Low regeneration efficiency hampers plant transformation. Two independent studies demonstrate that GROWTH-REGULATING FACTORs (GRFs) alone or in chimeras with GRF-INTERACTING FACTOR (GIF) dramatically boost regeneration from tissue cultures from a broad range of species. GRF-GIF chimeras could be a game-changer in plant transformation and gene editing.

GROWTH-REGULATING FACTORs (GRFs) are sequencepecific DNA-binding transcription factors that regulate various aspects of plant growth and development. GRF proteins interact with a transcription cofactor, GRF-INTERACTING FACTOR (GIF), to form a functional transcriptional complex. For its activities, the GRF-GIF duo requires the SWITCH2/ SUCROSE NONFERMENTING2 chromatin remodeling complex. One of the most conspicuous roles of the duo is conferring the meristematic potential on the proliferative and formative cells during organogenesis. GRF expression is post-transcriptionally down-regulated by microRNA396 (miR396), thus constructing the GRF-GIF-miR396 module and fine-tuning the duo's action. Since the last comprehensive review articles were published over three years ago, many studies have added further insight into its action and elucidated new biological roles. The current review highlights recent advances in our understanding of how the GRF-GIF-miR396 module regulates plant growth and development. In addition, I revise the previous view on the evolutionary origin of the GRF gene family. [BMB Reports 2019; 52(4): 227-238].

Soil was incubated with various species of bacteria, Bacillus subtilis, or Bacillus thuringiensis spores and crystals. These were added to serve as potential prey for indigenous, copper-resistant, nonobligate bacterial predators of bacteria in the soil. Alternatively, the soil was incubated with soluble nutrients or water only to cause potential indigenous prey cells to multiply so the predator cells would multiply. All of these incubation procedures caused excessive multiplication of some gram-negative bacteria in soil. Even greater multiplication, however, often occurred for certain copper-resistant bacterial predators of bacteria that made up a part of the gram-negative response. Incubation of the soil with copper per se did not give these responses. In most cases, the copper-resistant bacteria that responded were Cupriavidus necator, bacterial predator L-2, or previously unknown bacteria that resembled them. As was the case for C. necator and L-2, these new bacteria did not use glucose, had white colonies, produced copper-related growth initiation factor (GIF), and attacked B. thuringiensis spores on laboratory media. The results were different, however, when B. thuringiensis spores and crystals per se were added to the soil. The copper-resistant bacterial response in the soil did not, to any extent, include C. necator-like bacteria. Instead, the main copper-resistant bacterial predators that developed had yellow colonies and did not resemble C. necator or L-2 in other ways. They were not seen before, and they did not develop on the addition of B. subtilis spores to soil. Apparently, they could not produce a C. necator-like GIF. Nevertheless, they did respond very quickly to B. thuringiensis spores and crystals in soil, as if a GIF of some sort were involved. These results suggest that, under various conditions of soil incubation, gram-negative bacterial predators of bacteria multiply and that several copper-resistant types among them can be detected, counted, and isolated by plating dilutions of the soil onto media containing excess copper.

GIF, a member of the metallothionein (MT) family (assigned as MT3), is a neuron growth inhibitory factor that inhibits neuron outgrowth in Alzheimer's disease. The conserved Thr5 is one of the main differences between GIF and other members in the MT family. However, natural sheep GIF has an unusual Ala5, casting doubt on the role of common Thr5. We constructed a series of human GIF mutants at site 5, and characterized their biochemical properties by UV spectroscopy, circular dichroism spectroscopy, EDTA reaction, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) reaction, and pH titration. Their inhibitory activity toward neuron survival and neurite extension was also examined. Interestingly, the T5A mutant exhibited distinct metal thiolate activity in the EDTA and DTNB reactions, and also lost its bioactivity. Meanwhile, the T5S mutant had similar biochemical properties and biological activity as wild-type human GIF, indicating the hydroxyl group on the Thr5 was critical to the bioactivity of human GIF. We suggest the hydroxyl group in human GIF may help stabilize the biologically active conformation. On the other hand, lack of the hydroxyl group in sheep GIF may be partially compensated by its abnormal structure.

Despite the advantages of aseptic nonoperative intubation of the small intestine for decompression of obstructed loops, 48% of the attempts lead to failure to pass the tube through the pylorus. The difficulty and inconvenience of passage beyond the stomach have been overcome by the development of a special tube attachment adapted to a fiberoptic duodenoscope (Olympus Model GIF-K). Under direct endoscopic vision the tube can be carried into the second and third portion of the duodenum, released from the scope, and then further prodded into the jejunum. The entire procedure takes less than 15 minutes. Rapid intubation has now been easily carried out in five patients. Three patients had mechanical bowel obstruction. Rapid and effective decompression allowed adequate time for stabilization of concomitant serious problems such as (1) marked cardiopulmonary dysfunction secondary to a near fatal pulmonary embolus, (2) severe peritonitis post appendectomy, and (3) acidosis and dehydration. Surgical correction of the obstructing lesions was safely deferred for up to one week until the concomitant problems improved. The fourth patient, who was a renal transplant recipient, had chronic gastric ileus secondary to duodenal ulcer. Rapid passage of the long tube into the jejunum allowed restoration of nutrition and avoidance of gastrostomy. The fifth patient, with an ileus secondary to an infected abdominal aortic graft, underwent successful decompression but died of sepsis. He represents the only mortality. We propose that jejunal intubation using our technic is not only rapid but relatively easy and should encourage the wider acceptance of aseptic long tube intestinal decompression.

In order to improve the diagnosis of gastric disorders on the basis of biopsy material, we devised larger biopsy forceps (5 mm X 2.5 mm in inside dimensions) which fit into the newer fibergastroscope, GIF-1T (Olympus). Samples from 116 cases yielded 276 specimens; 179 specimens (64.8%) showed the full-thickness of the mucosa with muscularis mucosae, and approximately one-third of the total specimens included a considerable amount of submucosal tissue, but none of them contained parts of muscularis propria. In 4 out of 36 gastric carcinoma cases there was inconsistency between endoscopic and histological recognition of the proximal border of carcinomatous infiltration. Differentiation between adenoma and IIa, and benign and malignant lymphoma were more feasible with our forceps. No complications apart from minor bleeding were seen.

BACKGROUND

Specialized intestinal metaplasia (SIM) in Barrett's esophagus is a risk factor of esophageal adenocarcinoma. It often occurs focally and cannot be distinguished from surrounding columnar epithelium with conventional endoscopy.

OBJECTIVE

The purpose of this study was evaluation of methylene blue (MB) staining and magnification endoscopy with comparison of pit-pattern classifications according to Endo and Guelrud, in detection of SIM in Barrett's esophagus.

METHODS

Twenty-five patients, aged 33-77 years (average 57 years), with displacement of Z line were prospectively enrolled and underwent gastroscopy with the use of magnification up to 115 times (Olympus GIF Q160Z). Biopsy for histopathologic examination was taken from sites stained with MB and/or places with particular pit patterns. A control group consisted of ten patients with normal gastro-esophageal junction.

RESULTS

SIM was proved in nine patients, and significantly more frequently in patients with hiatal hernia and Barrett's segment longer than 3 cm. Round or thin linear pit patterns according to Guelrud's and small round and straight pit patterns according to Endo's classification were coupled with columnar epithelium. SIM was associated with deep linear and foveolar pit patterns in Guelrud's classification. Other pit patterns were less characteristic. Both classifications had high sensitivity (Endo's 85.7%, Guelrud's 92.8%) but poor specificity (respectively, 21.15 and 28.4%) in detection of SIM. Sensitivity and specificity of MB staining were, respectively, 71.4 and 40.6%.

CONCLUSIONS

Despite existing association between mucosal surface structure and histology, we find no convincing data indicating that pit-pattern evaluation may replace multiple biopsies taken according to recommendations from Seattle for detection of SIM in Barrett's esophagus.

Using maximum principles for parabolic and elliptic operators, we examine, in a general way, some models of tissue growth. These typically consist of a model mechanism for the diffusion of a mitotic inhibitor (growth inhibitory factor, GIF) throughout the tissue. Central to the modeling is the inclusion of a source function that models the production of GIF throughout the tissue. We examine the effect this term has on the resulting distribution of GIF in the tissue and comment on the appropriateness of different source functions, in particular a uniform production rate or a nonuniform production rate of inhibitor. Given that it is more appropriate to infer from the patterns of mitosis that are observed experimentally in various tissues the GIF concentration profile rather than the source function profile, it may be more appropriate to use these types of models to determine the qualitative form of the source term rather than proposing this function a priori.

To examine the interindividual differences in the judgment of the visually perceived eye level (VPEL-upright position) and of the visually perceived apparent zenith (VPAZ-supine position) when the subject is subjected to low gravitational-inertial force (GIF), we independently altered GIF in two different populations: control subjects and spatial experts. Subjects were instructed to set a luminous target to the eye level while they were in total darkness and motionless or undergoing low radial acceleration with respect to the threshold of the otolithic system (0.015-1.67 m/sec2 for the VPEL and 0.55-2.19 m/sec2 for the VPAZ, respectively). Results showed that (1) low GIFs, close to those met during daily life, induced an eye level lowering in the upright and supine positions for the control group, and (2) the spatial expertise modified the influence of low GIF. Whereas an oculogravic illusion was found for the control group, this phenomenon was absent (VPAZ) or weaker (VPEL) for the spatial experts. Thus, the relations that the subjects maintain with their spatial environment and the knowledge acquired through experience modify the processing of sensory information and the perceptive construction resulting from it. The interindividual differences in sensitivity to the oculogravic illusion are discussed in terms of sensory dominance and of a better efficiency in the use of the available sensory information.

Juvenile vitamin B(12) or cobalamin (Cbl) deficiency is notoriously difficult to explain due to numerous acquired and inherited causes. The consequences of insufficient Cbl are megaloblastic anemia, nutrient malabsorption, and neurological problems. The treatment is straightforward with parenteral Cbl supplementation that resolves most health issues without an urgent need to clarify their cause. Aside from being clinically unsatisfying, failing to elucidate the basis of Cbl deficiency means important information regarding recurrence risk is not available to the individual if the cause is contagious or inherited. Acquired causes have largely disappeared in the Modern World because they were mostly due to parasites or malnutrition. Today, perhaps the most common causes of juvenile Cbl deficiency are Imerslund-Gräsbeck syndrome and inherited intrinsic factor deficiency (IFD). Three genes are involved and genetic testing is complicated and not widely available. We used self-identified ancestry to accelerate and confirm the genetic diagnosis of IFD in three families of Chaldean origin. A founder mutation limited to Chaldeans from Iraq in the intrinsic factor gene GIF was identified as the cause. World events reshape the genetic structure of populations and inherited diseases in many ways. In this case, all the patients were diagnosed in the USA among recent immigrants from a single region. While IFD itself is not restricted to one kind of people, certain mutations are limited in their range but migrations relocate them along with their host population. As a result, self-identified ancestry as a stratifying characteristic should perhaps be considered in diagnostic strategies for rare genetic disorders.

BACKGROUND

The influence of endoscopic video camera (VC) image quality on surgical performance has not been studied. Flexible endoscopes are used as substitutes for laparoscopes in natural orifice translumenal endoscopic surgery (NOTES), but their optics are originally designed for intralumenal use. Manipulable wired or wireless independent VCs might offer advantages for NOTES but are still under development.

OBJECTIVE

To measure the optical characteristics of 4 VC systems and to compare their impact on the performance of surgical suturing tasks.

METHODS

VC systems included a laparoscope (Storz 10 mm), a flexible endoscope (Olympus GIF 160), and 2 prototype deployable cameras (magnetic anchoring and guidance system [MAGS] Camera and PillCam). In a randomized fashion, the 4 systems were evaluated regarding standardized optical characteristics and surgical manipulations of previously validated ex vivo (fundamentals of laparoscopic surgery model) and in vivo (live porcine Nissen model) tasks; objective metrics (time and errors/precision) and combined surgeon (n = 2) performance were recorded.

RESULTS

Subtle differences were detected for color tests, and field of view was variable (65°-115°). Suitable resolution was detected up to 10 cm for the laparoscope and MAGS camera but only at closer distances for the endoscope and PillCam. Compared with the laparoscope, surgical suturing performances were modestly lower for the MAGS camera and significantly lower for the endoscope (ex vivo) and PillCam (ex vivo and in vivo).

CONCLUSIONS

This study documented distinct differences in VC systems that may be used for NOTES in terms of both optical characteristics and surgical performance. Additional work is warranted to optimize cameras for NOTES. Deployable systems may be especially well suited for this purpose.

Receptors for bioactive glycosylation-inhibiting factor (GIF) were demonstrated using a bioactive mutant of recombinant human (rh) GIF, which is comparable to the suppressor T (Ts) cell-derived bioactive GIF in its affinity for the receptors on helper T (Th) hybridoma cells. Both naive T and B cells in normal mouse spleen lacked GIF receptors. However, presentation of specific antigen to naive T cells resulted in the expression of the receptors on activated T cells. Furthermore, activation of small resting B cells with F(ab')2 fragments of anti-mouse IgM plus IL-4, lipopolysaccharide (LPS) plus IL-4 or LPS plus dextran sulfate induced the expression of the receptors within 48 h of B cell stimulation. It was also found that NK T cells freshly isolated from mouse spleen, but not conventional NK cells, expressed receptors for GIF. CD4(+) and CD4(-) subpopulations of NK T cells showed a similar binding capability. Mature dendritic cells derived from bone marrow did not bear the receptors. The dissociation constant (Kd) of the interaction between the bioactive rhGIF mutant and the high-affinity receptors was 10-100 pM, whereas inactive wild-type rhGIF failed to bind to the receptors. A bioactive derivative of rhGIF suppressed both IgG1 and IgE synthesis by purified B cells activated by LPS and IL-4, indicating that the binding of bioactive GIF to its receptors on activated B cells results in suppression of their differentiation.

This paper is a general appendix to the three parts of 'Celebrating the millennium - historical highlights of photosynthesis research' (Photosynthesis Research, Vols~73(2002), 76(2003), 80(2004)). The major part of this paper includes a comprehensive list of most of the edited volumes on research in the area of photosynthesis. However, I begin this paper by describing selected conferences, related to photosynthesis, held in USA, during 1935-1965, followed by the 1963 International Colloquim held in Gif-sur-Yvette, France (René Wurmser (1890-1993), President); and the 2nd Western European Congress (1965), held in the Netherlands, under the leadership of Jan B. Thomas (1907-1991), both these European conferences being the precursors of the first International Congress on Photosynthesis (1968), organized by Helmut Metzner (1925-1999) at Freudenstadt, Germany. A list of the subsequent international photosynthesis congresses is available in Govindjee and David Krogmann (this issue).

A mathematical model is presented for the production of a growth inhibitory factor (GIF) within a multicell spheroid. The main assumption of the model is that the GIF is produced by cells within the spheroid in some prescribed nonlinear, spatially dependent manner. Given that the diffusion of the GIF is known to take place over a much shorter time scale than that of spheroid growth, the steady-state profile of the GIF in various spheroids of differing radii is examined and theoretical results are compared with actual experimental data.

A method to measure tilt psychophysics in nonhuman primates has been developed and tested. Two rhesus monkeys were trained to orient a light bar parallel to the direction of gravity by rotating a small steering wheel attached to the primate chair. After adequate training, they performed this task during motion paradigms that rotated the gravitoinertial force (GIF) in the roll plane. The animals accurately aligned the light bar with the direction of gravity during and following roll tilts. Subtle aspects of perceived roll tilt previously recorded in human subjects were also observed in the monkeys. During centrifugation and linear translation, an interaural inertial force rotates the GIF in the roll plane. Similar to humans, the animals' perceived direction of gravity shifted toward alignment with the GIF during these paradigms, and the dynamics of these shifts demonstrated an interaction between the otolith afferents that transduce the GIF and rotational cues from the semicircular canals. Finally, optokinetic roll stimulation induced an illusion of roll tilt that was dependent on head orientation, similar to results described in human subjects. Taken together, these findings validate the methodology employed to measure tilt psychophysics; the monkeys' responses were qualitatively similar to those described in human subjects and also recapitulated subtle aspects of the perceptual response observed in humans. This new methodology sets the stage for innovative experimental approaches that will help to elucidate the neural mechanisms underlying the perception of spatial orientation.

BACKGROUND

The purpose of this study was to determine how common sleep-related desaturation with preserved awake resting pulse oximetric saturation (SpO(2)) was in a large cohort of adult cystic fibrosis (CF) patients with variable degrees of pulmonary disease. We then determined whether nocturnal desaturation could reliably be predicted from standard clinical and exercise parameters.

METHODS

Seventy CF patients participated in the study (mean [SD] age, 27.3 [8.7] years; women, 54%; percent predicted FEV(1) [%predFEV(1)], 55.7% [23.9%]). Nocturnal, resting, and exercise SpO(2) were measured. Nocturnal oximetry was measured in the patient's home. Maximal oxygen capacity (Vo(2)max) was determined from a graded exercise test on a stationary bicycle ergometer. The Shwachman-Kulczycki (S-K) illness severity score was calculated incorporating categories of functional capacity, physical examination, nutrition, and chest radiograph.

RESULTS

Multivariate analysis reported significant differences (p < 0.0001) between pulmonary disease severity and overall distribution of nocturnal SpO(2), with the main difference being for patients with severe pulmonary disease (%predFEV(1) of < 50%) compared to patients with mild or moderate disease in the SpO(2) intervals of 100 to 96% (p < 0.0001) and 90 to 86% (p = 0.0001). Pulmonary function, S-K clinical scores, f1.gif" BORDER="0">O(2)max, and resting and maximal SpO(2) correlated significantly (p < 0.05) with nocturnal SpO(2) levels. Stepwise discriminant analysis identified %predFEV(1) (or S-K scores) and resting SpO(2) as the parameters that could best discriminate patients not likely to experience nocturnal desaturation. Specifically, our equation could predict 91% of cases less likely to nocturnally desaturate, but could only modestly predict those more likely to desaturate (i.e., 26% of cases).

CONCLUSIONS

Spirometric parameters and measurements of awake resting oxygenation are of limited utility in predicting nocturnal desaturation. Nocturnal oximetry should be considered in patients with moderate to severe lung disease even with preserved awake resting SpO(2).

All linear accelerometers measure gravito-inertial force, which is the sum of gravitational force (tilt) and inertial force due to linear acceleration (translation). Neural strategies must exist to elicit tilt and translation responses from this ambiguous cue. To investigate these neural processes, we developed a model of human responses and simulated a number of motion paradigms used to investigate this tilt/translation ambiguity. In this model, the separation of GIF into neural estimates of gravity and linear acceleration is accomplished via an internal model made up of 3 principal components: 1) the influence of rotational cues (e.g., semicircular canals) on the neural representation of gravity, 2) the resolution of gravito-inertial force into neural representations of gravity and linear acceleration, and 3) the neural representation of the dynamics of the semicircular canals. By combining these simple hypotheses within the internal model framework, the model mimics human translation and tilt responses for preliminary data from one human subject. These modeled response characteristics are consistent with preliminary data and with the hypothesis that the nervous system uses internal models to estimate tilt and translation in the presence of ambiguous sensory cues.

The balance between trophic factors and inhibitory molecules is likely to determine the outcome of neural tissue damage. The growth inhibitory factor (GIF), a member of the metallothionein family of proteins named metallothionein-III (MT-III), has been suggested to play an important role in tissue repair after adult brain injury. Because no information is available on this factor in relation to immature brain damage, we examined the chronological changes of GIF (MT-III) mRNA and protein following excitotoxic lesions to the postnatal day 9 brain using in situ hybridization and immunocytochemical techniques. We observed a significant decrease of neuronal GIF (MT-III) mRNA and protein levels between 4 and 24 hours postinjury and an increase in glial GIF (MT-III) levels. Double immunocytochemical techniques showed GIF (MT-III) and GFAP positive astrocytes from 2-4 hours postinjury. From 3 days postinjury strongly reactive astrocytes expressed strong levels of both GIF (MT-III) mRNA and protein, which were maintained in the glial scar formed at longer times. These results show the expression of an inhibitory molecule by postnatal reactive astrocytes. Glial GIF (MT-III) expression may play an important role in the tissue reconstruction after immature brain damage.

Orf is an exanthemous viral disease seriously threatening the goat and sheep industry and widely epidemic in the goat and sheep populations in Xinjiang, China. In order to investigate the genetic variability of the orf virus (ORFV), three virus isolates (SHZ1, SHZ2, and SHZ3) were isolated by PCR and Vero cell culture using the clinical samples from the lips of the lambs suspected of ORFV infection. The isolates were further verified by electron microscopy and animal infection experiments. The protective antigen genes B2L, F1L, and virulence genes VIR, GIF, and VEGF in the isolates were cloned, sequenced and analyzed for genetic evolution. The results showed that B2L and F1L were relatively conservative with homology 86.7-97.9%, while VIR, GIF, particularly VEGF were considerably variable with homology 71.5-97.9% at amino acid sequence level, respectively. Phylogenetic tree analysis based on B2L and VIR showed that the isolates SHZ1 and SHZ2 were closely related with the Taiwan isolates. This is the first report to confirm that there have been genetic variations in the Xinjiang ORFV isolates. The findings provide molecular evidence about the genetic variability of the major antigenic and virulence genes in the virus isolates epidemic in Xinjiang.

According to our concept, the development of autoimmune disease depends on the presence of two sets of essential genes, one coding for an abnormal autoreactivity of the immune system, the other for a primary susceptibility of the target organ/structure for the immune attack. The final outcome of the disease in a given individual is then fine tuned by modulatory factors, such as diet or hormones. With regard to the latter, the immuno-endocrine interaction via the hypothalamo-pituitary-adrenal (HPA) axis has proven to be of special importance. Investigating the so-called Obese strain (OS) of chickens, an animal model with a spontaneously occurring Hashimoto-like autoimmune thyroiditis, we have first shown an impaired surge of glucocorticoid hormones after stimulation of the HPA axis by antigens or certain cytokines (glucocorticoid-increasing factors--GIFs). More recently, we have found a similar behavior in models with systemic autoimmune diseases, that is, murine lupus erythematosus and avian scleroderma. More detailed studies have, however, proven that the mechanisms underlying this altered immuno-endocrine communication via the HPA axis differs in different models. Finally, recent data point to the possibility that the classical pathways of glucocorticoid-T-cell interactions also take place in the thymus itself, which has been shown to be a site of steroid hormone production.

Seventy-five endoscopies were performed in 60 patients known to have oesophageal varices presenting with further upper gastrointestinal haemorrhage during the previous 72 hours. A site of active bleeding was found at 50 of 75 examinations (67 percent) including all 21 patients endoscoped within three hours of the last haemorrhage. Variceal bleeding alone was seen in 40 of these 50 examinations (80%) and both varices and mucosal lesions were bleeding in 4 patients; mucosal lesions were an uncommon cause of haemorrhage and only 6 patients were bleeding from these alone. The adult GIF-D2 endoscope was used for 45 examinations. Variceal bleeding was restarted on three occasions and prolonged unconsciousness induced by intravenous diazepam in one patient. In contrast, the paediatric GIF-P endoscope (30 examinations) was easily tolerated with little or no sedation, did not impair diagnostic accuracy and was not associated with any complications.

The objective of the present study was to assess the effectiveness of a combined protocol of muscle stretching and strengthening after immobilization of the hindlimb. Thirty female Wistar rats were divided into 6 groups: group immobilized for 14 days to cause full plantar flexion by cast (GI, n = 6); group immobilized/stretched (GIS, n = 6): submitted to the same immobilization and to 10 days of passive stretching; group immobilized/electrically stimulated (GIES, n = 6): similarly immobilized and submitted to 10 days of low frequency electrical stimulation (ES); group immobilized/stretched/electrically stimulated (GISES, n = 6): similarly immobilized, submitted to 10 days of stretching and ES application; group immobilized/free (GIF, n = 3): similarly immobilized and then left with free limbs for 10 days; control group (CG, n = 3). The middle portion of the soleus muscle was frozen and sections were stained with HE or mATPase. Morphological analysis revealed high cellular reactivity in the GISES, GIES and GIS groups. The lesser diameter and proportion of type I fibers (TIF) and type II fibers (TIIF) (at pH 9.4) and connective area (at HE stain) were measured with an image analyzer and the data obtained were analyzed statistically by the unpaired Student t-test (p < or = 0.05). The results indicated that: a) immobilization generated atrophy of both fiber types (p < 0.05); b) joint application of ES and stretching was not efficient in reestablishing the size of the two fiber types compared to CG (p < 0.05); c) the ES protocol reestablished only the size of TIIF, which showed values similar to those detected in CG (p < 0.05); d) the stretch increased the proliferation of the perimysium connective tissue (p < 0.05). Thus, we conclude that, in the model applied here to female rats, a stretching protocol may limit the volume protein gain of soleus muscle fibers and increase the connective interstitial tissue.

Adaptive radiations are characterized by adaptive diversification intertwined with rapid speciation within a lineage resulting in many ecologically specialized, phenotypically diverse species. It has been proposed that adaptive radiations can originate from ancestral lineages with pronounced phenotypic plasticity in adaptive traits, facilitating ecologically driven phenotypic diversification that is ultimately fixed through genetic assimilation of gene regulatory regions. This study aimed to investigate how phenotypic plasticity is reflected in gene expression patterns in the trophic apparatus of several lineages of East African cichlid fishes, and whether the observed patterns support genetic assimilation. This investigation used a split brood experimental design to compare adaptive plasticity in species from within and outside of adaptive radiations. The plastic response was induced in the crushing pharyngeal jaws through feeding individuals either a hard or soft diet. We find that nonradiating, basal lineages show higher levels of adaptive morphological plasticity than the derived, radiated lineages, suggesting that these differences have become partially genetically fixed during the formation of the adaptive radiations. Two candidate genes that may have undergone genetic assimilation, gif and alas1, were identified, in addition to alterations in the wiring of LPJ patterning networks. Taken together, our results suggest that genetic assimilation may have dampened the inducibility of plasticity related genes during the adaptive radiations of East African cichlids, flattening the reaction norms and canalizing their feeding phenotypes, driving adaptation to progressively more narrow ecological niches.