl, with maximal activity of carboxypeptidases I and II at 1.0 M and 0.6 M NaCl, respectively. Using 19 N-blocked dipeptides with the general structures Bz-Gly-X and Z-Gly-X, broad substrate specificity of the purified enzymes was demonstrated. Under optimal conditions the values of K _m and k _cat for the hydrolysis of Bz-Gly-l-Phe, Bz-Gly-l-Arg, and Bz-Gly-l-Lys by crab carboxypeptidases were determined. Inhibition data led to classification of the crab enzymes as metallopeptidases. Both carboxypeptidases were stable under neutral and mildly alkaline conditions. In addition, the presence of 1 M NaCl decreased the thermostability of the crab carboxypeptidases. Received August 13, 1999; accepted November 19, 1999.     

New shell acquisition in the hermit crab,Pagurus geminus

The process of how the hermit crab,Pagurus geminus, acquires a new shell was investigated in the natural habitat at Ezura in Shirahama, Wakayama Prefecture, during the non-breeding season, and the following results were obtained. Hermit crabs acquired new shells most frequently by shell exchange between 2 individuals and occasionally by attacking snails. Acquisition through location of empty shells was not found. At the snail attacking site or the site of shell exchange attempts, sometimes many other individuals appeared and, frequently, confusing or complex shell changes were observed. The importance of introduction of fresh shells to a hermit crab population and the possibility for a certain individual to acquire a shell introduced by others through shell exchange attempts are discussed.     

The influence of H2S on reproduction rate in paramecium caudatum

Conclusion Sulfhydryl in H₂S and Na₂S in proper concentration, accelerates the reproduction rate ofParamecium caudatum. This fact is further support for the thesis ofHammett that the -SH group is an essential stimulus to growth by increase in cell number.     

Accumulation of organelles at the ends of interrupted axons

Summary Proximal and distal stumps of the sciatic nerve of rats were examined with the light and electron microscope in the course of 48 hours following nerve crush. On both sides of the lesion organelles accumulate in axons beyond regions disorganized by injury. A stretch of clear axoplasm filled with fine granules usually separates the cone of accumulating particles from the damaged part of the fibre. From two hours onwards closely packed vesicles, tubules, mitochondria and other organelles form dense pellets which fill up the whole lumen of the fibre. Further away from the fibre tip organelles are stranded at the circumference only, whereas the central core is occupied by neurofilaments. In a number of fibres no pellets are observed and only a moderately increased network of axoplasmic reticulum is seen at the fibre ends.Measurements on isolated fibres have shown that the length of the pellet increases with time on both sides of the lesion up to 18 hours after crush; thereafter the elongation is arrested in the distal stump, while in the proximal stump it continues further at a slower rate.The authors wish to acknowledge gratefully the technical assistance of Mrs. M. Sobotková, Mr. M. Doubek, Mrs. J. Waryszewska and Mrs. B. Lwowska.     

Ultrastructural study on the release of neurosecretory material from the sinus gland of the land crab,Gecarcinus lateralis

Summary Sites of release of neurosecretory material were examined in a neurohemal organ of decapod crustaceans, the sinus gland of the land crab, Gecarcinus lateralis. Such discharge into the circulation seems to occur primarily at interfaces between the neurosecretory axons and the acellular stromal sheath which is interposed between parenchyma and hemolymph. The evidence obtained from electron micrographs of adult specimens indicates that more or less intact secretory granules are released into the extraaxonal space primarily by the process of exocytosis. Synaptic-type vesicles are clustered in parts of neurosecretory axons facing the stromal sheath. Such vesicles are thought to result from rearrangement of membranes temporarily fused at the release site and to a minor degree from fragmentation of neurosecretory vesicles within the axon. The presence of nonmarginal vesicles and the occasional appearance of free intraaxonal dense material are interpreted as indications of a second, probably less frequent, mode of release of neurosecretory material.Supported by grants AM-3984, NB-00840, and NB-05219 from the U.S.P.H.S., administered by Dr. Berta Scharrer.I am greatly indebted to Mrs. Sarah Wurzelmann for her excellent technical assistance. I thank Dr. Dorothy E. Bliss for contributing the animals used in this study, and Mr. Murray Altmann for technical advice.     

Periodicity of extinction and recolonization of the West Indian topshell Cittarium pica in the Quaternary of Bermuda (Gastropoda: Trochoidea)

Hermit‐crab transported shells of the West Indian top shell Cittarium pica occur in numerous terrestrial fossil deposits on Bermuda, which is the most remote outpost of this Caribbean species. Cittarium is so far known only from deposits of interglacial ages corresponding to marine isotope stages (MIS) 11, 9, 5e, and 1 (Holocene). In at least the cases of MIS 11 and 5e, Cittarium appears at the very beginning of the interglacial. The species is definitely absent from well‐stratified cave deposits of the last glacial (MIS 4–2). It is hypothesized that colder sea‐surface temperatures (SSTs) during glacial periods caused Cittarium to be extirpated on Bermuda, and that it has made at least four independent colonizations of the island in the past 400 000 years. Because of the limited larval life of Cittarium, the window for colonization may be a very narrow period at the onset of interglacials when the SST has risen sufficiently to make Bermuda habitable but the velocity of the Gulf Stream is still sufficiently rapid to transport viable larvae from the Bahamas. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 235–243.     

The influence of sulfhydryl and sulfoxide on differential growth within the regenerating chela of the hermit crab (Pagurus Longicarpus)

Protoplasma - The basic fact out of which all others derive in this study of the regenerating right chela of the Hermit crab, is that mitotic activity is accelerated by sulfhydryl and retarded by...     

Salinity regulates <Emphasis Type="Italic">N</Emphasis>-methylation of phosphatidylethanolamine in euryhaline crustaceans hepatopancreas and exchange of newly-formed phosphatidylcholine with hemolymph

Phosphatidylcholine (PC), the main phospholipid in eukaryotes, is synthesized via two different routes, the phosphatidylethanolamine N-methyl transferase (PEMT) and the CDP-choline pathways. We previously showed in euryhaline fish that salinity impacts the relative contribution of the two pathways for PC biosynthesis, with PEMT pathway being activated in the liver of sea water (SW)-adapted animals. To address the occurrence of such phenomenon in other animals we performed in vivo metabolic studies in two crustacean species: the Chinese crab (Eriocheir sinensis) and the green crab (Carcinus maenas). In both species, the levels of PC and phosphatidylethanolamine in hepatopancreas and hemolymph were not modified by SW-adaptation. In E. sinensis, SW-adaptation activated PC labeling from l-(U-¹⁴C)-serine in the hepatopancreas and resulted in an increased ratio of PC specific activities between hemolymph and hepatopancreas. In C. maenas, incorporation of l-(3-³H)-serine and l-(2-¹⁴C)-ethanolamine into PC of hepatopancreas was strongly inhibited after acclimation to fresh water (FW). The results show that PC synthesis via the PEMT pathway and its subsequent release into hemolymph are both activated in SW- compared to FW-adapted animals. SW-adaptation also resulted in increased tissue concentrations of betaine and labeling from l-(U-¹⁴C)-serine, suggesting that the PEMT-derived PC is used for the synthesis of organic osmolytes. The physiological relevance of these observations is discussed.     

Hermit crab biocoenoses: a worldwide review of the diversity and natural history of hermit crab associates

The symbiotic associates of hermit crabs (excluding parasites and flora) are reviewed worldwide. The review includes species found on the shells occupied by hermit crabs (epibiotic species), species boring into these shells (endolithic species), species living within the lumen of the shell (either free-living or attached to the shell), species attached to the hermit crabs themselves, and hypersymbionts. In total over 550 invertebrates, from 16 phyla are found associated with over 180 species of hermit crabs. Among these associates, 114 appear to be obligate commensals of hermit crabs, 215 are facultative commensals, and 232 are incidental associates. The taxa exhibiting the highest number of associates are arthropods (126), polychaetes (105), and cnidarians (100). The communities of species associated with Dardanus arrosor, Paguristes eremita, Pagurus bernhardus, Pagurus cuanensis, and Pagurus longicarpus are the best studied and harbor the most diverse assemblages of species. While trends in biodiversity of hermit crab assemblages do not follow predicted patterns (e.g., hermit crabs within the Indo-West Pacific do not harbor more species than those from temperate regions), this is suggested to reflect a lack of sampling rather than a true representation of the number of associates. Hermit crabs date to at least the Cretaceous and provided a niche for a number of groups (e.g., hydractinians, bryozoans, polydorids), which were already associates of living gastropods. Apparently hermit crab shells initially supplied a substrate for settlement and then these symbiotic relationships were reinforced by enhanced feeding of symbionts through the activity of the hosts. Through their use and recycling of gastropods shells, hermit crabs are important allogenic ecosystem engineers in marine habitats from the intertidal to the deep sea. Hermit crabs benefit from some symbionts, particularly cnidarians and bryozoans, through extension of shell apertures (alleviating need to switch into new shells) and by providing protection from predators. However, hermit crabs are also negatively impacted (e.g., decreased reproductive success, increased predation) by some symbionts and a review of egg predators is provided. Thus, the symbiotic relationships between hermit crabs and many associates are difficult to characterize and often exhibit temporal changes depending on environmental and biological factors. Research on the biology of these symbionts and the costs/benefits of their associations with hermit crabs are analyzed. While some associates (e.g., Hydractinia spp.) have been studied in considerable detail, for most associations little is known in terms of the impacts of symbionts on hosts, and future experimental studies on the multitude of relationships are suggested.     

Hermit crabs,humans and crowded house markets

There is a complex and dynamic interrelationhip between hermit crabs, humans and the coastal environment. Hermit crab homes (shells) are often hard to come by, but humans are helping out by piling middens of shells and rubbish on beachers. Hermit crabs are useful to humans as fishing bait, pets and living wasted disposal systems, and so useful to other animals that they may even be hijacked.     

Vorkommen und Eigenschaften der proteolytischen Enzyme des Magensaftes und der Mitteldarmdrüse des Flußkrebses Astacus astacus (L.) und Cambarus affinis (Say)

Zusammenfassung Es werden die Exopeptidase- und Dipeptidaseaktivitäten des Hepatopankreas und Magensaftes von Astacus astacus (L.) und Cambarus affinis (Say) quantitativ bestimmt (Durchschnittswerte von ca. 90 Tieren). Die besonders im Magensaft vorkommende Carboxypeptidase hydrolysiert Carbobenzoxyglycyl-l- phenylalanin und Carbobenzoxy-l-glutamyl-l-tyrosin ungefähr gleichstark (pH-Optimum 7,6 bzw. 7,0). Im Vergleich zur kristallisierten Pankreascarboxypeptidase wird das Magensaftenzym stärker durch Hydrozimtsäure als durch o-Phenanthrolin gehemmt. SH-Gruppen sind für die Wirkung nicht nötig. Die Leucinamid- und Leucin--naphthylamid-Hydrolyse ist nicht auf die klassische Leucinaminopeptidase, sondern auf eine metallionenunabhängige und puromycinempfindliche Arylamidase-ähnliche Wirkung (pH-Optimum 7,7–8,0) zurückzuführen. Amidase- und Dipeptidase (Substrat: Glycyl-l-lencin)-Wirkung sind besonders im Hepatopankreas aktiv.

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Occurrence and properties of proteolytic enzymes in the gastric juice and hepatopancreas of the crayfishes Astacus astacus (L.) and cambarus affinis (Say)I. Exopeptidases

Summary The exopeptidase and dipeptidase activities of the hepatopanereas and gastric juice of Astacus astacus (L.) and Cambarus affinis (Say) were determined (mean values from approximately 90 exemplares). The carboxypeptidase which was highly active in the gastric juice hydrolyzes carbobenzoxyglycyl-l-phenylalanine and carbobenzoxy-l-glutamyl-l-tyrosine at about the same rate (pH-optimum at 7,6 and 7,0 respectively). Compared with the crystalline pancreas carboxypeptidase the gastric juice enzyme was stronger inhibited by hydrocinnamic acid than by o-phenanthroline. Sulfhydryl groups are not essential for the enzyme action. The observed hydrolysis of leucine amide and leucine--naphthyl amide could not be attributed to the classic leucine aminopeptidase but to an arylamidase like action (pH Optimum 7,7 to 8,0) which was independent of metal ions and puromycin-sensitive. The amidase and dipeptidase (substrate: glycyl-l-leucine) are mainly localized in hepatopanereas.

     

Variation on a theme of herbivory: Corallina–hermit crab relationship on a temperate‐subtropical rocky shore

Elucidation of species interactions involving multiple processes is an important task in ecology, as different processes may operate in non‐apparent, opposing directions. While herbivory is a major form of interspecific interaction affecting plants, calcareous algae are generally thought to be protected from herbivory due to CaCO₃ deposition. However, field observations and experiments in temperate‐subtropical intertidal rockpools showed that hermit crabs (Paguroidea, Decapoda) did not ingest Corallina but cut short its fronds. We tested the implications of this frond‐cutting behaviour with field experiments where hermit crab density and Corallina frond length were artificially manipulated. Hermit crab guts were fuller and contained more microscopic animals when Corallina fronds were shorter, suggesting that frond‐cutting affects accessibility to food resources that exist in the basal part of algal mat. Corallina showed compensatory growth when fronds were artificially reduced in length/density, simulating the cutting by hermit crabs. Frond density increased, probably due to increased exposure to light of the basal part of Corallina coupled with a reduction in apical dominance. The present study revealed a direct, non‐trophic relationship between hermit crabs and Corallina in which the former affected the latter for gaining access to food resources. Overall, the combination of positive and negative effects of hermit crab led to a positive, facilitative effect on Corallina. In terms of the effect on algae or plants, this relationship is functionally analogous to herbivory, without involving direct consumption. We discuss the problem of extending the concept of ecological engineering to herbivory and herbivory‐like phenomena and suggest the term ‘pseudo‐herbivory’ to describe relations in which animals have non‐trophic but herbivory‐like effects on plants/algae, as seen in the hermit crab–Corallina relationship.     

Wintering destinations of Monterey Hermit Thrushes (Catharus guttatus slevini)

Across their broad North American distribution, Hermit Thrushes (Catharus guttatus) exhibit extensive yet subtle intraspecific variation in morphology and diverse migration patterns, causing considerable debate regarding their systematics and an incomplete understanding of their migratory geography. To better understand the fall migration and wintering destinations of Hermit Thrushes in coastal California, we deployed geolocators on individuals of the subspecies C. g. slevini breeding in the Santa Cruz Mountains of the Coast Ranges. In 2014, we captured 20 Hermit Thrushes in Big Basin Redwoods State Park using mist‐nets and attached geolocators. In 2015, we retrieved tags from 13 birds. Tagged Hermit Thrushes left the breeding area between 1 and 19 September 2014 and arrived in wintering areas in Baja California Sur and northwestern mainland Mexico between 24 September and 13 October 2014. The average distance between breeding and wintering areas was 1617 ± 217 (SD) km, and the average duration of fall migration was 22.5 ± 6.4 (SD) days. Our results suggest that Hermit Thrushes breeding in Big Basin winter in a highly concentrated region of western Mexico including Baja California Sur and southwestern Sonora or northwestern‐most Sinaloa; we found no evidence that Big Basin birds overwintered in the southwestern United States. Our results also confirm the existence of chain migration for Hermit Thrushes in California. Because C. g. slevini exhibits a limited distribution in both breeding and wintering areas and their morphology and song suggest adaptation to their habitat, we recommend exploration of fine‐scale genetic structure of coastal California’s Hermit Thrushes to determine the extent of evolutionary divergence in this subspecies.     

Cellular basis for polarized light perception in the spider crab,Libinia

Summary Differential increases in the numbers of pinocytotic vesicles, multivesicular bodies and total complex bodies occurred in the cytoplasm of specific photoreceptor cells in the compound eye of the crab Libinia exposed for six hours to polarized light with various e-vector orientations. These data coupled with previous results on the same species proved that the seven retinular cells in each ommatidium formed two functional groups selectively light adaptable by e-vectors oriented 90° apart. One group (Channel I, comprising Cells 1, 4 and 5) was more affected by horizontal polarization; the other (Channel II, comprising Cells 2, 3, 6 and 7) was more affected by vertical polarization.This confirmed by a quite independent technique the conclusion reached from electrophysiological experiments on the crab Cardisoma that decapod compound eyes have two orthogonal polarization analyzer channels. In addition the present data showed that both channels occur in each ommatidium as hypothesized on previous electron microscopic evidence and that the axes of maximum absoprtion in the two retinal channels were parallel to the long axes of their cells' rhabdom microvilli, horizontal in Channel I and vertical in Channel II. The latter relations in turn supported the hypothesis that the dichroism of rhodopsin was fundamental to the analyzer mechanism.This research has been supported by U. S. Air Force Grant AFOSR 1064 and NASA Grant NGR 07-004-055. The authors wish to thank Professor Joseph G. Gall for generously sharing his electron microscope facilities.     

Vacancy Chains Provide Aggregate Benefits To Coenobita clypeatus Hermit Crabs

Vacancy chain theory describes a unique mechanism for the sequential distribution of animal resources across multiple individuals. This theory applies to any resources, such as shelters or nest sites, that are discrete, reusable, and limited in use to single individuals or groups at one time. Hermit crabs rely on gastropod shells for shelter, and a single vacant shell can initiate a chain of sequential shell switches that distributes new resources across many individuals. Using the terrestrial hermit crab Coenobita clypeatus , we examined the previously untested theoretical prediction that this process will yield trickle-down resource benefits to vacancy chain participants (aggregate benefits). In laboratory experiments, we measured improvements in shell quality when a single vacant shell was provided to groups of eight crabs. We found that crabs participating in vacancy chains (averaging 3.2 individuals) gained significant reductions in their shell crowding. In addition, vacancy chains terminated early when experimental groups included a single crab occupying a damaged shell, because damaged vacancies always remained unoccupied. Hermit crabs in damaged shells were more likely to win resource contests for high quality shells against size-matched hermit crabs in crowded shells. Finally, field additions of many new shells to an island population of C. clypeatus hermit crabs reduced average shell crowding for crabs of all sizes, possibly from propagation of benefits through vacancy chains. These results provide empirical support for the theoretical prediction that vacancy chains should provide benefits distributed across many vacancy chain participants. Since shelter-based vacancy chains likely occur in other animals, additional studies of vacancy chain processes should provide new insights into resource acquisition behaviors in diverse animal groups.     

Larval release behaviors of the striped hermit crab, Clibanarius vittatus (Bosc): Temporal pattern in hatching

Ovigerous hermit crabs, Clibanarius vittatus (Bosc), were examined in the laboratory to (1) determine if the time of larval release is a synchronous event, (2) determine the influence of a damaged gastropod shell during the egg hatching process, and (3) describe larval release behaviors. Ovigerous hermit crabs from natural light:dark (LD) and tidal cycles were moved to constant conditions 2-3 days prior to the predicted time of larval release. Larval release was synchronous, occurring near the time of expected sunset. Females with early-stage embryos placed under constant conditions displayed a free-running circadian rhythm, suggesting that the rhythm is under endogenous control. Hermit crabs with early-stage embryos that were placed under a shifted LD cycle (advanced 12 h relative to the ambient photoperiod) before being placed under constant conditions advanced their larval release rhythm by 12 h, indicating the rhythm can be entrained by the LD cycle. Hermit crabs with an intact shell released larvae in bursts at sunset over several consecutive nights (period = 24.2 h). In contrast, hermit crabs with damaged shells released larvae at different times over the course of a single day. Ovigerous females with intact shells exhibit several stereotypical hatching behaviors. The female stands on her walking legs and thrusts her abdomen, moving the shell in an oscillating motion. This movement may assist in breaking the outer membrane of the egg case. The female generates a water current inside the shell with her scaphognathite and mouthparts, which transports the newly hatched larvae out of the shell. Females in damaged shells did not display these behaviors; instead, larval release was a prolonged event with little movement of the female, and often the newly hatched larvae were not viable. These results indicate that an intact shell plays an important role in the hatching process for this hermit crab.     

The Structure and Density of Aggregations of the Hermit Crab <Emphasis Type="Italic">Pagurus proximus</Emphasis> Komai, 2000 in Epibiosis of the Brown Alga <Emphasis Type="Italic">Costaria costata</Emphasis> (C. Agardh) De A. Saunders, 1895 in the Sublittoral Zone of Vostok Bay,Sea of Japan

A study of epibiosis of the brown alga Costaria costata in the sublittoral zone of Vostok Bay, Sea of Japan during the spring and summer of 2016 showed that hermit crabs of the following four species accounted for approximately 85% of the total biomass: Pagurus proximus, P. minutus, P. brachiomastus, and P. middendorffii. Of these, the most abundant one (96.5% of the total number of hermit crabs) was P. proximus, the mean aggregation density of which on C. costata (429 ± 221 ind./m²) was higher by an order of magnitude than that in the adjacent area of the bouldery bottom. The size ranges of males and females of this species in aggregations on boulders and those on C. costata were similar, with a predominance of larger individuals on algae. In the size–frequency distribution, three groups of individuals corresponding to three size–age cohorts were differentiated. The male-to-female ratio was 1 : 1.7. Hermit crab aggregations on C. costata are ephemeral; their existence is determined by the duration of the period of algae development, that is, from late spring to the middle of the summer.     

Structure and function of the hemocyanin from a semi-terrestrial crab,Ocypode quadrata

Summary Structural and functional studies of the hemocyanin of the semi-terrestrial ghost crab,Ocypode quadrata, demonstrate a variety of differences in comparison to the hemocyanin of aquatic crabs. These differences may be related to the terrestrial habit of this crab. Unlike aquatic crabs, the major (56%) blood component is the hexamer; the remaining 44% is dodecamer. The hexamers and dodecamers are not in rapid equilibrium. Electrophoretic analysis of the subunit composition indicates three major components referred to as 1, 3, and 4, and one minor component referred to as component 2. These components, although electrophoretically distinct, are alike immunologically. Components 1 and 2 are essentially absent from purified hexamers, whereas they compose 1/3 of the subunits in dodecamers. These results suggest that they are involved in linking hexamers to form dodecamers, and that two, rather than one, subunits are involved in the bridge. Oxygen-binding measurements show a higher degree of cooperativity, and a much reduced allosteric effect ofl-lactate on the dialyzed hemocyanin as compared to the hemocyanin of aquatic crabs. Exercise rapidly, induces a large drop in hemolymph pH (0.5 units) and a corresponding increase in lactate concentrations (to 10 mM).     

Oxygen and carbon dioxide transport by the haemocyanin of an amphibious crab,Holthuisana transversa

Summary The oxygen and carbon dioxide transporting properties of the haemolymph from an amphibious Australian crab,Holthuisana transversa were investigated. Within the temperature range 15 to 35°C increasing temperature markedly decreased oxygen affinity (H=–54 kJ·mol^–1). The Bohr effect was small at all temperatures with a mean value of –0.13. Over the temperature range 15–35°C there was a significant increase in the cooperativity of oxygen binding. Changing the concentration of Ca,l-lactate or haemocyanin in the haemolymph could elicit no significant change in either O₂ affinity or cooperativity of O₂ binding. There was no evidence in support of a specific effect of CO₂ on oxygen affinity of either non-dialysed or dialysed haemolymph.The amount of CO₂ that could be carried byH. transversa haemolymph was significantly reduced by increased temperature (approx. 14 to 12.5 mmol·l^–1 CO₂). Comparisons of oxygenated and deoxygenated haemolymph at a fixed pH were unable to demonstrate the presence of a significant Haldane effect. Combining data from oxygenated and deoxygenated haemolymph the buffer value was calculated to be in the range –6.2 to –8.5 mmol·l^–1 HCO ₃ ^– ·pH unit^–1.The insensitivity ofH. transversa haemocyanin function to all modulating influences except temperature is discussed with respect to the ecology of this crab.     

Developmental consequences of the <Emphasis Type="Italic">tumorous shoot development1</Emphasis> mutation,a novel allele of the cellulose-synthesizing <Emphasis Type="Italic">KORRIGAN1</Emphasis> gene

This work describes the further characterization of the tumorous shoot development1 (tsd1) mutant of Arabidopsis thaliana, which develops disorganized tumorous-like shoot tissue instead of organized leaves and stems. Map-based cloning revealed that tsd1 is a novel strong allele of the KOR1 gene, encoding a membrane-bound endo-1,4-β-d-glucanase involved in cellulose synthesis. To study developmental changes accompanying the aberrant growth of the tsd1 mutant, patterning in the meristems and the hormonal status were analysed by marker genes. Expression of key regulators of meristem maintenance, the CLV3 and STM genes, indicated the presence of numerous meristems in the tsd1 shoot callus. Expression of the LFY::GUS marker supported the ability of the tsd1 callus to form organ primordia, which however failed to develop further. An epidermal marker showed that the L1 layer was maintained only in distinct areas of the tsd1 callus, which could be a reason of disorganized shoot growth. In the tsd1 root meristem, quiescent center activity was lost early after germination, which caused differentiation of the root meristem. The spatial expression of genes reporting the auxin and cytokinin status was altered in the tsd1 mutant. Modifying the endogenous levels of these hormones partially rescued shoot and root development of the tsd1 mutant. Together, the work shows that TSD1/KOR1 is required for maintaining a correct meristematic pattern and organ growth as well as for a normal hormonal response.